Tootfinder

On the CQC Conjecture
Hasan Iqbal
https://arxiv.org/abs/2509.08286 https://arxiv.org/pdf/2509.08286

On the CQC Conjecture
The CQC conjecture by Schneeloch et al. (Physical Review A 90.6, 2014) asserts that the sum of classical mutual information between two parties obtained by measuring individual systems in two mutually unbiased bases can not exceed their shared quantum mutual information. This remarkable conjecture, which deserves more work, still remains open. In this article, using a result by Coles and Piani (Physical Review A 89.2, 2014), we derive a sufficient condition for which the CQC conjecture holds. W…

Replaced article(s) found for quant-ph. https://arxiv.org/list/quant-ph/new
[2/2]:
- Enhancing photon-axion conversion probability with squeezed coherent states
Taiki Ikeda, Sugumi Kanno, Jiro Soda

Replaced article(s) found for quant-ph. https://arxiv.org/list/quant-ph/new
[1/2]:
- Heisenberg Scaling Quantum Microscopy: Experiment and Theory
Zhe He, Yide Zhang, Xin Tong, Lei Li, Lihong V. Wang

Correlations and quantum circuits with dynamical causal order
Rapha\"el Mothe, Alastair A. Abbott, Cyril Branciard
https://arxiv.org/abs/2507.07992 ht…

Correlations and quantum circuits with dynamical causal order
Requiring that the causal structure between different parties is well-defined imposes constraints on the correlations they can establish, which define so-called causal correlations. Some of these are known to have a "dynamical" causal order in the sense that their causal structure is not fixed a priori but is instead established on the fly, with for instance the causal order between future parties depending on some choice of action of parties in the past. Here we identify a new way that the cau…

Strong converse rate for asymptotic hypothesis testing in type III
Nicholas Laracuente, Marius Junge
https://arxiv.org/abs/2507.07989 https://

Strong converse rate for asymptotic hypothesis testing in type III
We extend from the hyperfinite setting to general von Neumann algebras Mosonyi and Ogawa's (2015) and Mosonyi and Hiai's (2023) results showing the operational interpretation of sandwiched relative Rényi entropy in the strong converse of hypothesis testing. The specific task is to distinguish between two quantum states given many copies. We use a reduction method of Haagerup, Junge, and Xu (2010) to approximate relative entropy inequalities in an arbitrary von Neumann algebra by those in finit…

Sharp estimates of quantum covering problems via a novel trace inequality
Hao-Chung Cheng, Li Gao, Christoph Hirche, Hao-Wei Huang, Po-Chieh Liu
https://arxiv.org/abs/2507.07961

Sharp estimates of quantum covering problems via a novel trace inequality
In this paper, we prove a novel trace inequality involving two operators. As applications, we sharpen the one-shot achievability bound on the relative entropy error in a wealth of quantum covering-type problems, such as soft covering, privacy amplification, convex splitting, quantum information decoupling, and quantum channel simulation by removing some dimension-dependent factors. Moreover, the established one-shot bounds extend to infinite-dimensional separable Hilbert spaces as well. The pro…

Quantum Wall States for Noise Mitigation and Eternal Purity Bounds
Miguel Casanova, Francesco Ticozzi
https://arxiv.org/abs/2507.07944 https://

Quantum Wall States for Noise Mitigation and Eternal Purity Bounds
The present work analyzes state-stabilization techniques for decoupling a subsystem from environmental interactions. The proposed framework uses analytical and numerical tools to find an approximate decoherence-free subspace (DFS) with enhanced passive noise isolation. Active state-stabilizing control on a subsystem mediating dominant environmental interactions, which we call wall subsystem, creates an effective quantum wall state. The proposed method controls only the wall subsystem, leaving t…

Robust Lindbladian Estimation for Quantum Dynamics
Yinchen Liu, James R. Seddon, Tamara Kohler, Emilio Onorati, Toby S. Cubitt
https://arxiv.org/abs/2507.07912

Robust Lindbladian Estimation for Quantum Dynamics
We revisit the problem of fitting Lindbladian models to the outputs of quantum process tomography. A sequence of prior theoretical works approached the problem by considering whether there exists a Lindbladian generator close to a matrix logarithm of the tomographically estimated transfer matrix. This technique must take into account the non-uniqueness of the matrix logarithm, so that in general multiple branches of the logarithm must be checked. In contrast, all practical demonstrations of Lin…

Testing time order and Leggett-Garg inequalities with noninvasive measurements on public quantum computers
Tomasz Rybotycki, Tomasz Bia{\l}ecki, Josep Batle, Bart{\l}omiej Zglinicki, Adam Szereszewski, Wolfgang Belzig, Adam Bednorz
https://arxiv.org/abs/2507.07904

Testing time order and Leggett-Garg inequalities with noninvasive measurements on public quantum computers
We present two protocols, with one and two two-qubit gates, to noninvasively measure two incompatible observables on a qubit. Both protocols are completed with a projective measurement. By gathering sufficiently large statistics, we have been able to violate Leggett-Garg inequality and time-order invariance. The detailed analysis of the data on 10 qubit sets from 5 devices available on IBM Quantum and one on IonQ reveals violations beyond 5 standard deviations in almost all cases. The noninvasi…

Methods for Reducing Ancilla-Overhead in Block Encodings
Francisca Vasconcelos, Andr\'as Gily\'en
https://arxiv.org/abs/2507.07900 https://

Methods for Reducing Ancilla-Overhead in Block Encodings
Block encodings are a fundamental primitive in quantum algorithms, but can often have large ancilla overhead. In this work, we introduce novel techniques for reducing this overhead in two distinct ways. In Part I, we prove the existence of a "space-time tradeoff" by deriving an algorithm that, for any block encoding, approximately uncomputes all but one of its ancilla (freeing up those ancillae for reuse in later parts of a quantum algorithm). In Part II, we evaluate the minimum number of ancil…

Preparing spin-squeezed states in Rydberg atom arrays via quantum optimal control
Edison S. Carrera, Harold Erbin, Gr\'egoire Misguich
https://arxiv.org/abs/2507.07875

Preparing spin-squeezed states in Rydberg atom arrays via quantum optimal control
We present a quantum optimal control protocol to generate highly spin-squeezed states in Rydberg atom arrays coupled via Ising-type Van der Waals interactions. Using gradient-based optimization techniques we construct time-dependent pulse sequences that steer an initial product state toward highly entangled, spin-squeezed states with predefined magnetization and squeezing axes. We focus on the Wineland parameter $ξ_W^2$ to measure spin squeezing and our approach achieves near-optimal spin sque…

Violation of Bell Inequality with Unentangled Photons
Kai Wang, Zhaohua Hou, Kaiyi Qian, Leizhen Chen, Mario Krenn, Markus Aspelmeyer, Anton Zeilinger, Shining Zhu, Xiao-Song Ma
https://arxiv.org/abs/2507.07756

Violation of Bell Inequality with Unentangled Photons
Violation of local realism via Bell inequality - a profound and counterintuitive manifestation of quantum theory that conflicts with the prediction of local realism - is viewed to be intimately linked with quantum entanglement. Experimental demonstrations of such a phenomenon using quantum entangled states are among the landmark experiments of modern physics and paved the way for quantum technology. Here we report the violation of the Bell inequality that cannot be described by quantum entangle…

Gate Freezing Method for Gradient-Free Variational Quantum Algorithms in Circuit Optimization
Joona Pankkonen, Lauri Ylinen, Matti Raasakka, Andrea Marchesin, Ilkka Tittonen
https://arxiv.org/abs/2507.07742

Gate Freezing Method for Gradient-Free Variational Quantum Algorithms in Circuit Optimization
Parameterized quantum circuits (PQCs) are pivotal components of variational quantum algorithms (VQAs), which represent a promising pathway to quantum advantage in noisy intermediate-scale quantum (NISQ) devices. PQCs enable flexible encoding of quantum information through tunable quantum gates and have been successfully applied across domains such as quantum chemistry, combinatorial optimization, and quantum machine learning. Despite their potential, PQC performance on NISQ hardware is hindered…

Kinetic Inductance Traveling Wave Parametric Amplifiers Near the Quantum Limit: Methodology and Characterization
L. Howe, A. Giachero, M. Vissers, P. Campana, J. Wheeler, J. Gao, J. Austermann, J. Hubmayr, A. Nucciotti, J. Ullom
https://arxiv.org/abs/2507.07706

Kinetic Inductance Traveling Wave Parametric Amplifiers Near the Quantum Limit: Methodology and Characterization
We present a detailed simulation and design framework for realizing traveling wave parametric amplifiers (TWPAs) using the nonlinear kinetic inductance of disordered superconductors -- in our case niobium-titanium-nitride (NbTiN). These kinetic inductance TWPAs (KITs) operate via three-wave mixing (3WM) to achieve high broadband gain and near-quantum-limited (nQL) noise. Representative fabricated devices -- realized using an inverted microstrip (IMS), dispersion-engineered, artificial transmiss…

Strong squeezing and perfect one-way EPR steering in electro-optomechanical system
Qing-Min Zeng, A-Peng Liu, Qi Guo
https://arxiv.org/abs/2507.07697 https…

Strong squeezing and perfect one-way EPR steering in electro-optomechanical system
We consider a three-mode electro-optomechanical system in which a mechanical oscillator is coupled to an optical cavity and a LC circuit through radiation pressure and capacitive coupling, respectively. By controlling the two-tone driving of the optical cavity and the microwave driving of the LC circuit, the strong squeezing of both the microwave field of the LC circuit and the mechanical mode will be obtained. Moreover, by further altering the driving power of the system, the perfect one-way E…

Phase-Space Framework for Noisy Intermediate-Scale Quantum Optical Neural Networks
Stanis{\l}aw \'Swierczewski, Wouter Verstraelen, Piotr Deuar, Barbara Pi\k{e}tka, Timothy C. H. Liew, Micha{\l} Matuszewski, Andrzej Opala
https://arxiv.org/abs/2507.07684

Phase-Space Framework for Noisy Intermediate-Scale Quantum Optical Neural Networks
Quantum optical neural networks (QONNs) enable information processing beyond classical limits by exploiting the advantages of classical and quantum optics. However, simulation of large-scale bosonic lattices remains a significant challenge due to the exponential growth of the Hilbert space required to describe a quantum network accurately. Consequently, previous theoretical studies have been limited to small-scale systems, leaving the behaviour of multimode QONNs largely unexplored. This work p…

Effects of One-particle Reduced Density Matrix Optimization in Variational Quantum Eigensolvers
Amanda Marques de Lima, Erico Souza Teixeira, Eivson Darlivam Rodrigues de Aguiar Silva, Ricardo Luiz Longo
https://arxiv.org/abs/2507.07667

Effects of One-particle Reduced Density Matrix Optimization in Variational Quantum Eigensolvers
The variational quantum eigensolver (VQE) is a promising method for simulating molecular systems on near-term quantum computers. This approach employs energy estimation; however, other relevant molecular properties can be extracted from the one-particle reduced density matrix (1-RDM) generated by VQE. The accuracy of these properties strongly depends on the reliability and convergence of the 1-RDM, which is not guaranteed by energy-only optimization. Thus, we investigate the effect of optimizin…

ProvideQ: A Quantum Optimization Toolbox
Domenik Eichhorn, Nick Poser, Maximilian Schweikart, Ina Schaefer
https://arxiv.org/abs/2507.07649 https://…

ProvideQ: A Quantum Optimization Toolbox
Hybrid solvers for combinatorial optimization problems combine the advantages of classical and quantum computing to overcome difficult computational challenges. Although their theoretical performance seems promising, their practical applicability is challenging due to the lack of a technological stack that can seamlessly integrate quantum solutions with existing classical optimization frameworks. We tackle this challenge by introducing the ProvideQ toolbox, a software tool that enables users to…

Tangent Space Excitation Ansatz for Quantum Circuits
Ji-Yao Chen, Bochen Huang, D. L. Zhou, Norbert Schuch, Chenfeng Cao, Muchun Yang
https://arxiv.org/abs/2507.07646

Tangent Space Excitation Ansatz for Quantum Circuits
Computing the excitation spectra of quantum many-body systems on noisy quantum devices is a promising avenue to demonstrate the practical utility of current quantum processors, especially as we move toward the ``megaquop'' regime. For this task, here we introduce a \textit{tangent-space excitation ansatz} for quantum circuits, motivated by the quasi-particle picture of many-body systems and the structural similarity between quantum circuits and classical tensor networks. Increasing the circuit …

Online Quantum State Tomography via Stochastic Gradient Descent
Jian-Feng Cai, Yuling Jiao, Yinan Li, Xiliang Lu, Jerry Zhijian Yang, Juntao You
https://arxiv.org/abs/2507.07601

Online Quantum State Tomography via Stochastic Gradient Descent
We initiate the study of online quantum state tomography (QST), where the matrix representation of an unknown quantum state is reconstructed by sequentially performing a batch of measurements and updating the state estimate using only the measurement statistics from the current round. Motivated by recent advances in non-convex optimization algorithms for solving low-rank QST, we propose non-convex mini-batch stochastic gradient descent (SGD) algorithms to tackle online QST, which leverage the l…

Quantum Executor: A Unified Interface for Quantum Computing
Giuseppe Bisicchia, Alessandro Bocci, Antonio Brogi
https://arxiv.org/abs/2507.07597 https://…

Quantum Executor: A Unified Interface for Quantum Computing
As quantum computing evolves from theoretical promise to practical deployment, the demand for robust, portable, and scalable tools for quantum software experimentation is growing. This paper introduces Quantum Executor, a backend-agnostic execution engine designed to orchestrate quantum experiments across heterogeneous platforms. Quantum Executor provides a declarative and modular interface that decouples experiment design from backend execution, enabling seamless interoperability and code reus…

CleanQRL: Lightweight Single-file Implementations of Quantum Reinforcement Learning Algorithms
Georg Kruse, Rodrigo Coelho, Andreas Rosskopf, Robert Wille, Jeanette Miriam Lorenz
https://arxiv.org/abs/2507.07593

CleanQRL: Lightweight Single-file Implementations of Quantum Reinforcement Learning Algorithms
At the interception between quantum computing and machine learning, Quantum Reinforcement Learning (QRL) has emerged as a promising research field. Due to its novelty, a standardized and comprehensive collection for QRL algorithms has not yet been established. Researchers rely on numerous software stacks for classical Reinforcement Learning (RL) as well as on various quantum computing frameworks for the implementation of the quantum subroutines of their QRL algorithms. Inspired by the CleanRL l…

A Neural-Guided Variational Quantum Algorithm for Efficient Sign Structure Learning in Hybrid Architectures
Mengzhen Ren, Yu-Cheng Chen, Yangsen Ye, Min-Hsiu Hsieh, Alice Hu, Chang-Yu Hsieh
https://arxiv.org/abs/2507.07555

A Neural-Guided Variational Quantum Algorithm for Efficient Sign Structure Learning in Hybrid Architectures
Variational quantum algorithms hold great promise for unlocking the power of near-term quantum processors, yet high measurement costs, barren plateaus, and challenging optimization landscapes frequently hinder them. Here, we introduce sVQNHE, a neural-guided variational quantum algorithm that decouples amplitude and sign learning across classical and quantum modules, respectively. Our approach employs shallow quantum circuits composed of commuting diagonal gates to efficiently model quantum pha…

Towards Nonlinear Quantum Thermodynamics
Gershon Kurizki, Nilakantha Meher, Avijit Misra, Durga Bhaktavatsala Rao Dasari, Tomas Opatrny
https://arxiv.org/abs/2507.07537

Towards Nonlinear Quantum Thermodynamics
We have recently put forth several schemes of unconventional, nonlinearly-enabled thermodynamic (TD) devices that can operate in either the classical or the quantum domain by transforming thermal-state input in multiple uncorrelated modes into non-gaussian state output in selected modes: a four-mode Kerr-nonlinear interferometer that acts as a heat engine; two coupled Kerr-nonlinear Mach-Zehnder interferometers that act as a phase microscope with unprecedented phase resolution; and a noise sens…

Simulating sparse SYK model with a randomized algorithm on a trapped-ion quantum computer
Etienne Granet, Yuta Kikuchi, Henrik Dreyer, Enrico Rinaldi
https://arxiv.org/abs/2507.07530

Simulating sparse SYK model with a randomized algorithm on a trapped-ion quantum computer
The Sachdev-Ye-Kitaev (SYK) model describes a strongly correlated quantum system that shows a strong signature of quantum chaos. Due to its chaotic nature, the simulation of real-time dynamics becomes quickly intractable by means of classical numerics, and thus, quantum simulation is deemed to be an attractive alternative. Nevertheless, quantum simulations of the SYK model on noisy quantum processors are severely limited by the complexity of its Hamiltonian. In this work, we simulate the real-t…

Conditions for Large-Sample Majorization of Pairs of Flat States in Terms of $\alpha$-$z$ Relative Entropies
Frits Verhagen, Marco Tomamichel, Erkka Haapasalo
https://arxiv.org/abs/2507.07520

Conditions for Large-Sample Majorization of Pairs of Flat States in Terms of $α$-$z$ Relative Entropies
In this work, we offer the first operational interpretation of the $α$-$z$ relative entropies, which were introduced by Jakšić {\it et al.} \cite{Jaksic2012} and Audenaert and Datta \cite{Audenaert_Datta_2015}, where the $α$ and $z$ parameters are truly independent from each other. Namely, we show that these relative entropies appear in the conditions for large-sample or catalytic relative majorization of pairs of flat states and certain generalizations of them. Additionally, the optimal ra…

Exploring the feasibility of probabilistic and deterministic quantum gates between T centers in silicon
Shahrzad Taherizadegan, Faezeh Kimiaee Asadi, Jia-Wei Ji, Daniel Higginbottom, Christoph Simon
https://arxiv.org/abs/2508.06474

Exploring the feasibility of probabilistic and deterministic quantum gates between T centers in silicon
T center defects in silicon provide an attractive platform for quantum technologies due to their unique spin properties and compatibility with mature silicon technologies. We investigate several gate protocols between single T centers, including two probabilistic photon interference-based schemes, a near-deterministic photon scattering gate, and a deterministic magnetic dipole-based scheme. In particular, we study a photon interference-based scheme with feedback which can achieve success probab…

Can a Quantum Computer Simulate Nuclear Magnetic Resonance Spectra Better than a Classical One?
Keith R. Fratus, Nicklas Enenkel, Sebastian Zanker, Jan-Michael Reiner, Michael Marthaler, Peter Schmitteckert
https://arxiv.org/abs/2508.06448

Can a Quantum Computer Simulate Nuclear Magnetic Resonance Spectra Better than a Classical One?
The simulation of the spectra measured in nuclear magnetic resonance (NMR) spectroscopy experiments is a computationally non-trivial problem, and as such, it represents a problem for which a quantum computer may provide some practical advantage over traditional computing methods. In order to understand the extent to which such problems may provide examples of useful quantum advantage, it is important to understand the limitations of existing classical simulation methods. In this work, we benchm…

Nonreciprocal and Geometric Frustration in Dissipative Quantum Spins
Guitao Lyu, Myung-Joong Hwang
https://arxiv.org/abs/2508.06444 https://arxiv.org/pdf/2…

Nonreciprocal and Geometric Frustration in Dissipative Quantum Spins
Nonreciprocal interactions often create conflicting dynamical objectives that cannot be simultaneously satisfied, leading to nonreciprocal frustration. On the other hand, geometric frustration arises when conflicting static objectives in energy minimization cannot be satisfied. In this work, we show that nonreciprocal interaction among three collective quantum spins, mediated by a damped cavity, induces not only nonreciprocal frustration, intrinsic to nonreciprocity, but also geometric frustrat…

Accelerating Quantum Monte Carlo Calculations with Set-Equivariant Architectures and Transfer Learning
Manuel Gallego, Sebasti\'an Roca-Jerat, David Zueco, Jes\'us Carrete
https://arxiv.org/abs/2508.06441

Accelerating Quantum Monte Carlo Calculations with Set-Equivariant Architectures and Transfer Learning
Machine-learning (ML) ansätze have greatly expanded the accuracy and reach of variational quantum Monte Carlo (QMC) calculations, in particular when exploring the manifold quantum phenomena exhibited by spin systems. However, the scalability of QMC is still compromised by several other bottlenecks, and specifically those related to the actual evaluation of observables based on random deviates that lies at the core of the approach. Here we show how the set-transformer architecture can be used t…

Nonparametric Learning Non-Gaussian Quantum States of Continuous Variable Systems
Liubov A. Markovich, Xiaoyu Liu, Jordi Tura
https://arxiv.org/abs/2508.06431 https://

Nonparametric Learning Non-Gaussian Quantum States of Continuous Variable Systems
Continuous-variable quantum systems are foundational to quantum computation, communication, and sensing. While traditional representations using wave functions or density matrices are often impractical, the tomographic picture of quantum mechanics provides an accessible alternative by associating quantum states with classical probability distribution functions called tomograms. Despite its advantages, including compatibility with classical statistical methods, tomographic method remain underuti…

Single photon emission from lithographically-positioned engineered nanodiamonds for cryogenic applications
Vivekanand Tiwari, Zhaojin Liu, Hao-Cheng Weng, Krishna C Balram, John G Rarity, Soumen Mandal, Oliver A Williams, Gavin W Morley, Joe A Smith
https://arxiv.org/abs/2508.06424

Single photon emission from lithographically-positioned engineered nanodiamonds for cryogenic applications
Nitrogen-vacancy centres in nanodiamonds (NDs) provide a promising resource for quantum photonic systems. However, developing a technology beyond proof-of-principle physics requires optimally engineering its component parts. In this work, we present a hybrid materials platform by photolithographically positioning ball-milled isotopically-enriched NDs on broadband metal reflectors. The structure enhances the photonic collection efficiency, enabling cryogenic characterisation despite the limited …

Quantum Annealing for the Set Splitting Problem
Sean Borneman
https://arxiv.org/abs/2508.06410 https://arxiv.org/pdf/2508.06410

Quantum Annealing for the Set Splitting Problem
I present a novel use of quantum annealing to solve the Set Splitting Problem using (QUBO) problem formulation. The contribution of the work is in formulating penalty functions that ensure the ground state of the QUBO Hamiltonian corresponds to valid solutions that split the input subsets. This approach scales linearly in terms of the number of logical qubits relative to problem size. Empirical tests of the proposed solution show convergence to globally optimal solutions, with high accuracy rat…

Quasi-stationary normal states for quantum Markov semigroups
Ameur Dhahri, Franco Fagnola, Federico Girotti, Hyun Jae Yoo
https://arxiv.org/abs/2508.06396 https://

Quasi-stationary normal states for quantum Markov semigroups
We introduce the notion of Quasi-Stationary State (QSS) in the context of quantum Markov semigroups that generalizes the one of quasi-stationary distribution in the case of classical Markov chains. We provide an operational interpretation of QSSs using the theory of direct and indirect quantum measurements. Moreover, we prove that there is a connection between QSSs and spectral properties of the quantum Markov semigroup. Finally, we discuss some examples which, despite their simplicity, already…

Design and analysis of a set of discrete variable protocols for secure quantum communication
Arindam Dutta
https://arxiv.org/abs/2508.06380 https://arxiv.o…

Design and analysis of a set of discrete variable protocols for secure quantum communication
The advent of quantum key distribution (QKD) has revolutionized secure communication by providing unconditional security, unlike classical cryptographic methods. However, its effectiveness relies on robust identity authentication, as vulnerabilities in the authentication process can cause a compromise with the security of the entire communication system. Over the past three decades, numerous quantum identity authentication (QIA) protocols have been proposed. This thesis first presents a chronol…

SQUID G.A.M.E.: Gamma, Atmospheric, and Mono-Energetic Neutron Effects on Quantum Devices
Gioele Casagranda, Elizabeth Auden, Carlo Cazzaniga, Maria Kastriotou, Christopher Frost, Marzio Vallero, Flavio Vella, Paolo Rech
https://arxiv.org/abs/2508.06362

SQUID G.A.M.E.: Gamma, Atmospheric, and Mono-Energetic Neutron Effects on Quantum Devices
Quantum devices are a promising solution to many research applications, including medical imaging, precision magnetic field measurements, condensed matter physics, and overcoming the limits of classical computing. Among the available implementations, the superconducting technology is the current focus of scientific research and industrial applications, excelling in performance and scalability. Despite this, superconducting quantum systems are extremely prone to decoherence, and in particular, t…

The Dual Role of Low-Weight Pauli Propagation: A Flawed Simulator but a Powerful Initializer for Variational Quantum Algorithms
Zong-Liang Li, Shi-Xin Zhang
https://arxiv.org/abs/2508.06358

The Dual Role of Low-Weight Pauli Propagation: A Flawed Simulator but a Powerful Initializer for Variational Quantum Algorithms
Variational quantum algorithms (VQAs) rely on a classical optimizer to tune a parameterized quantum circuit, raising the question of whether classical methods can assist in this process. In this work, we investigate the low-weight Pauli propagation (LWPP) algorithm as a potential classical tool for simulating the VQA circuit. We first find that LWPP is an unreliable estimator of the true energy, limiting its utility as a direct simulator. However, we uncover its real value: despite this numeric…

Quantum Algorithm for Estimating Intrinsic Geometry
Nhat A. Nghiem, Tuan K. Do, Tzu-Chieh Wei, Trung V. Phan
https://arxiv.org/abs/2508.06355 https://arxiv…

Quantum Algorithm for Estimating Intrinsic Geometry
High-dimensional datasets typically cluster around lower-dimensional manifolds but are also often marred by severe noise, obscuring the intrinsic geometry essential for downstream learning tasks. We present a quantum algorithm for estimating the intrinsic geometry of a point cloud -- specifically its local intrinsic dimension and local scalar curvature. These quantities are crucial for dimensionality reduction, feature extraction, and anomaly detection -- tasks that are central to a wide range …

Arbitrarily-high-dimensional reconciliation via cross-rotation for continuous-variable quantum key distribution
Jisheng Dai, Xue-Qin Jiang, Tao Wang, Peng Huang, Guihua Zeng
https://arxiv.org/abs/2508.06338

Arbitrarily-high-dimensional reconciliation via cross-rotation for continuous-variable quantum key distribution
Multidimensional rotation serves as a powerful tool for enhancing information reconciliation and extending the transmission distance in continuous-variable quantum key distribution (CV-QKD). However, the lack of closed-form orthogonal transformations for high-dimensional rotations has limited the maximum reconciliation efficiency to channels with 8 dimensions over the past decade. This paper presents a cross-rotation scheme to overcome this limitation and enable reconciliation in arbitrarily hi…

Shortcuts to adiabaticity with a quantum control field
Emma C. King, Giovanna Morigi, Rapha\"el Menu
https://arxiv.org/abs/2508.06304 https://arxiv.or…

Shortcuts to adiabaticity with a quantum control field
Quantum adiabatic dynamics is the crucial element of adiabatic quantum computing and quantum annealing. Shortcuts to adiabaticity enable acceleration of the computational time by suppressing unwanted non-adiabatic processes with designed classical fields. Here, we consider quantum state transfer in the Landau-Zener model, which exemplifies the key elements of quantum adiabatic dynamics. We argue that non-adiabatic transitions can be suppressed by autonomous quantum dynamics, which involves coup…

Secure Hybrid Key Growing via Coherence Witnessing and Bipartite Encoding
Pol Juli\`a Farr\'e, Chris Aaron Schneider, Christian Deppe
https://arxiv.org/abs/2508.06294 https:…

Secure Hybrid Key Growing via Coherence Witnessing and Bipartite Encoding
We propose a novel Hybrid Key Growing (HKG) protocol based on quantum principles and a classical physical-layer assumption. We simultaneously exploit the quantum photon-number and photon-time-bin Degrees of Freedom (DoFs), effectively doubling the bit-per-pulse rate compared to conventional Quantum Key Growing (QKG) schemes. Our protocol integrates entity authentication, and is designed for practical implementation by avoiding reliance on single-photon sources or detectors. By incorporating pri…

Cavity-based optical switching via phase modulation in warm rubidium vapor
Georgia Booton, Tabijah Wasawo, William O. C. Davis, Cameron McGarry, K. R. Rusimova, Alex O. C. Davis, Josh Nunn, Peter J. Mosley
https://arxiv.org/abs/2508.06255

Cavity-based optical switching via phase modulation in warm rubidium vapor
Optical switching remains a key outstanding challenge for scalable fault-tolerant photonic quantum computing due to the trade-off between speed, bandwidth, and loss. Scalable quantum photonics demands all three, to enable high computational clock rates and resource efficient scaling to large systems. We present a cavity-based optical switch that overcomes this limitation, demonstrating 22 ns rise time, insertion loss of 2.4 dB, and 17.5 dB extinction ratio. All-optical control is achieved via p…

Supercoherence: Harnessing Long-Range Interactions to Preserve Collective Coherence in Disordered Systems
Alexey Gorlach, Andrea Pizzi, Klaus M{\o}lmer, Joseph Avron, Mordechai Segev, Ido Kaminer
https://arxiv.org/abs/2508.06238

Supercoherence: Harnessing Long-Range Interactions to Preserve Collective Coherence in Disordered Systems
Artificial quantum systems with synthetic dimensions enable exploring novel quantum phenomena difficult to create in conventional materials. These synthetic degrees of freedom increase the system's dimensionality without altering its physical structure, accessing higher-dimensional physics in lower-dimensional setups. However, synthetic quantum systems often suffer from intrinsic disorder, causing rapid decoherence that limits scalability, a major obstacle in quantum information science. Here, …

Space and Time Cost of Continuous Rotations in Surface Codes
Zhu Sun, Balint Koczor
https://arxiv.org/abs/2508.06236 https://arxiv.org/pdf/2508.06236

Space and Time Cost of Continuous Rotations in Surface Codes
While Clifford operations are relatively easy to implement in fault-tolerant quantum computers,continuous rotation gates remain a significant bottleneck in typical quantum algorithms. In this work, we ask the question: "What is the most efficient approach for implementing continuous rotations in a surface code architecture?" Several techniques have been developed to reduce the T-count or T-depth of rotations, such as Hamming weight phasing and catalyst towers. However, these methods often requi…

Aspheric lens design proposal for near-perfect mode-matching of a broadband quantum dot micropillar to a single-mode fibre
Yichen Zhang, David Dlaka, James McDougall, James Y Tai, Petros Androvitsaneas, Edmund Harbord, Ruth Oulton, Andrew B. Young
https://arxiv.org/abs/2508.06223

Aspheric lens design proposal for near-perfect mode-matching of a broadband quantum dot micropillar to a single-mode fibre
Quantum dots in micropillars are one of the most promising options for a bright, deterministic single photon source. While highly efficient devices (>95%) have been designed, there remains a significant bottleneck that impacts the overall system efficiency: the large numerical aperture of the output mode. This leads to inefficient coupling of emitted photons into single-mode fibre, thus limiting practical integration into quantum computing and communication architectures. We show that with the …

Detecting entanglement between quantum emitters using directional emission
Ivan Saychenko, Robert Weiss, Rita Veilande, Scott Parkins, Mark Sadgrove, Sandro Wimberger
https://arxiv.org/abs/2508.06210

Detecting entanglement between quantum emitters using directional emission
Recently, it was shown that quantum interference in a system containing a polarized and unpolarized emitter can allow directional emission of photons into a circulating cavity. Here, we ask whether high directionality of photon emission in this system implies a high degree of quantum correlation between the two emitters. We show that the answer is a qualified "yes", with photon emission directionality and emitter-emitter entanglement showing a monotonic relationship over a broad parameter range…

The loss tolerance of cat breeding for fault-tolerant grid state generation
Olga Solodovnikova, Ulrik L. Andersen, Jonas S. Neergaard-Nielsen
https://arxiv.org/abs/2508.06193 ht…

The loss tolerance of cat breeding for fault-tolerant grid state generation
The development of a continuous-variable photonic quantum computer depends on the reliable preparation of high-quality Gottesman-Kitaev-Preskill states. The most promising GKP preparation scheme is the cat breeding protocol, which can generate GKP states deterministically given a source of squeezed cat states, using beam splitters, homodyne detectors and a feedforward displacement. However, analyzing the performance of the protocol under loss is cumbersome due to the exponential scaling of the …

Scalable Quantum State Preparation for Encoding Genomic Data with Matrix Product States
Floyd M. Creevey, Hitham T. Hassan, James McCafferty, Lloyd C. L. Hollenberg, Sergii Strelchuk
https://arxiv.org/abs/2508.06184

Scalable Quantum State Preparation for Encoding Genomic Data with Matrix Product States
As quantum computing hardware advances, the need for algorithms that facilitate the loading of classical data into the quantum states of these devices has become increasingly important. This study presents a method for producing scalable quantum circuits to encode genomic data using the Matrix Product State (MPS) formalism. The method is illustrated by encoding the genome of the bacteriophage $ΦX174$ into a 15-qubit state, and analysing the trade-offs between MPS bond dimension, reconstruction…

Fast simulations of continuous-variable circuits using the coherent state decomposition
Olga Solodovnikova, Ulrik L. Andersen, Jonas S. Neergaard-Nielsen
https://arxiv.org/abs/2508.06175

Fast simulations of continuous-variable circuits using the coherent state decomposition
We present \texttt{lcg\_plus}, an open-source Python library for the simulation of continuous-variable quantum circuits with both generaldyne and photon-number-resolving detector capabilities. Our framework merges the linear combination of Gaussians methodology with the coherent state decomposition of arbitrary non-Gaussian states, forming a bridge between the Gaussian and Fock basis representations. By tracking the Wigner function, we can simulate the action of Gaussian channels and measuremen…

Diagonalizing large-scale quantum many-body Hamiltonians using variational quantum circuit and tensor network
Peng-Fei Zhou, Shuang Qiao, An-Chun Ji, Shi-Ju Ran
https://arxiv.org/abs/2508.06159

Diagonalizing large-scale quantum many-body Hamiltonians using variational quantum circuit and tensor network
Exact diagonalization (ED) is an essential tool for exploring quantum many-body physics but is fundamentally limited by the exponentially-scaled computational complexity. Here, we propose tensor network variational diagonalization (TNVD), which encodes the full eigenenergy spectrum of a quantum many-body Hamiltonian into a matrix product state, and encodes the eigenstates as the evolutions of product states using variational quantum circuit (VQC). Thereby, TNVD reduces the computational complex…

Enhancing the Scalability of Classical Surrogates for Real-World Quantum Machine Learning Applications
Philip Anton Hernicht, Alona Sakhnenko, Corey O'Meara, Giorgio Cortiana, Jeanette Miriam Lorenz
https://arxiv.org/abs/2508.06131

Enhancing the Scalability of Classical Surrogates for Real-World Quantum Machine Learning Applications
Quantum machine learning (QML) presents potential for early industrial adoption, yet limited access to quantum hardware remains a significant bottleneck for deployment of QML solutions. This work explores the use of classical surrogates to bypass this restriction, which is a technique that allows to build a lightweight classical representation of a (trained) quantum model, enabling to perform inference on entirely classical devices. We reveal prohibiting high computational demand associated wit…

Quantum Optimization on Rydberg Atom Arrays with Arbitrary Connectivity: Gadgets Limitations and a Heuristic Approach
Pierre Cazals, Amalia Sorondo, Victor Onofre, Constantin Dalyac, Wesley da Silva Coelho, Vittorio Vitale
https://arxiv.org/abs/2508.06130

Quantum Optimization on Rydberg Atom Arrays with Arbitrary Connectivity: Gadgets Limitations and a Heuristic Approach
Programmable quantum systems based on Rydberg atom arrays have recently emerged as a promising testbed for combinatorial optimization. Indeed, the Maximum Weighted Independent Set problem on unit-disk graphs can be efficiently mapped to such systems due to their geometric constraints. However, extending this capability to arbitrary graph instances typically necessitates the use of reduction gadgets, which introduce additional experimental overhead and complexity. Here, we analyze the complexity…

Near-Heisenberg-limited parallel amplitude estimation with logarithmic depth circuit
Kohei Oshio, Kaito Wada, Naoki Yamamoto
https://arxiv.org/abs/2508.06121 https://

Near-Heisenberg-limited parallel amplitude estimation with logarithmic depth circuit
Quantum amplitude estimation is one of the core subroutines in quantum algorithms. This paper gives a parallelized amplitude estimation (PAE) algorithm, that simultaneously achieves near-Heisenberg scaling in the total number of queries and sub-linear scaling in the circuit depth, with respect to the estimation precision. The algorithm is composed of a global GHZ state followed by separated low-depth Grover circuits; the number of qubits in the GHZ state and the depth of each circuit is tunable…

Federated Quantum Kernel-Based Long Short-term Memory for Human Activity Recognition
Yu-Chao Hsu, Jiun-Cheng Jiang, Chun-Hua Lin, Wei-Ting Chen, Kuo-Chung Peng, Prayag Tiwari, Samuel Yen-Chi Chen, En-Jui Kuo
https://arxiv.org/abs/2508.06078

Federated Quantum Kernel-Based Long Short-term Memory for Human Activity Recognition
In this work, we introduce the Federated Quantum Kernel-Based Long Short-term Memory (Fed-QK-LSTM) framework, integrating the quantum kernel methods and Long Short-term Memory into federated learning.Within Fed-QK-LSTM framework, we enhance human activity recognition (HAR) in privacy-sensitive environments and leverage quantum computing for distributed learning systems.The DeepConv-QK-LSTM architecture on each client node employs convolutional layers for efficient local pattern capture, this de…

State-adaptive quantum error correction and fault-tolerant quantum computing
D. -S. Wang
https://arxiv.org/abs/2508.06011 https://arxiv.org/pdf/2508.06011

State-adaptive quantum error correction and fault-tolerant quantum computing
We present a theoretical framework for state-adaptive quantum error correction (SAQEC) that bridges the gap between quantum computing and error correction paradigms. By incorporating knowledge of quantum states into the error correction process, we establish a new capacity regime governed by quantum mutual information rather than coherent information. This approach reveals a fundamental connection to entanglement-assisted protocols. We demonstrate practical applications in fault-tolerant quantu…

A spin-embedded diamond optomechanical resonator with mechanical quality factor exceeding one million
Hyunseok Oh, Viraj Dharod, Carl Padgett, Lillian B. Hughes, Jayameenakshi Venkatraman, Shreyas Parthasarathy, Ekaterina Osipova, Ian Hedgepeth, Jeffrey V. Cady, Luca Basso, Yongqiang Wang, Michael Titze, Edward S. Bielejec, Andrew M. Mounce, Dirk Bouwmeester, Ania C. Bleszynski Jayich

A spin-embedded diamond optomechanical resonator with mechanical quality factor exceeding one million
Diamond optomechanical crystal (OMC) devices with embedded color center spins are promising platforms for a broad range of applications in quantum sensing, networking, and computing applications, offering an interface between a GHz-frequency mechanical mode and both optical photons and coherent spins. A crucial but elusive step towards realizing this platform is to engineer a device with a high-quality factor mechanical mode while preserving the bulk-like coherence of embedded spins. Here we de…

MPS-JuliQAOA: User-friendly, Scalable MPS-based Simulation for Quantum Optimization
Sean Feeney, Reuben Tate, John Golden, Stephan Eidenbenz
https://arxiv.org/abs/2508.05883 htt…

MPS-JuliQAOA: User-friendly, Scalable MPS-based Simulation for Quantum Optimization
We present the MPS-JuliQAOA simulator, a user-friendly, open-source tool to simulate the Quantum Approximate Optimization Algorithm (QAOA) of any optimization problem that can be expressed as diagonal Hamiltonian. By leveraging Julia-language constructs and the ITensor package to implement a Matrix Product State (MPS) approach to simulating QAOA, MPS-Juli-QAOA effortlessly scales to 512 qubits and 20 simulation rounds on the standard de-facto benchmark 3-regular MaxCut QAOA problem. MPS-JuliQAO…

Tailored First-order and Interior-point methods and a new semidefinite programming hierarchy for entanglement detection
Javier Pena, Vikesh Siddhu, Sridhar Tayur
https://arxiv.org/abs/2508.05854

Tailored First-order and Interior-point methods and a new semidefinite programming hierarchy for entanglement detection
Quantum entanglement lies at the heart of quantum information science, yet its reliable detection in high-dimensional or noisy systems remains a fundamental computational challenge. Semidefinite programming (SDP) hierarchies, such as the Doherty-Parrilo-Spedalieri (DPS) and Extension (EXT) hierarchies, offer complete methods for entanglement detection, but their practical use is limited by exponential growth in problem size. In this paper, we introduce a new SDP hierarchy, PST, that is sandwich…

Riemann-Zeta-Regularisation of Feynman Path Integrals
Cyril Belardinelli
https://arxiv.org/abs/2508.05815 https://arxiv.org/pdf/2508.05815

Riemann-Zeta-Regularisation of Feynman Path Integrals
The Feynman Propagator of a charged particle confined to an anisotropic Harmonic Oscillator potential and moving in a crossed electromagnetic field is calculated in a conceptually new way. The calculation is based on the expansion of the path variable into a complex Fourier series. The path integral then becomes an infinite product of Gaussian integrals. This product is divergent. It turns out that we can regularize this product by using the zeta-function. It is a remarkable fact that the zeta-…

Modular Quantum Amplitude Estimation: A Scalable and Adaptive Framework
Alok Shukla, Prakash Vedula
https://arxiv.org/abs/2508.05805 https://arxiv.org/pdf/…

Modular Quantum Amplitude Estimation: A Scalable and Adaptive Framework
Quantum Amplitude Estimation (QAE) is a key primitive in quantum computing, but its standard implementation using Quantum Phase Estimation is resource-intensive, requiring a large number of coherent qubits in a single circuit block to achieve high precision. This presents a significant challenge for near-term Noisy Intermediate-Scale Quantum (NISQ) devices. To address this, we introduce the Adaptive Windowed Quantum Amplitude Estimation (AWQAE) framework, a modular, scalable and adaptive approa…

Benchmarking quantum computers with any quantum algorithm
Stefan K. Seritan, Aditya Dhumuntarao, Aidan Q. Wilber-Gauthier, Kenneth M. Rudinger, Antonio E. Russo, Robin Blume-Kohout, Andrew D. Baczewski, Timothy Proctor
https://arxiv.org/abs/2508.05754

Benchmarking quantum computers with any quantum algorithm
Application-based benchmarks are increasingly used to quantify and compare quantum computers' performance. However, because contemporary quantum computers cannot run utility-scale computations, these benchmarks currently test this hardware's performance on ``small'' problem instances that are not necessarily representative of utility-scale problems. Furthermore, these benchmarks often employ methods that are unscalable, limiting their ability to track progress towards utility-scale applications…

Generalized Holstein-Primakoff mapping and $1/N$ expansion of collective spin systems undergoing single particle dissipation
Diego Barberena
https://arxiv.org/abs/2508.05751 htt…

Generalized Holstein-Primakoff mapping and $1/N$ expansion of collective spin systems undergoing single particle dissipation
We develop a generalization of the Schwinger boson and Holstein-Primakoff transformations that is applicable to ensembles of $N$ spin $1/2$'s with weak permutational symmetry. These generalized mappings are constructed by introducing two independent bosonic variables that describe fluctuations parallel and transverse to the collective Bloch vector built out of the original spin $1/2$'s. Using this representation, we develop a systematic $1/N$ expansion and write down explicitly leading and next…

Expressivity Limits and Trainability Guarantees in Quantum Walk-based Optimization
Guilherme A. Bridi, Debbie Lim, Lirand\"e Pira, Raqueline A. M. Santos, Franklin de L. Marquezino, Soumik Adhikary
https://arxiv.org/abs/2508.05749

Expressivity Limits and Trainability Guarantees in Quantum Walk-based Optimization
Quantum algorithms have emerged as a promising tool to solve combinatorial optimization problems. The quantum walk optimization algorithm (QWOA) is one such variational approach that has recently gained attention. In the broader context of variational quantum algorithms (VQAs), understanding the expressivity and trainability of the ansatz has proven critical for evaluating their performance. A key method to study both these aspects involves analyzing the dimension of the dynamic Lie algebra (DL…

Classical simulation of noisy quantum circuits via locally entanglement-optimal unravelings
Simon Cichy, Paul K. Faehrmann, Lennart Bittel, Jens Eisert, Hakop Pashayan
https://arxiv.org/abs/2508.05745 …

Classical simulation of noisy quantum circuits via locally entanglement-optimal unravelings
Classical simulations of noisy quantum circuits is instrumental to our understanding of the behavior of real world quantum systems and the identification of regimes where one expects quantum advantage. In this work, we present a highly parallelizable tensor-network-based classical algorithm -- equipped with rigorous accuracy guarantees -- for simulating $n$-qubit quantum circuits with arbitrary single-qubit noise. Our algorithm represents the state of a noisy quantum system by a particular ense…

A quantum computing approach to efficiently simulating correlated materials using impurity models and dynamical mean field theory
Norman Hogan, Efekan K\"okc\"u, Thomas Steckmann, Liam P. Doak, Carlos Mejuto-Zaera, Daan Camps, Roel Van Beeumen, Wibe A. de Jong, A. F. Kemper
https://arxiv.org/abs/2508.05738

A quantum computing approach to efficiently simulating correlated materials using impurity models and dynamical mean field theory
The accurate theoretical description of materials with strongly correlated electrons is a formidable challenge, at the forefront of condensed matter physics and computational chemistry alike, and it is one of the targets for quantum computing. Dynamical Mean Field Theory (DMFT) is a successful approach that predicts behaviors of such systems by incorporating some correlated behavior, but it is limited by the need to calculate the Green's function for the impurity model. This work proposes a fra…

Role of Plaquette Term in Genuine $2 1$D String Dynamics on Quantum Simulators
Yizhuo Tian, N. S. Srivatsa, Kaidi Xu, Jesse J. Osborne, Umberto Borla, Jad C. Halimeh
https://arxiv.org/abs/2508.05736

Role of Plaquette Term in Genuine $2+1$D String Dynamics on Quantum Simulators
With the advent of quantum simulators of $2+1$D lattice gauge theories (LGTs), a fundamental open question is under what circumstances the observed physics is genuinely $2+1$D rather than effectively $1+1$D. Here, we address this question in the ongoing strong effort to quantum-simulate string dynamics in $2+1$D LGTs on state-of-the-art quantum hardware. Through tensor network simulations and analytic derivations, we show that the plaquette term, which represents a magnetic field and only emerg…

Replaced article(s) found for quant-ph. https://arxiv.org/list/quant-ph/new
[2/2]:
- Quon Classical Simulation: Unifying Cliffords, Matchgates and Entanglement
Zixuan Feng, Zhengwei Liu, Fan Lu, Ningfeng Wang

Replaced article(s) found for quant-ph. https://arxiv.org/list/quant-ph/new
[1/2]:
- Gaining confidence on the correct realization of arbitrary quantum computations
Jose Carrasco, Marc Langer, Antoine Neven, Barbara Kraus

$\bf A^2$-robust superradiant phase transition in hybrid qubit-cavity optomechanics
Gang Liu, Wei Xiong
https://arxiv.org/abs/2508.08024 https://arxiv.org/…

$\bf A^2$-robust superradiant phase transition in hybrid qubit-cavity optomechanics
The $\mathbf{A}^2$ term presents a fundamental challenge to realizing the superradiant phase transition (SPT) in cavity quantum electrodynamics. Here, we propose a hybrid quantum system enabling SPT regardless of the presence of the $\mathbf{A}^2$ term. The system consisting of a qubit, a mechanical mode, and an optical cavity, where the qubit and mechanical mode constitute a quantum Rabi model, while the mechanical mode and cavity form an optomechanical system. Crucially, the auxiliary cavity …

Expanding a 4-qubit Dicke State a to 5-qubit Dicke State with Limited Qubit Access
Bibhuti Thapa, Oberon Moran, Duc-Kha Vu, Fatih Ozaydin
https://arxiv.org/abs/2508.07977 https:…

Expanding a 4-qubit Dicke State a to 5-qubit Dicke State with Limited Qubit Access
In scenarios where full access to all qubits of a multipartite quantum system is available and global operations can be implemented, the preparation of arbitrary entangled states - including multipartite Dicke states - is theoretically straightforward. However, practical constraints often limit direct control over all qubits. In this work, we first present an efficient method for preparing a four-qubit Dicke state, and then demonstrate how a four-qubit Dicke state can be expanded to a five-qubi…

Calculating the Projective Norm of higher-order tensors using a gradient descent algorithm
Aaditya Rudra, Maria Anastasia Jivulescu
https://arxiv.org/abs/2508.07933 https://

Calculating the Projective Norm of higher-order tensors using a gradient descent algorithm
Projective Norms are a class of tensor norms that map on the input and output spaces. These norms are useful for providing a measure of entanglement. Calculating the projective norms is an NP-hard problem, which creates challenges in computing due to the complexity of the exponentially growing parameter space for higher-order tensors. We develop a novel gradient descent algorithm to estimate the projective norm of higher-order tensors. The algorithm guarantees convergence to a minimum nuclear r…

Scheduling of syndrome measurements with a few ancillary qubits
Shintaro Sato, Yasunari Suzuki
https://arxiv.org/abs/2508.07913 https://arxiv.org/pdf/2508.…

Scheduling of syndrome measurements with a few ancillary qubits
Quantum error-correcting codes are a vital technology for demonstrating reliable quantum computation. They require data qubits for encoding quantum information and ancillary qubits for taking error syndromes necessary for error correction. The need for a large number of ancillary qubits is an overhead specific to quantum computing, and it prevents the scaling of quantum computers to a useful size. In this work, we propose a framework for generating efficient syndrome measurement circuits with a…

GPU-Accelerated Syndrome Decoding for Quantum LDPC Codes below the 63 $\mu$s Latency Threshold
Oscar Ferraz, Bruno Coutinho, Gabriel Falcao, Marco Gomes, Francisco A. Monteiro, Vitor Silva
https://arxiv.org/abs/2508.07879

GPU-Accelerated Syndrome Decoding for Quantum LDPC Codes below the 63 $μ$s Latency Threshold
This paper presents a GPU-accelerated decoder for quantum low-density parity-check (QLDPC) codes that achieves sub-$63$ $μ$s latency, below the surface code decoder's real-time threshold demonstrated on Google's Willow quantum processor. While surface codes have demonstrated below-threshold performance, the encoding rates approach zero as code distances increase, posing challenges for scalability. Recently proposed QLDPC codes, such as those by Panteleev and Kalachev, offer constant-rate encod…

Information Transport in Classic-Quantum Hybrid System
Julian Rapp, Radhika H. Joshi, Alwin van Steensel, Yuli V. Nazarov, Mohammad H. Ansari
https://arxiv.org/abs/2508.07870 ht…

Information Transport in Classic-Quantum Hybrid System
Many important quantities in quantum information science, such as entropy and entanglement, are non-linear functions of the density matrix and cannot be expressed as operator observables. Standard open-system approaches evolve only a single copy of the density matrix, making it impossible to track the dynamics of such quantities. A formalism proposed by some of the present authors addressed this challenge by evolving multiple virtual replicas, but was limited to the weak-coupling regime. Here, …

Master Equation for Quantum Self-Organization of Atoms and Molecules in Cavities
Tom Schmit, Catalin-Mihai Halati, Tobias Donner, Giovanna Morigi, Simon B. J\"ager
https://arxiv.org/abs/2508.07853

Master Equation for Quantum Self-Organization of Atoms and Molecules in Cavities
Quantum gases of atoms and molecules in optical cavities offer a formidable laboratory for studying the out-of-equilibrium dynamics of long-range interacting systems. Multiple scattering of cavity photons mediate interactions, and the emerging phases of matter are determined by the interplay of photon-mediated forces, dissipation, and quantum and thermal fluctuations. Control of these dynamics requires a detailed understanding of the mechanisms at play. Due to the number of degrees of freedom, …

Observation and Modulation of the Quantum Mpemba Effect on a Superconducting Quantum Processor
Yueshan Xu, Cai-Ping Fang, Bing-Jie Chen, Ming-Chuan Wang, Zi-Yong Ge, Yun-Hao Shi, Yu Liu, Cheng-Lin Deng, Kui Zhao, Zheng-He Liu, Tian-Ming Li, Hao Li, Ziting Wang, Gui-Han Liang, Da'er Feng, Xueyi Guo, Xu-Yang Gu, Yang He, Hao-Tian Liu, Zheng-Yang Mei, Yongxi Xiao, Yu Yan, Yi-Han Yu, Wei-Ping Yuan, Jia-Chi Zhang, Zheng-An Wang, Gangqin Liu, Xiaohui Song, Ye Tian, Yu-Ran Zhang, Shi-Xin …

Observation and Modulation of the Quantum Mpemba Effect on a Superconducting Quantum Processor
In non-equilibrium quantum many-body systems, the quantum Mpemba effect (QME) emerges as a counterintuitive phenomenon: systems exhibiting greater initial symmetry breaking restore symmetry faster than those with less. While theoretical exploration of QME has surged, experimental studies on its multidimensional modulation remain limited. Here, we report the observation and control of QME using a superconducting processor featuring a unique fully connected, tunable-coupling architecture that ena…

Steady state properties of periodically driven quantum systems
Milan \v{S}indelka, David Gelbwaser-Klimovsky
https://arxiv.org/abs/2508.07674 https://arxiv…

Steady state properties of periodically driven quantum systems
Periodic driving is used to steer physical systems to unique stationary states or nonequilibrium steady states (NESS), producing enhanced properties inaccessible to non-driven systems. For open quantum systems, characterizing the NESS is challenging and existing results are generally limited to specific types of driving and the Born-Markov approximation. Here we go beyond these limits by studying a generic periodically driven $ N$-level quantum system interacting with a low-density thermal gas.…

Estimating classical mutual information between quantum subsystems with neural networks
D. A. Konyshev, V. V. Mazurenko
https://arxiv.org/abs/2508.07652 https://

Estimating classical mutual information between quantum subsystems with neural networks
Characterizing correlations in a quantum system on the basis of the results of the projective measurements can be performed with different means including the calculation of the classical mutual information. Generally, estimating such information-entropy-based quantities requires having complete statistics of the system's states. Here we explore the possibility to reconstruct the classical mutual information and specific entropy of a quantum system with neural network approach on the basis of l…

Obfuscated Quantum and Post-Quantum Cryptography
Anju Rani, Xiaoyu Ai, Aman Gupta, Ravi Singh Adhikari, Robert Malaney
https://arxiv.org/abs/2508.07635 https://

Obfuscated Quantum and Post-Quantum Cryptography
In this work, we present an experimental deployment of a new design for combined quantum key distribution (QKD) and post-quantum cryptography (PQC). Novel to our system is the dynamic obfuscation of the QKD-PQC sequence of operations, the number of operations, and parameters related to the operations; coupled to the integration of a GPS-free quantum synchronization protocol within the QKD process. We compare the performance and overhead of our QKD-PQC system relative to a standard QKD system wi…

Tomography-assisted noisy quantum circuit simulator using matrix product density operators
Wei-guo Ma, Yun-Hao Shi, Kai Xu, Heng Fan
https://arxiv.org/abs/2508.07610 https://

Tomography-assisted noisy quantum circuit simulator using matrix product density operators
In recent years, efficient quantum circuit simulations incorporating ideal noise assumptions have relied on tensor network simulators, particularly leveraging the matrix product density operator (MPDO) framework. However, experiments on real noisy intermediate-scale quantum (NISQ) devices often involve complex noise profiles, encompassing uncontrollable elements and instrument-specific effects such as crosstalk. To address these challenges, we employ quantum process tomography (QPT) techniques …

Error-Resilient Fast Entangling Gates for Scalable Ion-Trap Quantum Processors
Isabelle Savill-Brown, Zain Mehdi, Alexander K. Ratcliffe, Varun D. Vaidya, Haonan Liu, Simon A. Haine, C. Ricardo Viteri, Joseph J. Hope
https://arxiv.org/abs/2508.07593

Error-Resilient Fast Entangling Gates for Scalable Ion-Trap Quantum Processors
Non-adiabatic two-qubit gate proposals for trapped-ion systems offer superior performance and flexibility over adiabatic schemes at the cost of increased laser control requirements. Existing fast gate schemes are limited by single-qubit transition errors, which constrain the total number of pulses in high-fidelity solutions. We introduce an improved gate search scheme that enables both local and non-local two-qubit gates in chains containing tens of ions. These protocols use a multi-objective m…

Graded Quantum Codes: From Weighted Algebraic Geometry to Homological Chain Complexes
Tony Shaska
https://arxiv.org/abs/2508.07542 https://arxiv.org/pdf/25…

Graded Quantum Codes: From Weighted Algebraic Geometry to Homological Chain Complexes
We introduce graded quantum codes, unifying two classes of quantum error-correcting codes. The first, quantum weighted algebraic geometry (AG) codes, derives from rational points on hypersurfaces in weighted projective spaces over finite fields. This extends classical AG codes by adding weighted degrees and singularities, enabling self-orthogonal codes via the CSS method with improved distances using algebraic structures and invariants like weighted heights.The second class arises from chain co…

A Method for Constructing Quasi-Random Peaked Quantum Circuits
O. G. Udalov
https://arxiv.org/abs/2508.07491 https://arxiv.org/pdf/2508.07491

A Method for Constructing Quasi-Random Peaked Quantum Circuits
An algorithm is proposed for constructing quasi-random "peaked" quantum circuits, i.e., circuits whose final qubit state exhibits a high probability concentration on a specific computational basis state. These circuits consist of random gates arranged in a brick-wall architecture. While the multiqubit state in the middle of the circuit can exhibit significant entanglement, the final state is, with high probability, a predetermined pure bitstring. A technique is introduced to obscure the final b…

PHIP Sequences and Dipolar Fields
Martin C. Korzeczek, Ilai Schwartz, Martin B. Plenio
https://arxiv.org/abs/2508.07488 https://arxiv.org/pdf/2508.07488

PHIP Sequences and Dipolar Fields
Para-hydrogen induced polarization (PHIP) achieves efficient hyperpolarisation of nuclear spins with the transfer of the singlet order of parahydrogen to target molecules through catalytic hydrogenation reactions and subsequent coherent control of the spin dynamics. However, in realistic conditions B0/B1 inhomogeneities lead to significant reduction in the polarization transfer efficiency. Moreover, in high-concentration samples, dipolar fields arising from the magnetisation of the sample can d…

Quanutm-State Texture as a Resource: Measures and Nonclassical Interdependencies
Yuntao Cui, Zhaobing Fan, Sunho Kim
https://arxiv.org/abs/2508.07481 https://

Quanutm-State Texture as a Resource: Measures and Nonclassical Interdependencies
Quantum-state texture is a newly recognized quantum resource that has garnered attention with the advancement of quantum theory. In this work, we discuss several main tasks concerning quantum-state texture resource theory, including quantum-state texture measure, quantum state transformation under free operations, and relations between quantum resources. We first provide two new quantum-state texture measures and propose specific form of function for constructing quantum-state texture measures …

Universally Robust Control of Open Quantum Systems
Lixiang Ding, Jingtao Fan, Xingze Qiu
https://arxiv.org/abs/2508.07379 https://arxiv.org/pdf/2508.07379

Universally Robust Control of Open Quantum Systems
Mitigating noise-induced decoherence is the central challenge in controlling open quantum systems. While existing robust protocols often require precise noise models, we introduce a universal framework for noise-agnostic quantum control that achieves high-fidelity operations without prior environmental noise characterization. This framework capitalizes on the dynamical modification of the system-environment coupling through control drives, an effect rigorously encoded in the dynamical equation.…

Integrating Quantum Computing with Multiconfiguration Pair-Density Functional Theory for Biological Electron Transfer
Yibo Chen, Zirui Sheng, Weitang Li, Yong Zhang, Xun Xu, Jun-Han Huang, Yuxiang Li
https://arxiv.org/abs/2508.07359

Integrating Quantum Computing with Multiconfiguration Pair-Density Functional Theory for Biological Electron Transfer
Accurate calculation of strongly correlated electronic systems requires proper treatment of both static and dynamic correlations, which remains challenging for conventional methods. To address this, we present VQE-PDFT, a quantum-classical hybrid framework that integrates variational quantum eigensolver with multiconfiguration pair-density functional theory (MC-PDFT). This framework strategically employs quantum circuits for multiconfigurational wavefunction representation while utilizing densi…

Quantum MIMO Diversity over Discrete-Variable Crosstalk Channels
Shehbaz Tariq, Junaid ur Rehman, Symeon Chatzinotas
https://arxiv.org/abs/2508.07344 https://

Quantum MIMO Diversity over Discrete-Variable Crosstalk Channels
Quantum communication plays a pivotal role in enabling distributed quantum computing and sensing. Diversity strategies can be used to increase the communication reliability (in the sense of output fidelity with respect to the input quantum state) when multiple communication channels are available. The current paper proposes a diversity strategy for quantum discrete variable (DV) multiple-input-multiple-output (MIMO) channels, utilizing approximate cloning to distribute information across multip…

The simplest Kochen-Specker set
Ad\'an Cabello
https://arxiv.org/abs/2508.07335 https://arxiv.org/pdf/2508.07335

The simplest Kochen-Specker set
Kochen-Specker (KS) sets are fundamental in physics. Every time nature produces bipartite correlations attaining the nonsignaling limit, or two parties always win a nonlocal game impossible to always win classically, is because the parties are measuring a KS set. The simplest quantum system in which all these phenomena occur is a pair of three-level systems. However, the simplest KS sets in dimension three known are asymmetrical and require a large number of bases (the current minimum is 16, se…

Information in quantum field theory simulators: Thin-film superfluid helium
Maciej T. Jarema, Cameron R. D. Bunney, Vitor S. Barroso, Mohammadamin Tajik, Chris Goodwin, Silke Weinfurtner
https://arxiv.org/abs/2508.07247

Information in quantum field theory simulators: Thin-film superfluid helium
Understanding quantum correlations through information-theoretic measures is fundamental to developments in quantum field theory, quantum information, and quantum many-body physics. A central feature in a plethora of systems is the area law, under which information scales with the size of the boundary of the system, rather than volume. Whilst many systems and regimes exhibiting an area law have been identified theoretically, experimental verification remains limited, particularly in continuous …

Squeezed Coherent States in Supersymmetric Quantum Mechanics with Position-Dependent Mass
Daniel Sabi Takou, Amidou Boukari, Assimiou Yarou Mora, Gabriel Y. H. Avossevou
https://arxiv.org/abs/2508.07228

Squeezed Coherent States in Supersymmetric Quantum Mechanics with Position-Dependent Mass
In this paper, we construct and analyze a class of squeezed coherent states within the framework of supersymmetric quantum mechanics (SUSYQM) involving a position-dependent mass (PDM). Using a deformed algebraic structure, we generalize the creation and annihilation operators to accommodate spatially varying mass profiles. The resulting states exhibit non-classical features, such as squeezing, coherence, and modified uncertainty relations, strongly influenced by both the deformation parameter…

Positive-divisibility of Subsystems in Quantum Dynamics
Anumita Mukhopadhyay, Praggnyamita Ghosh, Shibdas Roy
https://arxiv.org/abs/2508.07188 https://arxi…

Positive-divisibility of Subsystems in Quantum Dynamics
It is known that the existence of memory effect can revive quantum correlations in open system dynamics. In this regard, the backflow of information from environment to the system can be identified with Complete Positive (CP) indivisibility as well as Positive (P) indivisibility criteria. It is also known that if a quantum system is CP-divisible, it can also have memory effect which can be witnessed by P-indivisibility. Here, we have explored the relation of P-divisibility with unitality condit…

Bargmann invariants of Gaussian states
Jianwei Xu
https://arxiv.org/abs/2508.07155 https://arxiv.org/pdf/2508.07155…

Bargmann invariants of Gaussian states
Given a set of ordered quantum states, described by density operators $% \{ρ_{j}\}_{j=1}^{n}$, the Bargmann invariant of $\{ρ_{j}\}_{j=1}^{n}$ is defined as tr($ρ_{1}ρ_{2}...ρ_{n}$). Bargmann invariant serves as a fundamental concept for quantum mechanics and has diverse applications in quantum information science. Bosonic Gaussian states are a class of quantum states on infinite-dimensional Hilbert space, widely used in quantum optics and quantum information science. Bosonic Gaussian stat…

Optimal Quantum Estimation with Stabilizer-Based Local Measurements
Jia-Xuan Liu, Hai-Long Shi, Chunfeng Wu, Sixia Yu
https://arxiv.org/abs/2508.07150 https://

Optimal Quantum Estimation with Stabilizer-Based Local Measurements
A central challenge in quantum metrology is to identify optimal protocols under measurement constraints that reflect realistic experimental conditions, e.g., local measurements in multipartite scenarios. Here, we present a sufficient criterion for metrological schemes to saturate the quantum Cramér-Rao bound (QCRB) using local measurements, based on stabilizer formalism. In ideal settings, we show that graph states always admit local estimation protocols with an optimal estimation precision de…

Block encoding the 3D heterogeneous Poisson equation with application to fracture flow
Austin Pechan, John Golden, Daniel O'Malley
https://arxiv.org/abs/2508.07125 https://

Block encoding the 3D heterogeneous Poisson equation with application to fracture flow
Quantum linear system (QLS) algorithms offer the potential to solve large-scale linear systems exponentially faster than classical methods. However, applying QLS algorithms to real-world problems remains challenging due to issues such as state preparation, data loading, and efficient information extraction. In this work, we study the feasibility of applying QLS algorithms to solve discretized three-dimensional heterogeneous Poisson equations, with specific examples relating to groundwater flow …

Low Cost Bayesian Experimental Design for Quantum Frequency Estimation with Decoherence
Alexandra Ram\^oa, Lu\'is Paulo Santos, Akihito Soeda
https://arxiv.org/abs/2508.07120

Low Cost Bayesian Experimental Design for Quantum Frequency Estimation with Decoherence
A two-level quantum system evolving under a time-independent Hamiltonian produces oscillatory measurement probabilities. The estimation of the associated frequency is a cornerstone problem in quantum metrology, sensing, calibration and control. In this work, we tackle this task by introducing WES: a Window Expansion Strategy for low cost adaptive Bayesian experimental design. WES employs empirical cost-reduction techniques to keep the optimization overhead low, curb scaling problems, and enable…

QuProFS: An Evolutionary Training-free Approach to Efficient Quantum Feature Map Search
Yaswitha Gujju, Romain Harang, Chao Li, Tetsuo Shibuya, Qibin Zhao
https://arxiv.org/abs/2508.07104

QuProFS: An Evolutionary Training-free Approach to Efficient Quantum Feature Map Search
The quest for effective quantum feature maps for data encoding presents significant challenges, particularly due to the flat training landscapes and lengthy training processes associated with parameterised quantum circuits. To address these issues, we propose an evolutionary training-free quantum architecture search (QAS) framework that employs circuit-based heuristics focused on trainability, hardware robustness, generalisation ability, expressivity, complexity, and kernel-target alignment. By…

Geometry-Controlled Freezing and Revival of Bell Nonlocality through Environmental Memory
Mohamed Hatifi
https://arxiv.org/abs/2508.07046 https://arxiv.org…

Geometry-Controlled Freezing and Revival of Bell Nonlocality through Environmental Memory
We show that the distance between two qubits coupled to a structured reservoir acts as a single geometric control that can store, revive, or suppress Bell nonlocality. In a mirror-terminated guide, quantum correlations lost to the bath return at discrete recurrence times, turning a product state into a Bell-violating one without any entangling drive (only local basis rotations/readout). In the continuum limit, we derive closed-form criteria for the emergence of nonlocality from backflow, and in…

Bridging Classical and Quantum Computing for Next-Generation Language Models
Yi Pan, Hanqi Jiang, Junhao Chen, Yiwei Li, Huaqin Zhao, Lin Zhao, Yohannes Abate, Yingfeng Wang, Tianming Liu
https://arxiv.org/abs/2508.07026

Bridging Classical and Quantum Computing for Next-Generation Language Models
Integrating Large Language Models (LLMs) with quantum computing is a critical challenge, hindered by the severe constraints of Noisy Intermediate-Scale Quantum (NISQ) devices, including barren plateaus and limited coherence. Current approaches often fail due to static quantum-classical partitioning. We introduce Adaptive Quantum-Classical Fusion (AQCF), the first framework to bridge this gap through dynamic, quantum-classical co-design. AQCF's core principle is real-time adaptation: it analyzes…

A Quantum Walk-Driven Algorithm for the Minimum Spanning Tree Problem under a Maximal Degree Constraint
F. S. Luiz, F. F. Fanchini, Victor Hugo C. de Albuquerque, J. P. Papa, M. C. de Oliveira
https://arxiv.org/abs/2508.07007

A Quantum Walk-Driven Algorithm for the Minimum Spanning Tree Problem under a Maximal Degree Constraint
We present a novel quantum walk-based approach to solve the Minimum Spanning Tree (MST) problem under a maximal degree constraint (MDC). By recasting the classical MST problem as a quantum walk on a graph, where vertices are encoded as quantum states and edge weights are inverted to define a modified Hamiltonian, we demonstrate that the quantum evolution naturally selects the MST by maximizing the cumulative transition probability (and thus the Shannon entropy) over the spanning tree. Our metho…