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»Cyber-Vorhängeschlösser knacken – Warum Quantencomputer ein Problem für die #Verschlüsselung bedeuten:
#Kryptografen wünschen sich Verschlüsselungssysteme, die auch für die #Quantencomputer

Cyber-Vorhängeschlösser knacken: Warum Quantencomputer ein Problem für die Verschlüsselung bedeuten -
Kryptografen wünschen sich Verschlüsselungssysteme, die auch für die Quantencomputer von morgen unmöglich zu knacken sind. Doch der Erfolg eines chinesischen Forscherteams zeigt, wo der Haken liegt. Unser Vertrauen in die Online-Sicherheit gründet fest in der Mathematik. Doch angesichts von Meldungen wie dieser, scheint das jetzt zu bröckeln: Einem Team aus Shanghai um Wang Chao, wie […]

Sequential Quantum Computing
Sebasti\'an V. Romero, Alejandro Gomez Cadavid, Enrique Solano, Narendra N. Hegade
https://arxiv.org/abs/2506.20655 https:…

Sequential Quantum Computing
We propose and experimentally demonstrate sequential quantum computing (SQC), a paradigm that utilizes multiple homogeneous or heterogeneous quantum processors in hybrid classical-quantum workflows. In this manner, we are able to overcome the limitations of each type of quantum computer by combining their complementary strengths. Current quantum devices, including analog quantum annealers and digital quantum processors, offer distinct advantages, yet face significant practical constraints when …

PhasePoly: An Optimization Framework forPhase Polynomials in Quantum Circuits
Zihan Chen, Henry Chen, Yuwei Jin, Minghao Guo, Enhyeok Jang, Jiakang Li, Caitlin Chan, Won Woo Ro, Eddy Z. Zhang
https://arxiv.org/abs/2506.20624

PhasePoly: An Optimization Framework forPhase Polynomials in Quantum Circuits
Quantum computing has transformative computational power to make classically intractable computing feasible. As the algorithms that achieve practical quantum advantage are beyond manual tuning, quantum circuit optimization has become extremely important and integrated into today's quantum software stack. This paper focuses on a critical type of quantum circuit optimization -- phase-polynomial optimization. Phase polynomials represents a class of building-block circuits that appear frequently in…

Quantum aspects of spacetime: A quantum optics view of acceleration radiation and black holes
C. R. Ordonez, A. Chakraborty, H. E. Camblong, M. O. Scully, W. G. Unruh
https://arxiv.org/abs/2508.17401

Quantum aspects of spacetime: A quantum optics view of acceleration radiation and black holes
For the centennial of quantum mechanics, we offer an overview of the central role played by quantum information and thermalization in problems involving fundamental properties of spacetime and gravitational physics. This is an open area of research still a century after the initial development of formal quantum mechanics, highlighting the effectiveness of quantum physics in the description of all natural phenomena. These remarkable connections can be highlighted with the tools of modern quantum…

Efficient and optimal quantum state discrimination via quantum belief propagation
Christophe Piveteau, Joseph M. Renes
https://arxiv.org/abs/2509.19441 https://

Efficient and optimal quantum state discrimination via quantum belief propagation
We present an efficient quantum algorithm for a structured state discrimination problem we call the subspace decoding task. Building on this, we show that the algorithm enables efficient and optimal decoding of certain families of structured classical linear codes transmitted over binary-input classical-quantum pure-state channels. Such decoders can substantially enhance the performance of quantum algorithms based on Regev's reduction, such as decoded quantum interferometry. In particular, we o…

Quantum Fisher information as a witness of non-Markovianity and criticality in the spin-boson model
Daniele Parlato, Grazia Di Bello, Fabrizio Pavan, Giulio De Filippis, Carmine Antonio Perroni
https://arxiv.org/abs/2508.16413

Quantum Fisher information as a witness of non-Markovianity and criticality in the spin-boson model
The quantum Fisher information, the quantum analogue of the classical Fisher information, is a central quantity in quantum metrology and quantum sensing because of its connection to parameter estimation and fidelity susceptibility. Using numerically exact methods applied to a paradigmatic open quantum system, the spin-boson model, we calculate both static and dynamical quantum Fisher information matrix elements with respect to spin-bath couplings and magnetic field strengths. As the spin-bath i…

Quantum Paths: a Quantum Walk approach
Claudio Pellitteri, Marcello Caleffi, Angela Sara Cacciapuoti
https://arxiv.org/abs/2508.18077 https://arxiv.org/pdf…

Quantum Paths: a Quantum Walk approach
The quantum switch, a process enabling a coherent superposition of different orders of quantum channels, has garnered significant attention due to its ability to enable noiseless communications through noisy channels, such as entanglement-breaking channels. However, its practical implementation and scalability remain challenging. In contrast, the spatial superposition of quantum channels is more accessible experimentally and has been shown to enhance channel capacity, although it does not match…

Quantum speed limits based on Jensen-Shannon and Jeffreys divergences for general physical processes
Jucelino Ferreira de Sousa, Diego Paiva Pires
https://arxiv.org/abs/2509.20347

Quantum speed limits based on Jensen-Shannon and Jeffreys divergences for general physical processes
We discuss quantum speed limits (QSLs) for finite-dimensional quantum systems undergoing a general physical process. These QSLs were obtained using two families of entropic measures, namely the square root of the Jensen-Shannon divergence, which in turn defines a faithful distance of quantum states, and the square root of the quantum Jeffreys divergence. The results apply to both closed and open quantum systems, and are evaluated in terms of the Schatten speed of the evolved state, as well as c…

A digital twin of atomic ensemble quantum memories
Elizabeth Robertson, Benjamin Maa{\ss}, Konrad Tschernig, Janik Wolters
https://arxiv.org/abs/2506.20403

A digital twin of atomic ensemble quantum memories
Accurate performance estimation of experimentally demonstrated quantum memories is key to understand the nuances in their deployment in photonic quantum networks. While several software packages allow for accessible quantum simulation, they often do not account for the loss and noise in physical devices. We present a framework for modeling ensemble-based atomic quantum memories using the quantum channel formalism. We provide a Kraus matrix representation of several experimentally implemented st…

Low-rank optimal control of quantum devices
Leo Goutte, Vincenzo Savona
https://arxiv.org/abs/2508.18114 https://arxiv.org/pdf/2508.18114

Low-rank optimal control of quantum devices
Quantum optimal control is essential for designing high-fidelity quantum operations, but computational demands often limit its application to realistic quantum devices. We apply a computational framework that dramatically reduces the computational cost while maintaining predictive accuracy through the low-rank approximation for simulating open quantum system dynamics. The key insight is that most quantum operation protocols maintain the system in nearly pure states throughout their execution. T…