Tootfinder

Observer Time from Causality in Perturbative Quantum Gravity
Allic Sivaramakrishnan
https://arxiv.org/abs/2506.16109 https://arxiv.or…

Observer Time from Causality in Perturbative Quantum Gravity
It is unclear whether an observable notion of time exists in quantum gravity even in principle because spacetime itself fluctuates. We propose a form of observable time in perturbative quantum gravity. First, we define an elapsed proper time in curved space using intersections of worldlines and future light cones. Here, time arises from causality via the dependence on light cones. We then propose that performing the gravitational path integral describes quantum gravity corrections to this notio…

Will it glue? On short-depth designs beyond the unitary group
Lorenzo Grevink, Jonas Haferkamp, Markus Heinrich, Jonas Helsen, Marcel Hinsche, Thomas Schuster, Zolt\'an Zimbor\'as
https://arxiv.org/abs/2506.23925

Will it glue? On short-depth designs beyond the unitary group
We provide a range of results on several groups of broad interest in quantum information science: the Clifford group, the orthogonal group, the unitary symplectic groups, and the matchgate group. For all of these groups, we prove that analogues of unitary designs cannot be generated by any circuit ensemble with light-cones that are smaller than the system size. This implies linear lower bounds on the circuit depth in one-dimensional systems. For the Clifford and orthogonal group, we moreover sh…

Newman-Penrose-like exact and approximate conservation laws: a covariant and conformal formulation
Berend Schneider
https://arxiv.org/abs/2507.02237 https:…

Newman-Penrose-like exact and approximate conservation laws: a covariant and conformal formulation
Using a conformal extension of the Geroch-Held-Penrose (GHP) formalism I derive a manifestly covariant and conformal expression of Newman-Penrose (NP) constants, which are a set of conserved quantities associated to solutions to the wave equation on light cones in Minkowski space. The resulting expression generalizes to massless fields of arbitrary spin -- including the electromagnetic field, Weyl fermions, and the linearized Weyl tensor -- on conformally flat space-times. In some non-conformal…

Interferometric and Bipartite OTOC for Non-Markovian Open Quantum Spin-Chains and Lipkin-Meshkov-Glick Model
Baibhab Bose, Devvrat Tiwari, Subhashish Banerjee
https://arxiv.org/abs/2506.23796

Interferometric and Bipartite OTOC for Non-Markovian Open Quantum Spin-Chains and Lipkin-Meshkov-Glick Model
The information scrambling phenomena in an open quantum system modeled by Ising spin chains coupled to Lipkin-Meshkov-Glick (LMG) baths are observed via an interferometric method for obtaining out-of-time-ordered correlators ($\mathcal{F}-$OTOC). We also use an anisotropic bath connecting to a system of tilted field Ising spin chain in order to confirm that such situations are suitable for the emergence of ballistic spreading of information manifested in the light cones in the $\mathcal{F}-$OTO…