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Operator spreading under unitary time evolution has attracted a lot of attention recently, as a way to probe many-body quantum chaos. While quantities such as out-of-time-ordered correlators (OTOC) do distinguish interacting from…

Strongly Correlated Electrons · Physics 2021-09-17 Javier Lopez-Piqueres , Brayden Ware , Sarang Gopalakrishnan , Romain Vasseur

The standard model of quantum circuits assumes operations are applied in a fixed sequential "causal" order. In recent years, the possibility of relaxing this constraint to obtain causally indefinite computations has received significant…

Quantum Physics · Physics 2024-08-20 Alastair A. Abbott , Mehdi Mhalla , Pierre Pocreau

The temporal evolution of a quantum system can be characterized by quantum process tomography, a complex task that consumes a number of physical resources scaling exponentially with the number of subsystems. An alternative approach to the…

We present a Bounded Model Checking technique for higher-order programs. The vehicle of our study is a higher-order calculus with general references. Our technique is a symbolic state syntactical translation based on SMT solvers, adapted to…

Programming Languages · Computer Science 2018-04-06 Yu-Yang Lin , Nikos Tzevelekos

Quantum phase transitions (QPTs) in coherent Ising machines (CIMs) are studied via a spectral mapping between the one-dimensional XY spin model and a network of degenerate optical parametric oscillators (DOPOs). This exact correspondence…

Quantum Physics · Physics 2025-12-30 Jing-Yi-Ran Jin , Shuang-Quan Ma , Qing Ai

A set of new schemes for quantum computation and communication have been either designed or experimentally realized using optimal quantum resources. A multi-output quantum teleportation scheme, where a sender (Alice) teleports an m and…

Quantum Physics · Physics 2025-07-15 Satish Kumar

High-order quantum coherence reveals the statistical correlation of quantum particles. Manipulation of quantum coherence of light in temporal domain enables to produce single-photon source, which has become one of the most important quantum…

Out-of-time-order correlators (OTOCs) are central probes of quantum scrambling, and their generalizations have recently become key primitives for both benchmarking quantum advantage and learning the structure of Hamiltonians. Yet their…

Quantum Physics · Physics 2025-12-01 Keisuke Fujii

In this work, we present a protocol for comparing the performance of arbitrary quantum processes executed on spatially or temporally disparate quantum platforms using Local Operations and Classical Communication (LOCC). The protocol…

Quantum Physics · Physics 2024-01-05 Congcong Zheng , Xutao Yu , Kun Wang

The recent advancements in out-of-time-ordered correlator (OTOC) measurements have provided a promising pathway to explore quantum chaos and information scrambling. However, despite recent advancements, their experimental realization…

Quantum Physics · Physics 2025-02-25 Sabyasachi Chakraborty , Rohit Sarma Sarkar , Sonjoy Majumder

In this "map" we are going to present the concept of indefinite causal order and make a quick journey through its different flavours. We will start with a broad conceptual motivation for studying indefinite causal order, based on the…

Quantum Physics · Physics 2025-06-06 Jorge Escandón-Monardes

Any optical quantum information processing machine would be comprised of fully-characterized constituent devices for both single state manipulations and tasks involving the interaction between multiple quantum optical states. Ideally for…

Quantum Physics · Physics 2015-05-18 Connor Kupchak , Samuel Rind , Bertus Jordaan , Eden Figueroa

We construct higher-order curvature invariants in causal set quantum gravity. The motivation for this work is twofold: first, to characterize causal sets, discrete operators that encode geometric information on the emergent spacetime…

General Relativity and Quantum Cosmology · Physics 2023-02-01 Gustavo. P. de Brito , Astrid Eichhorn , Christopher Pfeiffer

The quantum statistical fluctuations of the electromagnetic field establish a limit, known as the shot-noise limit, on the sensitivity of optical measurements performed with classical technologies. However, quantum technologies are not…

In classical physics, events follow a definite causal order: the past influences the future, but not the reverse. Quantum theory, however, permits superpositions of causal orders -- so-called indefinite causal orders -- which can provide…

Quantum Physics · Physics 2026-04-29 Carla M. D. Richter , Michael Antesberger , Huan Cao , Philip Walther , Lee A. Rozema

Processes with indefinite causal order can arise when quantum theory is locally valid and they allow accomplishing new informational tasks. Despite recent progress, the correlations allowed in such processes have not been clearly…

Quantum Physics · Physics 2026-03-18 Zixuan Liu , Ognyan Oreshkov

Applying post selection in each step of an iterated protocol leads to sensitive quantum dynamics that may be utilized to test and benchmark current quantum computers. An example of this type of protocols was originally proposed for the task…

Quantum Physics · Physics 2024-10-10 Adrian Ortega , Orsolya Kálmán , Tamás Kiss

Recent developments in the formalisation of quantum causal structures have made it possible to test and compare hypotheses about causal structure empirically, rather than being a-priori assumptions. Such differences in causal structure may…

Quantum Physics · Physics 2026-05-28 Declan Maguire , Fabio Costa

It was recently found that the indefinite causal order in the quantum switch can be certified device-independently when assuming the impossibility of superluminal influences. Here we strengthen this result in two ways. First, we give a…

Quantum Physics · Physics 2024-12-04 Tein van der Lugt , Nick Ormrod

Quantum processes, such as quantum circuits, quantum memories, and quantum channels, are essential ingredients in almost all quantum information processing tasks. However, the characterization of these processes remains a daunting task due…

Quantum Physics · Physics 2020-04-16 Ye-Chao Liu , Jiangwei Shang , Xiao-Dong Yu , Xiangdong Zhang