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A semi-Markov process method for obtaining general counting statistics for open quantum systems is extended to the scenario of resetting. The simultaneous presence of random resets and wave function collapses means that the quantum jump…

Statistical Mechanics · Physics 2023-12-15 Fei Liu

We construct a large class of non-Markovian master equations that describe the dynamics of open quantum systems featuring strong memory effects, which relies on a quantum generalization of the concept of classical semi-Markov processes.…

Quantum Physics · Physics 2008-10-03 Heinz-Peter Breuer , Bassano Vacchini

Quantum process tomography (QPT) is a fundamental tool for fully characterizing quantum systems. It relies on querying a set of quantum states as input to the quantum process. Previous QPT methods typically employ a straightforward strategy…

Quantum Physics · Physics 2025-06-06 Jiaqi Yang , Xiaohua Xu , Wei Xie

In recent years, the detection of genuine multipartite entanglement (GME) via machine learning has received scant attention. Here, we employ convolutional neural networks (CNNs), as well as CNNs enhanced with squeeze-and-excitation (SE) to…

Quantum Physics · Physics 2025-08-20 Yi-Jun Luo , Xuan Leng , Chengjie Zhang

We study a classical model for the accumulation of errors in multi-qubit quantum computations. By modeling the error process in a quantum computation using two coupled Markov chains, we are able to capture a weak form of time-dependency…

Quantum Physics · Physics 2021-04-26 Long Ma , Jaron Sanders

We present a quantum-classical hybrid algorithm that simulates electronic structures of periodic systems such as ground states and quasiparticle band structures. By extending the unitary coupled cluster (UCC) theory to describe crystals in…

Quantum Physics · Physics 2022-02-16 Nobuyuki Yoshioka , Takeshi Sato , Yuya O. Nakagawa , Yu-ya Ohnishi , Wataru Mizukami

The mapping of fermionic states onto qubit states, as well as the mapping of fermionic Hamiltonian into quantum gates enables us to simulate electronic systems with a quantum computer. Benefiting the understanding of many-body systems in…

Quantum Physics · Physics 2018-10-12 Mark Steudtner , Stephanie Wehner

We find the conditions under which a quantum regression theorem can be assumed valid for non-Markovian master equations consisting in Lindblad superoperators with memory kernels. Our considerations are based on a generalized Born-Markov…

Quantum Physics · Physics 2008-03-18 Adrian A. Budini

Scaling quantum computers, i.e., quantum processing units (QPUs) to enable the execution of large quantum circuits is a major challenge, especially for applications that should provide a quantum advantage over classical algorithms. One…

Quantum Physics · Physics 2026-01-27 Leo Sünkel , Jonas Stein , Jonas Nüßlein , Tobias Rohe , Claudia Linnhoff-Popien

Reconstructing quantum states is an important task for various emerging quantum technologies. The process of reconstructing the density matrix of a quantum state is known as quantum state tomography. Conventionally, tomography of arbitrary…

Quantum Physics · Physics 2020-08-17 Sanjib Ghosh , Andrzej Opala , Michał Matuszewski , Tomasz Paterek , Timothy C. H. Liew

We demonstrate the application of pattern recognition algorithms via hidden Markov models (HMM) for qubit readout. This scheme provides a state-path trajectory approach capable of detecting qubit state transitions and makes for a robust…

Quantum Physics · Physics 2021-01-04 Luis A. Martinez , Yaniv J. Rosen , Jonathan L. DuBois

We prove classical simulation hardness, under the generalized $\mathsf{P}\neq\mathsf{NP}$ conjecture, for quantum circuit families with applications in near-term chemical ground state estimation. The proof exploits a connection to particle…

Quantum Physics · Physics 2026-02-06 Oskar Leimkuhler , K. Birgitta Whaley

We consider entanglement detection for quantum key distribution systems that use two signal states and continuous variable measurements. This problem can be formulated as a separability problem in a qubit-mode system. To verify…

Quantum Physics · Physics 2007-05-23 Johannes Rigas , Otfried Gühne , Norbert Lütkenhaus

Quantum state tomography (QST) allows for the reconstruction of quantum states through measurements and some inference technique under the assumption of repeated state preparations. Bayesian inference provides a promising platform to…

Quantum Physics · Physics 2025-05-22 Hanson H. Nguyen , Kody J. H. Law , Joseph M. Lukens

Programmable quantum devices are now able to probe wave functions at unprecedented levels. This is based on the ability to project the many-body state of atom and qubit arrays onto a measurement basis which produces snapshots of the system…

We propose a new classification scheme for quantum entanglement based on topological links. This is done by identifying a non-rigid ring to a particle, attributing the act of cutting and removing a ring to the operation of tracing out the…

Quantum Physics · Physics 2018-04-09 Gonçalo M. Quinta , Rui André

Identifying the nonlocality of a multiparty quantum state is an important task in quantum mechanics. Seevinck and Svetlichny [Phys. Rev. Lett. 89, 060401 (2002)], and independently, Collins and co-workers [Phys. Rev. Lett. 88, 170405…

Quantum Physics · Physics 2023-10-20 Sk Sahadat Hossain , Biswajit Paul , Indrani Chattopadhyay , Debasis Sarkar

Quantum state sharing is a protocol where perfect reconstruction of quantum states is achieved with incomplete or partial information in a multi-partite quantum networks. Quantum state sharing allows for secure communication in a quantum…

In a recent paper ([1]=quant-ph/0606035) it is shown how the optimal recovery operation in an error correction scheme can be considered as a semidefinite program. As a possible future improvement it is noted that still better error…

Quantum Physics · Physics 2007-05-23 M. Reimpell , R. F. Werner , K. Audenaert

Markov chain methods are remarkably successful in computational physics, machine learning, and combinatorial optimization. The cost of such methods often reduces to the mixing time, i.e., the time required to reach the steady state of the…

Quantum Physics · Physics 2018-11-15 Davide Orsucci , Hans J. Briegel , Vedran Dunjko