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Recently, quantum-state representation using artificial neural networks has started to be recognized as a powerful tool. However, due to the black-box nature of machine learning, it is difficult to analyze what machine learns or why it is…

Quantum Physics · Physics 2022-05-24 Yusuke Nomura

If a quantum system is subject to noise, it is possible to perform quantum error correction reversing the action of the noise if and only if no information about the system's quantum state leaks to the environment. In this article, we…

Quantum Physics · Physics 2012-07-06 Patrick Hayden , Andreas Winter

Characterizing and understanding noise affecting quantum states has immense benefits in spectroscopy as well as in realizing quantum devices. Transverse relaxation times under a set of dynamical decoupling (DD) sequences with varying…

Quantum Physics · Physics 2017-01-11 Deepak Khurana , Govind Unnikrishnan , T. S. Mahesh

Near-term quantum computers are noisy, and therefore must run algorithms with a low circuit depth and qubit count. Here we investigate how noise affects a quantum neural network (QNN) for state discrimination, applicable on near-term…

Quantum Physics · Physics 2021-01-27 Andrew Patterson , Hongxiang Chen , Leonard Wossnig , Simone Severini , Dan Browne , Ivan Rungger

We study the dynamics of quantum dissension for three qubit states in various dissipative channels such as amplitude damping, dephasing and depolarizing. Our study is solely based on Markovian environments where quantum channels are without…

Quantum Physics · Physics 2014-12-01 Pratik K. Sarangi , Indranil Chakrabarty

Understanding the dynamics of quantum correlations in many-body systems is a central problem in non-equilibrium quantum physics. We study the spread of mixed-state entanglement in a minimal model of quantum chaos, the kicked field Ising…

Quantum Physics · Physics 2026-03-17 Tanay Pathak

The competition between non-commuting projective measurements in discrete quantum circuits can give rise to entanglement transitions. It separates a regime where initially stored quantum information survives the time evolution from a regime…

Quantum Physics · Physics 2023-06-21 Felix Roser , Hans Peter Büchler , Nicolai Lang

In this paper, we address the problem of state communication in finite-level quantum systems through noise-affected channels. Our approach is based on a self-consistent theory of decoding inner products associated with the code and error…

Quantum Physics · Physics 2025-06-06 Jorge R. Bolaños-Servín , Yuriko Pitones , Josué I. Rios-Cangas

The task of testing whether two uncharacterized quantum devices behave in the same way is crucial for benchmarking near-term quantum computers and quantum simulators, but has so far remained open for continuous-variable quantum systems. In…

Quantum Physics · Physics 2023-05-29 Ya-Dong Wu , Yan Zhu , Ge Bai , Yuexuan Wang , Giulio Chiribella

The problem of estimating an unknown phase $ \varphi $ using two-level probes in the presence of unital phase-covariant noise and using finite resources is investigated. We introduce a simple model in which the phase-imprinting operation on…

Quantum Physics · Physics 2016-10-05 Rosanna Nichols , Thomas R. Bromley , Luis A. Correa , Gerardo Adesso

Symmetry breaking plays a central role in classifying the phases of quantum many-body systems. Recent developments have highlighted a novel symmetry-breaking pattern, in which the strong symmetry of a density matrix spontaneously breaks to…

Quantum Physics · Physics 2026-01-26 Ning Sun , Pengfei Zhang , Lei Feng

Quantum computing is a game-changing technology for global academia, research centers and industries including computational science, mathematics, finance, pharmaceutical, materials science, chemistry and cryptography. Although it has seen…

Quantum Physics · Physics 2023-03-07 He-Liang Huang , Xiao-Yue Xu , Chu Guo , Guojing Tian , Shi-Jie Wei , Xiaoming Sun , Wan-Su Bao , Gui-Lu Long

A quantum computer will use the properties of quantum physics to solve certain computational problems much faster than otherwise possible. One promising potential implementation is to use superconducting quantum bits in the circuit quantum…

Quantum Physics · Physics 2013-12-01 Matthew Reed

Quantum states inevitably decay with time into a probabilistic mixture of classical states, due to their interaction with the environment and measurement instrumentation. We present the first measurement of the decoherence dynamics of…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 H. Wang , M. Hofheinz , M. Ansmann , R. C. Bialczak , Erik Lucero , M. Neeley , A. D. O'Connell , D. Sank , M. Weides , J. Wenner , A. N. Cleland , John M. Martinis

Quantum error correction is widely believed to be essential for large-scale quantum computation, but the required qubit overhead remains a central challenge. Quantum low-density parity-check codes can substantially reduce this overhead…

Quantum Physics · Physics 2026-05-13 Chen Zhao , Casey Duckering , Andi Gu , Nishad Maskara , Hengyun Zhou

The most common error models for quantum computers assume the independence of errors on different qubits. However, most noise mechanisms have some correlations in space. We show how to improve quantum information processing for few-qubit…

Quantum Physics · Physics 2018-12-19 Vickram N. Premakumar , Robert Joynt

Surface codes$\unicode{x2014}$leading candidates for quantum error correction (QEC)$\unicode{x2014}$and entanglement phases$\unicode{x2014}$a key notion for many-body quantum dynamics$\unicode{x2014}$have heretofore been unrelated. Here, we…

Quantum Physics · Physics 2024-02-06 Jan Behrends , Florian Venn , Benjamin Béri

Fault tolerant quantum computers will require efficient co-processors for real-time decoding of their adopted quantum error correction protocols. In this work we examine the possibility of using specialised Ising model hardware to perform…

Quantum Physics · Physics 2019-03-26 Joschka Roffe , Stefan Zohren , Dominic Horsman , Nicholas Chancellor

Sensing and measurement tasks in severely adverse conditions such as loss, noise and dephasing can be improved by illumination with quantum states of light. Previous results have shown a modest reduction in the number of measurements…

Quantum Physics · Physics 2022-02-16 Alex O. C. Davis , Giacomo Sorelli , Valerian Thiel , Brian J. Smith

High-fidelity decoding of quantum error correction codes relies on an accurate experimental model of the physical errors occurring in the device. Because error probabilities can depend on the context of the applied operations, the error…