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The rates of quantum cryptographic protocols are usually expressed in terms of a conditional entropy minimized over a certain set of quantum states. In particular, in the device-independent setting, the minimization is over all the quantum…

Quantum Physics · Physics 2022-10-05 Peter Brown , Hamza Fawzi , Omar Fawzi

We employ a machine learning-enabled approach to quantum state engineering based on evolutionary algorithms. In particular, we focus on superconducting platforms and consider a network of qubits -- encoded in the states of artificial atoms…

Quantum Physics · Physics 2023-01-26 Jonathon Brown , Mauro Paternostro , Alessandro Ferraro

The generic bound of quantum speed limit time (the minimal evolution time) for a qubit system interacting with structural environment is investigated. We define a new bound for the quantum speed limit. It is shown that the non-Markovianity…

Quantum Physics · Physics 2015-09-23 Shao-xiong Wu , Yang Zhang , Chang-shui Yu , He-shan Song

The quantum correlations between a qubit and its environment are described quantitatively in terms of interatomic distance. Specifically, considering a realistic system of two two-level atoms and taking into account the dipole-dipole…

Quantum Physics · Physics 2015-06-05 K. Berrada , F. F. Fanchini , S. Abdel-Khalek

Many quantum information measures can be written as an optimization of the quantum relative entropy between sets of states. For example, the relative entropy of entanglement of a state is the minimum relative entropy to the set of separable…

Quantum Physics · Physics 2018-08-09 Hamza Fawzi , Omar Fawzi

There is no unique way to encode a quantum algorithm into a quantum circuit. With limited qubit counts, connectivity, and coherence times, a quantum circuit optimization is essential to make the best use of near-term quantum devices. We…

We consider the problem of reversing quantum dynamics, with the goal of preserving an initial state's quantum entanglement or classical correlation with a reference system. We exhibit an approximate reversal operation, adapted to the…

Quantum Physics · Physics 2026-01-21 H. Barnum , E. Knill

The maximal evolution speed of a quantum system can be represented by quantum speed limit time (QSLT).We investigate QSLT of a two-qubit system passing through a correlated channel (amplitude damping, phase damping, and depolarizing).By…

Quantum Physics · Physics 2019-11-20 Kai Xu , Guo-Feng Zhang , Wu-Ming Liu

Revivals of quantum correlations have often been explained in terms of back-action on quantum systems by their quantum environment(s). Here we consider a system of two independently evolving qubits, each locally interacting with a classical…

Quantum Physics · Physics 2012-03-19 Rosario Lo Franco , Bruno Bellomo , Erika Andersson , Giuseppe Compagno

To achieve fast computation, it is crucial to reset the memory to a desired state within a limited time. However, the inherent delay in the system's response often prevents reaching the desired state once the control process is completed in…

Statistical Mechanics · Physics 2024-09-17 Geng Li , Hui Dong

A powerful control method in experimental quantum computing is the use of spin echoes, employed to select a desired term in the system's internal Hamiltonian, while refocusing others. Here we address a more general problem, describing a…

Quantum Physics · Physics 2020-03-04 Gaurav Bhole , Takahiro Tsunoda , Peter J. Leek , Jonathan A. Jones

The entanglement evolution after a quantum quench became one of the tools to distinguish integrable versus chaotic (non-integrable) quantum many-body dynamics. Following this line of thoughts, here we propose that the revivals in the…

Statistical Mechanics · Physics 2020-09-01 Ranjan Modak , Vincenzo Alba , Pasquale Calabrese

The sensitivity of classical and quantum sensing is impaired in a noisy environment. Thus, one of the main challenges facing sensing protocols is to reduce the noise while preserving the signal. State of the art quantum sensing protocols…

Optics · Physics 2016-07-18 L. Cohen , Y. Pilnyak , D. Istrati , A. Retzker , H. S. Eisenberg

Recent technological developments have focused the interest of the quantum computing community on investigating how near-term devices could outperform classical computers for practical applications. A central question that remains open is…

Quantum Physics · Physics 2021-11-24 Daniel Stilck Franca , Raul Garcia-Patron

We investigate the dynamics of open quantum systems which are initially correlated with their environment. The strategy of our approach is to analyze how given, fixed initial correlations modify the evolution of the open system with respect…

Quantum Physics · Physics 2022-12-21 Alessandra Colla , Niklas Neubrand , Heinz-Peter Breuer

Setting the minimal-time bound for a quantum system to evolve between two distinguishable states, the quantum speed limit (QSL) characterizes the latent capability in speeding up of the system. It has found applications in determining the…

Quantum Physics · Physics 2023-02-02 Wei Wu , Jun-Hong An

Quantum mechanics dictates the band-structure of materials that is essential for functional electronic components. With increased miniaturization of devices, it becomes possible to exploit the full potential of quantum mechanics through the…

Quantum Physics · Physics 2022-05-26 Kasper Poulsen , Alan C. Santos , Lasse B. Kristensen , Nikolaj T. Zinner

Quantum technologies are developing powerful tools to generate and manipulate coherent superpositions of different energy levels. Envisaging a new generation of energy-efficient quantum devices, here we explore how coherence can be…

Quantum Physics · Physics 2017-09-06 Giulio Chiribella , Yuxiang Yang

We study the stability of entanglement in a quantum computer implementing an efficient quantum algorithm, which simulates a quantum chaotic dynamics. For this purpose, we perform a forward-backward evolution of an initial state in which two…

Quantum Physics · Physics 2007-05-23 Davide Rossini , Giuliano Benenti , Giulio Casati

In this article we explore a modification in the problem of controlling the rotation of a two level quantum system from an initial state to a final state in minimum time. Specifically we consider the case where the qubit is being weakly…

Quantum Physics · Physics 2012-11-09 Srinivas Sridharan
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