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In this set of five lectures the authors have presented techniques to analyze open classical and quantum systems using correlation matrices. For diverse reasons we shall see that random matrices play an important role to describe a null…

Mathematical Physics · Physics 2014-02-12 Vinayak , Thomas H. Seligman

Characterising the time over which quantum coherence survives is critical for any implementation of quantum bits, memories and sensors. The usual method for determining a quantum system's decoherence rate involves a suite of experiments…

The stability of quantum systems to perturbations of the Hamiltonian is studied. This stability is quantified by the fidelity. Dependence of fidelity on the initial state as well as on the dynamical properties of the system is considered.…

Quantum Physics · Physics 2007-05-23 Marko Znidaric

In this article, we study the problem of designing a Decoherence Control for quantum systems with the help of a scalable ancillary quantum control and techniques from geometric control theory, in order to successfully and completely…

Quantum Physics · Physics 2015-03-14 Narayan Ganesan , Tzyh-Jong Tarn

We analyse dissipation in quantum computation and its destructive impact on efficiency of quantum algorithms. Using a general model of decoherence, we study the time evolution of a quantum register of arbitrary length coupled with an…

Quantum Physics · Physics 2015-06-26 G. Massimo Palma , Kalle-Antti Suominen , Artur K. Ekert

The primary consideration in developing new material platforms for quantum applications is to optimize coherence. Despite its importance, decoherence processes remains challenging to experimentally interrogate and quantify. In this…

Quantum Physics · Physics 2025-09-25 Albert Liu , Matthew W. Day , Steven T. Cundiff

Quantum processors can already execute tasks beyond the reach of classical simulation, albeit for artificial problems. At this point, it is essential to design error metrics that test the experimental accuracy of quantum algorithms with…

Quantum Physics · Physics 2024-01-22 Jader P. Santos , Ivan Henao , Raam Uzdin

A density matrix describes the statistical state of a quantum system. It is a powerful formalism to represent both the quantum and classical uncertainty of quantum systems and to express different statistical operations such as measurement,…

Machine Learning · Computer Science 2024-05-01 Fabio A. González , Alejandro Gallego , Santiago Toledo-Cortés , Vladimir Vargas-Calderón

This paper is a pedagogical yet critical introduction to the quantum description of unstable systems, mostly at the level of a graduate quantum mechanics course. Quantum decays appear in many different fields of physics, and their…

Quantum Physics · Physics 2019-01-30 Charis Anastopoulos

We propose and discuss two conjectures on the nature of information leaks (decoherence) for quantum computers. These conjectures, if (or when) they hold, are damaging for quantum error-correction as required by fault-tolerant quantum…

Quantum Physics · Physics 2008-06-17 Gil Kalai

Large-scale quantum systems require optical coherence between distant quantum devices, necessitating spectral indistinguishability. Scalable solid-state platforms offer promising routes to this goal. However, environmental disorders,…

Decoherence in Markovian systems can result indirectly from the action of a system Hamiltonian which is usually fixed and unavoidable. Here, we show that in general in Markovian systems, because of the system Hamiltonian, quantum…

Quantum Physics · Physics 2008-08-13 Manas K. Patra , Peter G. Brooke

Three different levels of noisy quantum schemes modeling are considered: vectors, density matrices and Choi-Jamiolkowski related states. The implementations for personal computers and supercomputers are described, and the corresponding…

A generalized formal framework for decoherence, that can be used both in open and closed quantum systems, is sketched. In this context, the relationship between the decoherence of a closed system and the decoherence of its subsystems is…

Quantum Physics · Physics 2007-05-23 Mario Castagnino , Roberto Laura , Olimpia Lombardi

Quantum decoherence has been studied using nuclear magnetic resonance(NMR). By choosing one qubit to simulate environment, we examine the decoherence behavior of two quantum systems: a one qubit system and a two qubit system. The…

Quantum Physics · Physics 2007-05-23 Jingfu Zhang , Zhiheng Lu , Lu Shan , Zhiwei Deng

We study dynamics of quantum open systems, paying special attention to those aspects of their evolution which are relevant to the transition from quantum to classical. We begin with a discussion of the conditional dynamics of simple…

Quantum Physics · Physics 2015-06-26 Juan Pablo Paz , Wojciech Hubert Zurek

We consider the process of changing reference frames in the case where the reference frames are quantum systems. We find that, as part of this process, decoherence is necessarily induced on any quantum system described relative to these…

Quantum Physics · Physics 2014-05-23 Matthew C. Palmer , Florian Girelli , Stephen D. Bartlett

For a wide set of quantum systems it is demonstrated that the quantum regime can be considered as the transient phase while the final classical statistical regime is a permanent state. A basis where exact matrix decoherence appears for…

Quantum Physics · Physics 2009-11-06 Mario Castagnino , Roberto Laura

I study the scaling behavior in the physical parameters of dynamical entropies, classical and quantum, in a specifically devised model of collision-induced decoherence in a chaotic system. The treatment is fully canonical and no…

Quantum Physics · Physics 2024-07-17 Giorgio Mantica

Quantum feedback is assuming increasingly important role in quantum control and quantum information processing. In this work we analyze the application of such feedback techniques in eliminating decoherence in open quantum systems. In order…

Quantum Physics · Physics 2016-11-15 Narayan Ganesan , Tzyh Jong Tarn