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The conditional shift in the evolution operator of a quantum walk generates entanglement between the coin and position degrees of freedom. This entanglement can be quantified by the von Neumann entropy of the reduced density operator…

Quantum Physics · Physics 2009-11-11 G. Abal , R. Siri , A. Romanelli , R. Donangelo

Entropy, and its temporal evolution, play a central role in the foundations of quantum theory and in modern quantum technologies. Here we study, in particular, the relations between the --- in general, non-Markovian --- evolution of an open…

Quantum Physics · Physics 2018-09-18 Paolo Aniello , Joonwoo Bae , Dariusz Chruscinski

We know that space and time are treated almost equally in classical physics, but we also know that this is not the case for quantum mechanics. A quantum description of both space and time is important to really understand the quantum nature…

Quantum Physics · Physics 2024-02-20 Ngo Phuc Duc Loc

Closed quantum systems follow a unitary time evolution that can be simulated on quantum computers. By incorporating non-unitary effects via, e.g., measurements on ancilla qubits, these algorithms can be extended to open-system dynamics,…

Quantum Physics · Physics 2025-05-07 Peter J. Eder , Jernej Rudi Finžgar , Sarah Braun , Christian B. Mendl

The origin and nature of time in complex systems is explored using quantum (or 'Feynman') clocks and the signals produced by them. Networks of these clocks provide the basis for the evolution of complex systems. The general concept of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Scott Hitchcock

World-wide efforts aim at the realization of advanced quantum simulators and processors. However, despite the development of intricate hardware and pulse control systems, it may still not be generally known which effective quantum dynamics,…

Currently, 'time' does not play any essential role in quantum information theory. In this sense, quantum information theory is underdeveloped similarly to how quantum physics was underdeveloped before Erwin Schrodinger introduced his famous…

Mesoscale and Nanoscale Physics · Physics 2019-09-04 Mohammad H. Ansari , Alwin van Steensel , Yuli V. Nazarov

Quantum random walks are shown to have non-intuitive dynamics which makes them an attractive area of study for devising quantum algorithms for long-standing open problems as well as those arising in the field of quantum computing. In the…

Quantum Physics · Physics 2009-11-13 K. Manouchehri , J. B. Wang

In the above mentioned paper by J. Dunkel and S. A. Trigger [Phys. Rev. {\bf A 71}, 052102, (2005)] a hypothesis has been pursued that the loss of information associated with the quantum evolution of pure states, quantified in terms of an…

Quantum Physics · Physics 2009-11-11 Piotr Garbaczewski

We study the time evolution of entanglement in a quantum version of the Kac ring. Our model consists of two spin chains and quantum gates instead of the classical markers. The gates take one qubit from each ring at a time as an input and…

Statistical Mechanics · Physics 2014-12-15 Johannes M. Oberreuter , Ingo Homrighausen , Stefan Kehrein

We consider a time-dependent small quantum system weakly coupled to an environnement, whose effective dynamics we address by means of a Lindblad equation. We assume the Hamiltonian part of the Lindbladian is slowly varying in time and the…

Mathematical Physics · Physics 2022-02-16 Alain Joye

The Lindblad quantum master equation is one of the central approaches to the physics of open quantum systems. In particular, boundary driving enables the study of transport, where a steady state emerges in the long-time limit, which…

Statistical Mechanics · Physics 2025-02-20 Markus Kraft , Mariel Kempa , Jiaozi Wang , Robin Steinigeweg

Properties of unitary time evolution of quantum systems can be applied to define quantum cryptographic protocols. Dynamics of a qubit can be exploited as a data encryption/decryption procedure by means of timed measurements, implementation…

General Physics · Physics 2017-01-17 Davide Pastorello

This tutorial article showcases the many varieties and uses of quantum walks. Discrete time quantum walks are introduced as counterparts of classical random walks. The emphasis is on the connections and differences between the two types of…

Quantum Physics · Physics 2013-05-16 Daniel Reitzner , Daniel Nagaj , Vladimir Buzek

By using relative entropy of coherence, we characterize the coherence gain induced by some quantum evolutions, including the cohering power of unitary operations and the decohering power of quantum operations. We find that the cohering…

Quantum Physics · Physics 2016-07-28 Zhengjun Xi , Mingliang Hu , Yongming Li , Heng Fan

The time dependent entropy (or Leipnik's entropy) of harmonic and damped harmonic oscillators is extensively investigated by using time dependent wave function obtained by the Feynman path integral method. Our results for simple harmonic…

Quantum Physics · Physics 2012-12-24 O. Ozcan , E. Akturk , R. Sever

We consider discrete and continuous representations of a thermodynamic process in which a random walker (e.g. a molecular motor on a molecular track) uses a periodically pumped energy (work) to pass $N$ sites and move energetically downhill…

Statistical Mechanics · Physics 2023-08-17 Henning Kirchberg , Abraham Nitzan

We study the entanglement dynamics of discrete time quantum walks acting on bounded finite sized graphs. We demonstrate that, depending on system parameters, the dynamics may be monotonic, oscillatory but highly regular, or quasi-periodic.…

Quantum Physics · Physics 2012-03-07 Peter P. Rohde , Alessandro Fedrizzi , Timothy C. Ralph

The mixing process of discrete-time quantum walks on one-dimensional lattices is revisited in a setting where the walker is coupled to an environment, and the time evolution of the walker and the environment is unitary. The mixing process…

Quantum Physics · Physics 2014-07-10 Lauri Lehman

We experimentally realize a quantum clock by using a charge sensor to count charges tunneling through a double quantum dot (DQD). Individual tunneling events are used as the clock's ticks. We quantify the clock's precision while measuring…