scholarly journals Canonical structure of A and B maps

Quanta ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 34-41
Author(s):  
Sudha Sudha ◽  
B. N. Karthik ◽  
A. R. Usha Devi ◽  
A. K. Rajagopal
Keyword(s):  
Quantum System ◽  
Open Quantum System ◽  
Quantum Systems ◽  
The Novel ◽  
Canonical Structure ◽  
Completely Positive ◽  
Open Quantum ◽  
Finite Dimensional ◽  
Positive Nature

In their seminal 1961 paper, Sudarshan, Mathews and Rau investigated properties of the dynamical A and B maps acting on n-dimensional quantum systems. The nature of dynamical maps in open quantum system evolutions has attracted great deal of attention in the later years. However, the novel paper on the A and B dynamical maps has not received its due attention. In this tutorial article, we review the properties of A and B forms associated with the dynamics of finite dimensional quantum systems. In particular, we investigate a canonical structure associated with the A form and establish its equivalence with the associated B form. We show that the canonical structure of the A form captures the completely positive (not completely positive) nature of the dynamics in a succinct manner. This feature is illustrated through physical examples of qubit channels.Quanta 2021; 10: 34–41.

Lyapunov control on quantum systems

2014 ◽  
Vol 28 (30) ◽  
pp. 1430020 ◽  
Author(s):  
L. C. Wang ◽  
X. X. Yi
Keyword(s):  
Quantum System ◽  
Open Quantum System ◽  
Open Quantum Systems ◽  
Logic Gates ◽  
Quantum Systems ◽  
Open Quantum ◽  
Quantum Operations ◽  
Lyapunov Control ◽  
Decoherence Free Subspace ◽  
General Method

We review the scheme of quantum Lyapunov control and its applications into quantum systems. After a brief review on the general method of quantum Lyapunov control in closed and open quantum systems, we apply it into controlling quantum states and quantum operations. The control of a spin-1/2 quantum system, driving an open quantum system into its decoherence free subspace (DFS), constructing single qubit and two-qubit logic gates are taken to illustrate the scheme. The optimalization of the Lyapunov control is also reviewed in this article.

scholarly journals Memory Effects in Quantum Dynamics Modelled by Quantum Renewal Processes

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 905
Author(s):  
Nina Megier ◽  
Manuel Ponzi ◽  
Andrea Smirne ◽  
Bassano Vacchini
Keyword(s):  
Quantum Dynamics ◽  
Open Quantum System ◽  
Open Quantum Systems ◽  
Phenomenological Approach ◽  
Quantum Systems ◽  
Renewal Processes ◽  
Continuous Part ◽  
Trace Distance ◽  
Open Quantum ◽  
And Control

Simple, controllable models play an important role in learning how to manipulate and control quantum resources. We focus here on quantum non-Markovianity and model the evolution of open quantum systems by quantum renewal processes. This class of quantum dynamics provides us with a phenomenological approach to characterise dynamics with a variety of non-Markovian behaviours, here described in terms of the trace distance between two reduced states. By adopting a trajectory picture for the open quantum system evolution, we analyse how non-Markovianity is influenced by the constituents defining the quantum renewal process, namely the time-continuous part of the dynamics, the type of jumps and the waiting time distributions. We focus not only on the mere value of the non-Markovianity measure, but also on how different features of the trace distance evolution are altered, including times and number of revivals.

scholarly journals Experimental test of exchange fluctuation relations in an open quantum system

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
S. Hernández-Gómez ◽  
S. Gherardini ◽  
F. Poggiali ◽  
F. S. Cataliotti ◽  
A. Trombettoni ◽  
...  
Keyword(s):  
Quantum System ◽  
Experimental Test ◽  
Open Quantum System ◽  
Open Quantum ◽  
Fluctuation Relations

Open quantum system parameters for light harvesting complexes from molecular dynamics

2015 ◽  
Vol 17 (38) ◽  
pp. 25629-25641 ◽  
Author(s):  
Xiaoqing Wang ◽  
Gerhard Ritschel ◽  
Sebastian Wüster ◽  
Alexander Eisfeld
Keyword(s):  
Molecular Dynamics ◽  
Quantum System ◽  
Open Quantum System ◽  
Light Harvesting ◽  
Parameter Extraction ◽  
Extraction Methods ◽  
Light Harvesting Complexes ◽  
System Parameters ◽  
Open Quantum ◽  
The Difference

We elucidate the difference between various parameter extraction methods and demonstrate sensitivity to molecular dynamics equilibration.

scholarly journals Experimental realization of high-fidelity teleportation via a non-Markovian open quantum system

2020 ◽  
Vol 102 (6) ◽  
Author(s):  
Zhao-Di Liu ◽  
Yong-Nan Sun ◽  
Bi-Heng Liu ◽  
Chuan-Feng Li ◽  
Guang-Can Guo ◽  
...  
Keyword(s):  
Quantum System ◽  
Open Quantum System ◽  
High Fidelity ◽  
Experimental Realization ◽  
Open Quantum

Non-Markovianity leading to coherence revivals in an open quantum system

2020 ◽  
pp. 2050040
Author(s):  
Y. Yugra ◽  
F. De Zela
Keyword(s):  
Quantum Information ◽  
Quantum System ◽  
Open Quantum System ◽  
Open Systems ◽  
Quantum Correlations ◽  
Experimental Proof ◽  
Optical Setup ◽  
Open Quantum ◽  
All Optical ◽  
Proof Of Principle

Coherence and quantum correlations have been identified as fundamental resources for quantum information tasks. As recently shown, these resources can be interconverted. In multipartite systems, entanglement represents a prominent case among quantum correlations, one which can be activated from coherence. All this makes coherence a key resource for securing the operational advantage of quantum technologies. When dealing with open systems, decoherence hinders full exploitation of quantum resources. Here, we present a protocol that allows reaching the maximal achievable amount of coherence in an open quantum system. By implementing our protocol, or suitable variants of it, coherence losses might be fully compensated, thereby leading to coherence revivals. We provide an experimental proof of principle of our protocol through its implementation with an all-optical setup.

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