Quantum information entropy and squeezing of 𝒫𝒯-symmetric potential

The information theoretic concepts are crucial to study the quantum mechanical systems. In this paper, the information densities of [Formula: see text]-symmetric potential have been demonstrated and their properties deeply analyzed. The position space and momentum space information entropy is obtained and Bialynicki-Birula–Mycielski inequality is saturated for different parameters of the potential. Some interesting features of information entropy have been discussed. The variation in these entropies is described which gets saturated for specific values of the parameter. These have also been analyzed for the [Formula: see text]-symmetry breaking case. Further, the entropy squeezing phenomenon has been investigated in position space as well as momentum space. Interestingly, [Formula: see text] phase transition conjectures the entropy squeezing in position space and momentum space.

Download Full-text

Universality of phase transition dynamics: Topological defects from symmetry breaking

International Journal of Modern Physics A ◽

10.1142/s0217751x1430018x ◽

2014 ◽

Vol 29 (08) ◽

pp. 1430018 ◽

Cited By ~ 146

Author(s):

Adolfo del Campo ◽

Wojciech H. Zurek

Keyword(s):

Phase Transition ◽

Critical Point ◽

Topological Defects ◽

Continuous Phase ◽

Nonequilibrium Dynamics ◽

Quantum Mechanical ◽

Quench Rate ◽

Transition Dynamics ◽

Slowing Down ◽

Quantum Mechanical Systems

In the course of a nonequilibrium continuous phase transition, the dynamics ceases to be adiabatic in the vicinity of the critical point as a result of the critical slowing down (the divergence of the relaxation time in the neighborhood of the critical point). This enforces a local choice of the broken symmetry and can lead to the formation of topological defects. The Kibble–Zurek mechanism (KZM) was developed to describe the associated nonequilibrium dynamics and to estimate the density of defects as a function of the quench rate through the transition. During recent years, several new experiments investigated the formation of defects in phase transitions induced by a quench both in classical and quantum mechanical systems. At the same time, some established results were called into question. We review and analyze the Kibble–Zurek mechanism focusing in particular on this surge of activity, and suggest possible directions for further progress.

Download Full-text

Quantum Information Entropy and Entropy Squeezing of Isospectral Modified Hylleraas Plus Exponential Rosen Morse Potential and Isospectral Eckart Potential

New Physics Sae Mulli ◽

10.3938/npsm.70.778 ◽

2020 ◽

Vol 70 (9) ◽

pp. 778-787

Author(s):

Pooja THAKUR* ◽

Rama GUPTA ◽

Aarti SHARMA ◽

Anil KUMAR

Keyword(s):

Quantum Information ◽

Information Entropy ◽

Morse Potential ◽

Entropy Squeezing ◽

Eckart Potential

Download Full-text

Robust dynamical decoupling

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2011.0355 ◽

2012 ◽

Vol 370 (1976) ◽

pp. 4748-4769 ◽

Cited By ~ 78

Author(s):

Alexandre M. Souza ◽

Gonzalo A. Álvarez ◽

Dieter Suter

Keyword(s):

Quantum Information ◽

Pulse Sequences ◽

Coherence Time ◽

Quantum Mechanical ◽

Quantum Computers ◽

Dynamical Decoupling ◽

Quantum Bits ◽

Quantum Mechanical Systems ◽

Further Development ◽

Loss Of Coherence

Quantum computers, which process information encoded in quantum mechanical systems, hold the potential to solve some of the hardest computational problems. A substantial obstacle for the further development of quantum computers is the fact that the lifetime of quantum information is usually too short to allow practical computation. A promising method for increasing the lifetime, known as dynamical decoupling (DD), consists of applying a periodic series of inversion pulses to the quantum bits. In the present review, we give an overview of this technique and compare different pulse sequences proposed earlier. We show that pulse imperfections, which are always present in experimental implementations, limit the performance of DD. The loss of coherence due to the accumulation of pulse errors can even exceed the perturbation from the environment. This effect can be largely eliminated by a judicious design of pulses and sequences. The corresponding sequences are largely immune to pulse imperfections and provide an increase of the coherence time of the system by several orders of magnitude.

Download Full-text