An Upper Bound on Quantum Entropy (original) (raw)

A classical bound on quantum entropy A classical bound on quantum entropy

A classical upper bound for quantum entropy is identified and illustrated, 0 S q ln(eσ 2 /2h), involving the variance σ 2 in phase space of the classical limit distribution of a given system. A fortiori, this further bounds the corresponding information-theoretical generalizations of the quantum entropy proposed by Rényi.

On upper bound for the quantum entropy

Linear Algebra and its Applications, 2001

A new upper bound for the von Neumann entropy of a state of a compound quantum system is given. This leads to a log-Sobolev inequality on the matrix algebra.

Information entropy and bound quantum states

Physical Review A, 2009

We explore a few advantages of studying the change in information entropy of a bound quantum state with energy. It is known that the property generally increases with the quantum number for stationary states, in spite of the concomitant gradual increase in the number of constraints for higher levels. A simple semiclassical proof of this observation is presented via the Wilson-Sommerfeld quantization scheme. In the small quantum number regime, we numerically demonstrate how far the semiclassical predictions are valid for a few systems, some of which are exactly solvable and some not so. Our findings appear to be significant in a number of ways. We observe that, for most problems, information entropy tends to a maximum as the quantum number tends to infinity. This sheds some light on the Bohr limit as a classical limit. Noting that the dependence of energy on the quantum number governs the rate of increase of information entropy with the degree of excitation, we extend our analysis to include the role of the kinetic energy. The endeavor yields a relation that possesses a universal character for any one-dimensional problem. Relevance of information entropy in studying the goodness of approximate stationary states obtained from finite-basis linear variational calculations is also delineated. Finally, we expound how this property behaves in situations where shape resonances show up. A typical variation is indeed observed in such cases when we proceed to detect Siegert states via the stabilization method.

Quantum Entropy and Complexity

Open Systems & Information Dynamics

We study the relations between the recently proposed machine-independent quantum complexity of P. Gacs [1] and the entropy of classical and quantum systems. On one hand, by restricting Gacs complexity to ergodic classical dynamical systems, we retrieve the equality between the Kolmogorov complexity rate and the Shannon entropy rate derived by A. A. Brudno [2]. On the other hand, using the quantum Shannon-McMillan theorem [3], we show that such an equality holds densely in the case of ergodic quantum spin chains.

Quantum Relative Entropy

2015

Mark M. Wilde, Assistant Professor at Louisiana State University, has improved this theorem in a way that allows for understanding how quantum measurements can be approximately reversed under certain circumstances. The new results allow for understanding how quantum information that has been lost during a measurement can be nearly recovered, which has potential implications for a variety of quantum technologies. [9]

Bounds on general entropy measures

Journal of Physics A: Mathematical and General, 2003

We show how to determine the maximum and minimum possible values of one measure of entropy for a given value of another measure of entropy. These maximum and minimum values are obtained for two standard forms of probability distribution (or quantum state) independent of the entropy measures, provided the entropy measures satisfy a concavity/convexity relation. These results may be applied to entropies for classical probability distributions, entropies of mixed quantum states and measures of entanglement for pure states.

Entropy Bounds: New Insights

Symmetry

In this paper we review the fundamental concepts of entropy bounds put forward by Bousso and its relation to the holographic principle. We relate covariant entropy with logarithmic distance of separation of nearby geodesics. We also give sufficient arguments to show that the origin of entropy bounds is not indeed thermodynamic, but statistical.

Information-theoretical meaning of quantum-dynamical entropy

Physical Review A, 2002

The theory of noncommutative dynamical entropy and quantum symbolic dynamics for quantum dynamical systems is analised from the point of view of quantum information theory. Using a general quantum dynamical system as a communication channel one can define different classical capacities depending on the character of resources applied for encoding and decoding procedures and on the type of information sources. It is shown that for Bernoulli sources the entanglement-assisted classical capacity, which is the largest one, is bounded from above by the quantum dynamical entropy defined in terms of operational partitions of unity. Stronger results are proved for the particular class of quantum dynamical systems-quantum Bernoulli shifts. Different classical capacities are exactly computed and the entanglementassisted one is equal to the dynamical entropy in this case.

On The Information-Theoretical Entropy for Some Quantum Oscillators

Annals of West University of Timisoara - Physics

The information-theoretical entropy, also called the “classical” entropy, was introduced by Wehrl in terms of the Glauber coherent states (CSs) | z > , i.e. the CSs corresponding to the one-dimensional harmonic oscillator (HO-1D). In the present paper, we have focused our attention on the examination of the information-theoretical entropy, i.e. the Wehrl entropy, for both the pure and the mixed (thermal) states of some quantum oscillators.

Statistical entropy of open quantum systems

Physical Review E, 2016

Dissipative quantum systems are frequently described within the framework of the so-called "system-plus-reservoir" approach. In this work we assign their description to the Maximum Entropy Formalism and compare the resulting thermodynamic properties with those of the wellestablished approaches. Due to the non-negligible coupling to the heat reservoir, these systems are non-extensive by nature, and the former task may require the use of non-extensive parameter dependent informational entropies. In doing so, we address the problem of choosing appropriate forms of those entropies in order to describe a consistent thermodynamics for dissipative quantum systems. Nevertheless, even having chosen the most successful and popular forms of those entropies, we have proven our model to be a counterexample where this sort of approach leads us to wrong results. I.