Asymptotic Entropy Research Articles

ASYMPTOTIC ENTANGLEMENT IN THE PARAMETRIZED HADAMARD WALK

We study asymptotic entanglement properties of the Hadamard walk with phase parameters on the line using the Fourier representation. We use the von Neumann entropy of the reduced density operator to quantify entanglement between the coin and position degrees of freedom. We investigate obtaining exact expressions for the asymptotic entropy of entanglement, for different classes of initial conditions. We also determine under which conditions the asymptotic entropy of entanglement can be characterized as full, intermediate, or minimum.

The Entropy of a Discrete Real Variable

The discrete Shannon entropy H was formulated only to measure indeterminacy effected through a set of probabilities, but the indeterminacy in a real-valued discrete variable depends on both the allowed outcomes x and the corresponding probabilities Þ. A fundamental measure that is sensitive to both x and p is derived here from the total differential entropy of a continuous real variable and its conjugate in the discrete limit, where the conjugate is universally eliminated. The asymptotic differential entropy recovers H plus the new measure, named ≡, which provides a novel probe of intrinsic organization in sequences of real numbers.

Predictability of operational processes over finite horizon

Operational processes are usually studied in terms of stochastic processes. The main information measure used for predictability of stochastic processes is the entropy rate, which is asymptotic conditional entropy, thus not suitable for application over a finite horizon. We use the conditional entropy to study the predictability of stochastic processes over the finite horizon. It is well-known that the conditional entropies of stationary processes decrease as the processes evolve, implying that, on average, their pasts become more informative about prediction of their future outcomes. Some important operational processes such as martingale, models for maintenance policies, nonhomogeneous Poisson, and mixed Poisson processes are nonstationary. We show that as a nonstationary process evolves, it may provide more information or less information about the future state of the system. We develop results for comparing the predictability of stochastic processes. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011

Invariance entropy for outputs

For continuous time control systems, this paper analyzes output invariance entropy as a measure for the information necessary to achieve invariance of compact subsets of the output space. For linear control systems with compact control range, relations to controllability and observability properties are studied. Furthermore, the notion of asymptotic output invariance entropy is introduced and characterized for these systems.

Transformation properties of entropy production

The transformation properties of entropy production under phase-space partitioning, lumping, or the elimination of intermediate steps and variables in the presence of widely separated time scales are studied. Conditions are derived under which dissipation remains invariant. In systems subjected to external periodic driving the adiabatic, asymptotic, and transient entropy productions are evaluated and the extent to which they can be separately non-negative is determined.

Asymptotic Entropy of Random Walks on Free Products

Suppose we are given the free product $V$ of a finite family of finite or countable sets. We consider a transient random walk on the free product arising naturally from a convex combination of random walks on the free factors. We prove the existence of the asymptotic entropy and present three different, equivalent formulas, which are derived by three different techniques. In particular, we will show that the entropy is the rate of escape with respect to the Greenian metric. Moreover, we link asymptotic entropy with the rate of escape and volume growth resulting in two inequalities.

Homomorphisms to \mathbb{R} constructed from random walks

Nous donnons une construction d’homomorphismes d’un groupe dans les nombres réels en utilisant une marche aléatoire sur le groupe. Cette construction est une alternative à une construction antécédente qui de plus s’applique dans des cas plus généraux. Les applications comprennent une estimation de la vitesse de fuite de marches aléatoires sur des groupes de croissance sous-exponentielle n’admettant pas d’homomorphismes non triviaux dans les nombres entiers et des inégalités entre la vitesse de fuite asymptotique et l’entropie asymptotique. Certaines des estimations d’entropie obtenues ont des applications indépendantes de la construction de l’homomorphisme, comme par exemple un théorème à la Liouville pour les fonctions harmoniques croissant lentement sur les groupes de croissance sous-exponentielle et certains groupes de croissance exponentielle.

Random Walks on Directed Covers of Graphs

Directed covers of finite graphs are also known as periodic trees or trees with finitely many cone types. We expand the existing theory of directed covers of finite graphs to those of infinite graphs. While the lower growth rate still equals the branching number, upper and lower growth rates no longer coincide in general. Furthermore, the behavior of random walks on directed covers of infinite graphs is more subtle. We provide a classification in terms of recurrence and transience and point out that the critical random walk may be recurrent or transient. Our proof is based on the observation that recurrence of the random walk is equivalent to the almost sure extinction of an appropriate branching process. Two examples in random environment are provided: homesick random walk on infinite percolation clusters and random walk in random environment on directed covers. Furthermore, we calculate, under reasonable assumptions, the rate of escape with respect to suitable length functions and prove the existence of the asymptotic entropy providing an explicit formula which is also a new result for directed covers of finite graphs. In particular, the asymptotic entropy of random walks on directed covers of finite graphs is positive if and only if the random walk is transient.

Fluctuation Theorems for Entropy Production and Heat Dissipation in Periodically Driven Markov Chains

Asymptotic fluctuation theorems are statements of a Gallavotti-Cohen symmetry in the rate function of either the time-averaged entropy production or heat dissipation of a process. Such theorems have been proved for various general classes of continuous-time deterministic and stochastic processes, but always under the assumption that the forces driving the system are time independent, and often relying on the existence of a limiting ergodic distribution. In this paper we extend the asymptotic fluctuation theorem for the first time to inhomogeneous continuous-time processes without a stationary distribution, considering specifically a finite state Markov chain driven by periodic transition rates. We find that for both entropy production and heat dissipation, the usual Gallavotti-Cohen symmetry of the rate function is generalized to an analogous relation between the rate functions of the original process and its corresponding backward process, in which the trajectory and the driving protocol have been time-reversed. The effect is that spontaneous positive fluctuations in the long time average of each quantity in the forward process are exponentially more likely than spontaneous negative fluctuations in the backward process, and vice-versa, revealing that the distributions of fluctuations in universes in which time moves forward and backward are related. As an additional result, the asymptotic time-averaged entropy production is obtained as the integral of a periodic entropy production rate that generalizes the constant rate pertaining to homogeneous dynamics.

Percolation of entropy functionals on cayley tree graphs as a method of order-disorder character diagnostics of complex structures

The problem of long-range action identification of classical quartet, honeycomb, and simplex lattices and bihexagonal Duneau-Katz lattice has been solved. The percolation problem is considered in terms of entropy functional on Cayley tree graphs. Long-range order is described not only by hyperbolic percolation entropy dependence with γ ≤ 1 and zero-order asymptotic entropy; the residual entropy of system ordering can also be observed in some cases.

Entanglement theory and the second law of thermodynamics

Entanglement is central both to the foundations of quantum theory and, as a novel resource, to quantum information science. The theory of entanglement establishes basic laws that govern its manipulation, in particular the non-increase of entanglement under local operations on the constituent particles. Such laws aim to draw from them formal analogies to the second law of thermodynamics; however, whereas in the second law the entropy uniquely determines whether a state is adiabatically accessible from another, the manipulation of entanglement under local operations exhibits a fundamental irreversibility, which prevents the existence of such an order. Here, we show that a reversible theory of entanglement and a rigorous relationship with thermodynamics may be established when considering all non-entangling transformations. The role of the entropy in the second law is taken by the asymptotic relative entropy of entanglement in the basic law of entanglement. We show the usefulness of this approach to general resource theories and to quantum information theory.

A relation between dimension of the harmonic measure, entropy and drift for a random walk on a hyperbolic space

We establish in this paper an exact formula which links the dimension of the harmonic measure, the asymptotic entropy and the rate of escape for a random walk on a discrete subgroup of the isometry group of a Gromov hyperbolic space. This completes a result obtained by the author in a previous paper, where only an upper bound for the dimension was proved.

Remarks on the Equivalence of Full Additivity and Monotonicity for the Entanglement Cost

We analyse the relationship between the full additivity of the entanglement cost and its full monotonicity under local operations and classical communication. We show that the two properties are equivalent for the entanglement cost. The proof works for the regularization of any convex, subadditive, and asymptotically continuous entanglement monotone, and hence also applies to the asymptotic relative entropy of entanglement.

Asymptotic entropy and Green speed for random walks on countable groups

We study asymptotic properties of the Green metric associated with transient random walks on countable groups. We prove that the rate of escape of the random walk computed in the Green metric equals its asymptotic entropy. The proof relies on integral representations of both quantities with the extended Martin kernel. In the case of finitely generated groups, where this result is known (Benjamini and Peres [Probab. Theory Related Fields 98 (1994) 91–112]), we give an alternative proof relying on a version of the so-called fundamental inequality (relating the rate of escape, the entropy and the logarithmic volume growth) extended to random walks with unbounded support.

Asymptotic Nusselt and entropy generation numbers for non-Newtonian fluid flow

The first and the second laws of thermodynamics are applied to obtain general expressions for the asymptotic Nusselt (Nu∞) and entropy generation (Ns∞) numbers in ducts of circular cross-section or a channel made of two long parallel plates. The governing momentum and energy equations are simplified with reasonable assumptions and solved to obtain closed form of analytical solutions. Results of the asymptotic Nusselt and Bejan numbers are presented graphically as a function of fluid index (n), Peclet number (Pe), and group parameter (Br/Ω).

Piecewise automatic groups

We introduce a notion of a piecewise automatic group. Among these groups we describe a new class of groups of intermediate growth. We show that for any function f:N→N, there exists a finitely generated torsion group of intermediate growth G for which the Folner function satisfies FolG,S(n)≥f(n) for some generating set S and all sufficiently large n. As a corollary we see that the asymptotic entropy of simple random walks on these groups could be arbitrarily close to being linear, while the Poisson boundary is trivial

"MÜNCHHAUSEN TRICK" AND AMENABILITY OF SELF-SIMILAR GROUPS

The structure of a self-similar group G naturally gives rise to a transformation which assigns to any probability measure μ on G and any vertex w in the action tree of the group a new probability measure μw. If the measure μ is self-similar in the sense that μw is a convex combination of μ and the δ-measure at the group identity, then the asymptotic entropy of the random walk (G, μ) vanishes; therefore, the random walk is Liouville and the group G is amenable. We construct self-similar measures on several classes of self-similar groups, including the Grigorchuk group of intermediate growth.

Asymptotic Nusselt and entropy generation numbers for non-Newtonian fluid flow

The first and the second laws of thermodynamics are applied to obtain general expressions for the asymptotic Nusselt (Nu∞) and entropy generation (Ns∞) numbers in ducts of circular cross-section or a channel made of two long parallel plates. The governing momentum and energy equations are simplified with reasonable assumptions and solved to obtain closed form of analytical solutions. Results of the asymptotic Nusselt and Bejan numbers are presented graphically as a function of fluid index (n), Peclet number (Pe), and group parameter (Br/Ω).

Singularité de la mesure harmonique sur le bord d'un groupe hyperbolique

This Note deals with the dimension of the harmonic measure ν associated with a random walk on the isometry group of a Gromov hyperbolic space. We establish a link of the form dim ν ⩽ h / l between the dimension of the harmonic measure, the asymptotic entropy h of the random walk and its rate of escape l. Then we use this inequality to show that the dimension of this measure can be made arbitrarily small and deduce a result on the type of the harmonic measure. To cite this article: V. Le Prince, C. R. Acad. Sci. Paris, Ser. I 340 (2005).

Quantum dynamics, measurement and entropy

The aim of this paper is to present a line of ideas, centred around entropy production andquantum dynamics, emerging from von Neumann's work on foundations of quantum mechanics and leading to current research. The concepts of measurement, dynamical evolution and entropy were central in J. von Neumann's work. Further developments led to the introduction of generalized measurements in terms of positive operator-valued measures, closely connected to the theory of open systems. Fundamental properties of quantum entropy were derived and Kolmogorov and Sinai related the chaotic properties of classical dynamical systems with asymptotic entropy production. Finally, entropy production in quantum dynamical systems was linked with repeated measurement processes and a whole research area on nonequilibrium phenomena in quantum dynamical systems seems to emerge.