Latest Papers in Condensed Matter Physics

Statistical Mechanics

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Entanglement entropy and Wilson loop (1808.09976v2)

Bom Soo Kim

2018-08-29

We study both entanglement and the R'enyi entropies for the 2 dimensional massless Dirac fermions in the presence of topological Wilson loops, which are qualitatively different from those with a chemical potential and a current source. In the language of orbifold theories, the Wilson loop is interpreted as an electric operator while the orbifold twist operator as a magnetic operator. By adapting different normalizations for different topological sectors, we achieve two goals: entanglement entropy can be obtained with a smooth limit from the R'enyi entropy, and the entropies are continuous across the different topological sectors. We provide exact results for the entropies in infinite space, which depend only on the topological Wilson loops parameter, independent of the chemical potential and the current source.

Entropic analysis of the localization-delocalization transition in a one-dimensional correlated lattice (1811.04617v2)

O. Farzadian, T. Oikonomou, M. R. R. Good, M. D. Niry

2018-11-12

In this work, propagation of acoustic waves in a one-dimensional binary chain with different types of correlations in elasticity distribution is studied. We applied entropic analysis to investigate and quantify the localization-delocalization transition in long-range correlated chains in terms of the scaling exponent and discuss its relation to the order-disorder levels in the structure of the chain. The results demonstrated that the entropic consideration detects correctly the critical value of separating localization from delocalization bands.

A Live Maxwell's Demon (1905.09091v2)

Howard J. M. Hanley, Debra J. Searles

2019-05-22

The first direct experimental replication of the Maxwell Demon thought experiment is outlined. The experiment determines the velocity/kinetic energy distribution of the particles in a sample by a novel interpretation of the results from a standard time-of-flight (TOF) small angle neutron scattering (SANS) procedure. Perspex at 293 K was subjected to neutrons at 82.2 K. The key result is a TOF velocity distribution curve that is a direct spatial and time-dependent microscopic probe of the velocity distribution of the Perspex nuclei at 293 K. Having this curve, one can duplicate the Demon's approach by selecting neutrons at known kinetic energies. One example is given: namely, two reservoirs -- hot and cold reservoirs -- were generated from the 293 K source without disturbing its original 293 K energy distribution.

Disordered Kitaev chain with long-range pairing: Loschmidt echo revivals and dynamical phase transitions (1810.06236v2)

Utkarsh Mishra, R. Jafari, Alireza Akbari

2018-10-15

We explore the dynamics of long-range Kitaev chain by varying pairing interaction exponent, . It is well known that distinctive characteristics on the nonequilibrium dynamics of a closed quantum system are closely related to the equilibrium phase transitions. Specifically, the return probability of the system to its initial state (Loschmidt echo), in the finite size system, is expected to exhibit very nice periodicity after a sudden quench to a quantum critical point. Where the periodicity of the revivals scales inversely with the maximum of the group velocity. We show that, contrary to expectations, the periodicity of the return probability breaks for a sudden quench to the non-trivial quantum critical point. Further, We find that, the periodicity of return probability scales inversely with the group velocity at the gap closing point for a quench to the trivial critical point of truly long-range pairing case, . In addition, analyzing the effect of averaging quenched disorder shows that the revivals in the short range pairing cases are more robust against disorder than that of the long rang pairing case. We also study the effect of disorder on the non-analyticities of rate function of the return probability which introduced as a witness of the dynamical phase transition. We exhibit that, the non-analyticities in the rate function of return probability are washed out in the presence of strong disorders.

Gibbs and Boltzmann Entropy in Classical and Quantum Mechanics (1903.11870v2)

Sheldon Goldstein, Joel L. Lebowitz, Roderich Tumulka, Nino Zanghi

2019-03-28

The Gibbs entropy of a macroscopic classical system is a function of a probability distribution over phase space, i.e., of an ensemble. In contrast, the Boltzmann entropy is a function on phase space, and is thus defined for an individual system. Our aim is to discuss and compare these two notions of entropy, along with the associated ensemblist and individualist views of thermal equilibrium. Using the Gibbsian ensembles for the computation of the Gibbs entropy, the two notions yield the same (leading order) values for the entropy of a macroscopic system in thermal equilibrium. The two approaches do not, however, necessarily agree for non-equilibrium systems. For those, we argue that the Boltzmann entropy is the one that corresponds to thermodynamic entropy, in particular in connection with the second law of thermodynamics. Moreover, we describe the quantum analog of the Boltzmann entropy, and we argue that the individualist (Boltzmannian) concept of equilibrium is supported by the recent works on thermalization of closed quantum systems.

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