Latest Research Papers In Condensed Matter Physics | (Cond-Mat.Stat-Mech) 2019-03-12

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Latest Papers in Condensed Matter Physics

Statistical Mechanics

Gauge Theory and Boundary Integrability (1903.03601v1)

Roland Bittleston, David Skinner

2019-03-08

We study the mixed topological / holomorphic Chern-Simons theory of Costello, Witten and Yamazaki on an orbifold , obtaining a description of lattice integrable systems in the presence of a boundary. By performing an order calculation we derive a formula for the the asymptotic behaviour of -matrices associated to rational, quasi-classical -matrices. The -action on fixes a line , and line operators on are shown to be labelled by representations of the twisted Yangian. The OPE of such a line operator with a Wilson line in the bulk is shown to give the coproduct of the twisted Yangian. We give the gauge theory realisation of the Sklyanin determinant and related conditions in the presentation of the boundary Yang-Baxter equation.

Quantum valence bond ice theory for proton-driven quantum spin-dipole liquids (1903.03567v1)

Masahiko G. Yamada, Yasuhiro Tada

2019-03-08

We present a theory of a hybrid quantum liquid state, (QSDL), in a hydrogen-bonded electron system, by combining a quantum proton ice and Anderson's resonating valence bond spin liquid, motivated by the recent experimental discovery of a proton-driven QSDL in -H(Cat-EDT-TTF) (a.k.a. H-Cat). In our theory, an electron spin liquid and a proton dipole liquid are realized simultaneously in the ground state called , while neither of them can be established independently of the other. Analytical and numerical calculations reveal that this state has a volume-law entanglement entropy between spins and dipoles, which is far beyond the (crude) Born-Oppenheimer approximation. We also examine the stability of QSDL with respect to perturbations and discuss implications for experiments in H-Cat and its deuterated analog D-Cat.

Generalized Eigenstate Thermalization in 2d CFTs (1903.03559v1)

Anatoly Dymarsky, Kirill Pavlenko

2019-03-08

Infinite-dimensional conformal symmetry in two dimensions leads to integrability of 2d conformal field theories through an infinite tower of local conserved qKdV charges in involution. We discuss the role this integrable structure plays in equilibration of 2d CFTs. We show that in the thermodynamic limit large central charge 2d CFTs satisfy generalized eigenstate thermalization, with the values of qKdV charges forming a complete set of thermodynamically relevant quantities, which unambiguously determine expectation values of all local observables from the vacuum family. Our work settles the question if non-local or quasi-local charges are necessary to describe equilibrium of large central charge 2d CFTs by showing that upon equilibration local physics can be described by the Generalized Gibbs Ensemble that only includes qKdV charges. In the case of a general initial state, upon equilibration, emerging Generalized Gibbs Ensemble will include negative chemical potentials and holographically will be described by a quasi-classical black hole with quantum soft hair.

Molecular simulations minimally restrained by experimental data (1812.10802v3)

Huafeng Xu

2018-12-27

One popular approach to incorporating experimental data into molecular simulations is to restrain the ensemble average of observables to their experimental values. Here I derive equations for the equilibrium distributions generated by restrained ensemble simulations and the corresponding expected values of observables. My results suggest a method to restrain simulations so that they generate distributions that are minimally perturbed from the unbiased distributions while reproducing the experimental values of the observables within their measurement uncertainties.

Unsupervised identification of the phase transition on the 2D-Ising model (1903.03506v1)

Constantia Alexandrou, Andreas Athenodorou, Charalambos Chrysostomou, Srijit Paul

2019-03-08

We investigate deep learning autoencoders for the unsupervised recognition of phase transitions in physical systems formulated on a lattice. We use spin configurations produced for the 2-dimensional ferromagnetic Ising model in zero external magnetic field. We study numerically the relation between one latent dimension extracted from the autoencoder to the critical temperature . The autoencoder reveals the two phases, one for which the spins are ordered and the other for which spins are disordered, reflecting the restoration of the symmetry as the temperature increases. For the largest volume studied, the transition between the two phases occurs very close to the theoretically extracted critical temperature. We define as a quasi-order parameter the absolute average latent dimension , which enables us to predict the critical temperature. We show that one can build the latent susceptibility and use it to quantify the value of the critical temperature at different lattice sizes and that these values suffer from only small finite scaling effects. We demonstrate that extrapolates to the known theoretical value as suggesting that the autoencoder can also be used to extract the critical temperature of the phase transition to an adequate precision.