10 research outputs found
Universal current fluctuations in the symmetric exclusion process and other diffusive systems
We show, using the macroscopic fluctuation theory of Bertini, De Sole,
Gabrielli, Jona-Lasinio, and Landim, that the statistics of the current of the
symmetric simple exclusion process (SSEP) connected to two reservoirs are the
same on an arbitrary large finite domain in dimension as in the one
dimensional case. Numerical results on squares support this claim while results
on cubes exhibit some discrepancy. We argue that the results of the macroscopic
fluctuation theory should be recovered by increasing the size of the contacts.
The generalization to other diffusive systems is straightforward.Comment: 6 pages, 4 figure
Universal entanglement entropy in the ground state of biased bipartite systems
The ground state entanglement entropy is studied in a many-body bipartite
quantum system with either a single or multiple conserved quantities. It is
shown that the entanglement entropy exhibits a universal power-law behaviour at
large -- the occupancy ratio between the two subsystems. Single and
multiple conserved quantities lead to different power-law exponents, suggesting
the entanglement entropy can serve to detect hidden conserved quantities.
Moreover, occupancy measurements allow to infer the bipartite entanglement
entropy. All the above results are generalized for the R\'enyi entropy
Diffusion and entanglement in open quantum systems
The macroscopic fluctuation theory provides a complete hydrodynamic description of nonequilibrium classical diffusive systems. As a first step towards a diffusive theory of open quantum systems, we propose a microscopic open quantum system model —the selective dephasing model. It exhibits genuine quantum diffusive scaling. Namely, the dynamics is diffusive and the density matrix remains entangled at large length scales and long time scales
Universality in dynamical phase transitions of diffusive systems
International audienceUniversality, where microscopic details become irrelevant, takes place in thermodynamic phase transitions. The universality is captured by a singular scaling function of the thermodynamic variables, where the scaling exponents are determined by symmetries and dimensionality only. Universality can persist even for nonequilibrium phase transitions. It implies that a hydrodynamic approach can capture the singular universal scaling function, even far from equilibrium. In particular, we show these results for phase transitions in the large deviation function of the current in diffusive systems with particle-hole symmetry. For such systems, we find the scaling exponents of the universal function and show they are independent of microscopic details as well as boundary conditions