Journal Club

Seminar Room

Tuesday 26th of April, 2022

Hour: 10:00

Title: Entanglement production in the dynamical Casimir effect at parametric resonance

Presented by: Javier Olmedo Nieto

Ref: https://arxiv.org/abs/1908.00835v1

Abstract:

The particles produced from the vacuum in the dynamical Casimir effect are highly entangled. In order to quantify the correlations generated by the process of vacuum decay induced by moving mirrors, we study the entanglement evolution in the dynamical Casimir effect by computing the time-dependent Rényi and von Neumann entanglement entropy analytically in arbitrary dimensions. We consider the system at parametric resonance, where the effect is enhanced. We find that, in (1+1) dimensions, the entropies grow logarithmically for large times, S_A(tau)~log(tau)/2 while in higher dimensions (n+1) the growth is linear, S_A(t)~ lambda tau where lambda can be identified with the Lyapunov exponent of a classical instability in the system. In (1+1) dimensions, strong interactions among field modes prevent the parametric resonance from manifesting as a Lyapunov instability, leading to a sublinear entropy growth associated with a constant rate of particle production in the resonant mode. Interestingly, the logarithmic growth comes with a pre-factor with 1/2 which cannot occur in time-periodic systems with finitely many degrees of freedom and is thus a special property of bosonic field theories.

Hour: 10:00

Title: Helicity and spin conservation in linearized gravity

Presented by: Antonio Manso

Ref: https://doi.org/10.1007/s10714-021-02871-7

Abstract:

The duality-symmetric, Maxwell-like, formulation of linearized gravity introduced by Barnett (New J Phys 16, 2014) is used to generalize the conservation laws for helicity, the spin part of angular momentum, and spin-flux, to the case of linearized gravity. These conservation laws have been shown to follow from the conservation property of the helicity array, an analog of Lipkin’s zilch tensor. The analog of the helicity array for linearized gravity is constructed and is shown to be conserved.