Real-time dynamics in diluted quantum networks

by Erik Aurell (KTH)

Thursday 8 Dec 2022, 13:00 → 15:00 Europe/Stockholm

AlbaNova C4:3059 - Café Planck (AlbaNova Main Building)

I will introduce an approach to characterize the dynamics of disordered quantum networks. Each quantum element (i.e., each node) of the network experiences the other nodes as an effective environment that can be self-consistently represented by a Feynman-Vernon influence functional. For networks having the topology of locally treelike graphs, these Feynman-Vernon (FV) functionals can be determined by a new version of the cavity or belief propagation (BP) method. I show how to obtain the fixed point solution of this version of BP for a network of uniform quantum harmonic oscillators. I will also estimate the effects of the disorder in these networks within the replica symmetry ansatz. Over a large time interval, at small disorder, the real part of the FV functional induces decoherence and classicality while at sufficiently large disorder the Feynman-Vernon functional tends to zero and the coherence survives, signaling in a time setting, the onset of an Anderson transition.

This is joint work with Roberto Mulet and Jan Tuziemski, published as Physical Review A vol 105, pp 022205 (2022) .