Doped resonating valence bond states: a quantum information study

Seminar date and time: 
Monday, 12 June, 2017 - 14:30
Affiliation: 
HARISH-CHANDRA RESEARCH INSTITUTE, ALLAHABAD, UTTAR PRADESH, INDIA
Author: 
Sudipto Singha Roy
Location: 
GiQ's seminar room

Abstract:

Resonating valence bond states have played a crucial role in the description of exotic

phases in strongly correlated systems, especially in the realm of Mott insulators and the

associated high­Tc superconducting phase transition. In particular, RVB states are

considered to be an important system to study the ground state properties of the doped

quantum spin­1/2 ladder. It is therefore interesting to understand how quantum correlations

are distributed among the constituents of these composite systems. In this regard, we

formulate an analytical recursive method to generate the wave function of doped short­range

resonating valence bond (RVB) states as a tool to efficiently estimate multisite entanglement

as well as other physical quantities in doped quantum spin ladders. Importantly, our results

show that within a specific doping concentration and model parameter regimes, the doped

RVB state essentially characterizes the trends of genuine multiparty entanglement in the

exact ground states of a Hubbard model with large onsite interactions. Moreover, we

consider an isotropic RVB network of spin­1/2 particles with a finite fraction of defects, where

the corresponding wave function of the network is rotationally invariant under the action of

local unitaries. By using quantum information­theoretic concepts like strong subadditivity of

von Neumann entropy and approximate quantum telecloning, we prove analytically that in

the presence of defects, caused by loss of a finite fraction of spins, the RVB network

sustains genuine multisite entanglement, and at the same time may exhibit finite

moderate­range bipartite entanglement, in contrast to the case with no defects.

Campus d'excel·lència internacional U A B