Spin-orbit-coupled quantum memory of a double quantum dot

TL;DR

This paper introduces the concept of spin-orbit quantum memory in bipartite systems with spin-orbit coupling, demonstrating how measurements on the spin part can reduce uncertainty in the orbital part, with effects amplified by stronger coupling.

Contribution

It extends the quantum memory concept to spin-orbit coupled systems and analyzes measurement effects on uncertainty and entanglement in such systems.

Findings

Measurement on spin reduces orbital uncertainty

Spin-orbit coupling enhances measurement effects

POVM measurements are non-invasive in the studied protocol

Abstract

The concept of quantum memory plays an incisive role in the quantum information theory. As confirmed by several recent rigorous mathematical studies, the quantum memory inmate in the bipartite system $\rho_{AB}$ can reduce uncertainty about the part $B$, after measurements done on the part $A$. In the present work, we extend this concept to the systems with a spin-orbit coupling and introduce a notion of spin-orbit quantum memory. We self-consistently explore Uhlmann fidelity, pre and post measurement entanglement entropy and post measurement conditional quantum entropy of the system with spin-orbit coupling and show that measurement performed on the spin subsystem decreases the uncertainty of the orbital part. The uncovered effect enhances with the strength of the spin-orbit coupling. We explored the concept of macroscopic realism introduced by Leggett and Garg and observed that POVM measurements done on the system under the particular protocol are non-noninvasive. For the extended system, we performed the quantum Monte Carlo calculations and explored reshuffling of the electron densities due to the external electric field.