Qubit protection in nuclear-spin quantum dot memories

TL;DR

This paper introduces a method to safeguard quantum information in nuclear-spin quantum dot memories by creating an energy gap via off-resonant hyperfine interactions, protecting against certain noise types.

Contribution

The authors propose a novel energy gap mechanism using off-resonant hyperfine coupling to enhance quantum memory robustness in semiconductor quantum dots.

Findings

Energy gap effectively suppresses local spin-flip noise.

Protection persists despite imperfect initial polarization.

Inhomogeneous hyperfine coupling effects are analyzed.

Abstract

We present a mechanism to protect quantum information stored in an ensemble of nuclear spins in a semiconductor quantum dot. When the dot is charged the nuclei interact with the spin of the excess electron through the hyperfine coupling. If this coupling is made off-resonant it leads to an energy gap between the collective storage states and all other states. We show that the energy gap protects the quantum memory from local spin-flip and spin-dephasing noise. Effects of non-perfect initial spin polarization and inhomogeneous hyperfine coupling are discussed.