Measurement, control, and decay of quantum-dot spins

TL;DR

This review discusses methods for measuring and controlling quantum-dot spins, focusing on Bell-state measurements, decoherence sources, and their implications for quantum computing viability.

Contribution

It provides a comprehensive overview of measurement techniques, decoherence mechanisms, and experimental decay times relevant to quantum-dot spin-based quantum computing.

Findings

Partial Bell-state measurement proposals enable quantum computing.

Decoherence sources like spin-orbit and hyperfine interactions limit coherence times.

Experimental decay times inform the feasibility of quantum-dot spin quantum computers.

Abstract

In this review we discuss a recent proposal to perform partial Bell-state (parity) measurements on two-electron spin states for electrons confined to quantum dots. The realization of this proposal would allow for a physical implementation of measurement-based quantum computing. In addition, we consider the primary sources of energy relaxation and decoherence which provide the ultimate limit to all proposals for quantum information processing using electron spins in quantum dots. We give an account of the Hamiltonians used for the most important interactions (spin-orbit and hyperfine) and survey some of the recent work done to understand dynamics, control, and decoherence under the action of these Hamiltonians. We conclude the review with a table of important decay times found in experiment, and relate these time scales to the potential viability of measurement-based quantum computing.