Controlling Spin Qubits in Quantum Dots

TL;DR

This paper reviews progress in using electron spins in quantum dots for quantum computing, including experimental measurements, decoherence analysis, spin filtering, readout schemes, and potential applications.

Contribution

It provides a comprehensive overview of experimental and theoretical advances in spin qubits in quantum dots, highlighting new measurement techniques and applications.

Findings

Long spin relaxation times (~ms) observed in experiments

Theoretically predicted long decoherence times due to spin-orbit interaction

Successful demonstration of spin filtering and high-precision readout schemes

Abstract

We review progress on the spintronics proposal for quantum computing where the quantum bits (qubits) are implemented with electron spins. We calculate the exchange interaction of coupled quantum dots and present experiments, where the exchange coupling is measured via transport. Then, experiments on single spins on dots are described, where long spin relaxation times, on the order of a millisecond, are observed. We consider spin-orbit interaction as sources of spin decoherence and find theoretically that also long decoherence times are expected. Further, we describe the concept of spin filtering using quantum dots and show data of successful experiments. We also show an implementation of a read out scheme for spin qubits and define how qubits can be measured with high precision. Then, we propose new experiments, where the spin decoherence time and the Rabi oscillations of single electrons can be measured via charge transport through quantum dots. Finally, all these achievements have promising applications both in conventional and quantum information processing.