Universal quantum gates on electron-spin qubits with quantum dots inside single-side optical microcavities

TL;DR

This paper proposes compact, deterministic quantum gates for electron-spin qubits in quantum dots within optical microcavities, utilizing giant Faraday rotation, with advantages in success probability, simplicity, and experimental feasibility.

Contribution

It introduces new schemes for universal quantum gates that are simple, efficient, and work in various coupling regimes without needing extra qubits.

Findings

Gates achieve 100% success probability in principle.

Schemes are simple, economical, and require only single photons.

Devices are feasible in both weak and strong coupling regimes.

Abstract

We present some compact quantum circuits for a deterministic quantum computing on electron-spin qubits assisted by quantum dots inside single-side optical microcavities, including the CNOT, Toffoli, and Fredkin gates. They are constructed by exploiting the giant optical Faraday rotation induced by a single-electron spin in a quantum dot inside a single-side optical microcavity as a result of cavity quantum electrodynamics. Our universal quantum gates have some advantages. First, all the gates are accomplished with a success probability of 100% in principle. Second, our schemes require no additional electron-spin qubits and they are achieved by some input-output processes of a single photon. Third, our circuits for these gates are simple and economic. Moreover, our devices for these gates work in both the weak coupling and the strong coupling regimes, and they are feasible in experiment.