Universal quantum gates for hybrid systems assisted by quantum dots inside double-sided optical microcavities

TL;DR

This paper proposes deterministic schemes for universal quantum gates between flying photon qubits and stationary electron-spin qubits using quantum dots in double-sided optical microcavities, with high success probability and experimental feasibility.

Contribution

It introduces new schemes for universal quantum gates in hybrid systems that are highly efficient, do not require extra qubits, and work in various coupling regimes.

Findings

Gates achieve 100% success probability in principle

No additional qubits needed for these gates

Feasible in both weak and strong coupling regimes

Abstract

We present some deterministic schemes to construct universal quantum gates, that is, controlled- NOT, three-qubit Toffoli, and Fredkin gates, between flying photon qubits and stationary electron-spin qubits assisted by quantum dots inside double-sided optical microcavities. The control qubit of our gates is encoded on the polarization of the moving single photon and the target qubits are encoded on the confined electron spins in quantum dots inside optical microcavities. Our schemes for these universal quantum gates on a hybrid system have some advantages. First, all the gates are accomplished with the success probability of 100% in principle. Second, our schemes require no additional qubits. Third, the control qubits of the gates are easily manipulated and the target qubits are perfect for storage and processing. Fourth, the gates do not require that the transmission for the uncoupled cavity is balanceable to the reflectance for the coupled cavity, in order to get a high fidelity. Fifth, the devices for the three universal gates work in both the weak coupling and the strong coupling regimes, and they are feasible in experiment.