Multispin errors in the optical control of a spin quantum lattice

Abstract

We study a spin lattice realized with an array of charged quantum dots and embedded in a cavity. Optically excited polaritons, i.e., exciton-cavity-mixed states, interact with the electron spins in the dots. Linearly polarized excitation induces two-spin and multispin interactions. We discuss how the multispin interaction terms, which represent a source of error for two-qubit quantum gates, can be suppressed using local control of the exciton energy. The exciton spontaneous emission and the photon leakage out of the cavity are taken into account. We show that using detuning conditional phase-shift gates with high fidelity can be obtained. The cavity provides long-range spin coupling and the resulting gate operation time is shorter than the spin decoherence time.