Qubit Gate Operations in Elliptically Trapped Polariton Condensates

TL;DR

This paper proposes a method for implementing universal single- and two-qubit gates using exciton-polariton condensates in elliptical traps, enabling optical control of qubits for quantum computing applications.

Contribution

It introduces a novel approach to realize qubits and quantum gates in polariton condensates confined in elliptical traps, including analysis of gate fidelity under realistic error sources.

Findings

Single-qubit gates achieved via optical tuning of Bloch vector.

Two-qubit gates such as CPHASE, iSWAP, CNOT demonstrated.

Gate fidelities affected by dephasing and relaxation mechanisms.

Abstract

We consider bosonic condensates of exciton-polaritons optically confined in elliptical traps. A superposition of two non-degenerated \textit{p}-type states of the condensate oriented along the two main axes of the trap is represented by a point on a Bloch sphere, being considered as an optically tunable qubit. We describe a set of universal single-qubit gates resulting in a controllable shift of the Bloch vector by means of an auxiliary laser beam. Moreover, we consider interaction mechanisms between two neighboring traps that enable designing two-qubit operations such as CPHASE, \textit{i}SWAP, and CNOT gates. Both the single- and two-qubit gates are analyzed in the presence of error sources in the context of polariton traps, such as pure dephasing and spontaneous relaxation mechanisms, leading to a fidelity reduction of the final qubit states and quantum concurrence, as well as the increase of Von Neumann entropy. We also discuss the applicability of our qubit proposal in the context of DiVincenzo's criteria for the realization of local quantum computing processes. Altogether, the developed set of quantum operations would pave the way to the realization of a variety of quantum algorithms in a planar microcavity with a set of optically induced elliptical traps.