Qubit Analog with Polariton Superfluid in an Annular Trap

TL;DR

This paper demonstrates a polariton-based qubit analog using superfluid vortex states in an annular trap, showing coherent control and potential for quantum computation applications.

Contribution

It introduces a novel polariton qubit system with controllable superfluid vortex states and provides a theoretical model matching experimental results.

Findings

Observation of coherent oscillations between vortex states

Tunable coupling and energy levels of the qubit states

Potential for implementing quantum gates with polaritonic qubits

Abstract

We report on the experimental realization and characterization of a qubit analog with semiconductor exciton-polaritons. In our system, a condensate of exciton-polaritons is confined by a spatially-patterned pump laser in an annular trap that supports energy-degenerate circulating currents of the polariton superfluid. Using temporal interference measurements, we observe coherent oscillations between a pair of counter-circulating superfluid vortex states of the polaritons coupled by elastic scattering off the laser-imprinted potential. The qubit basis states correspond to the symmetric and antisymmetric superpositions of the two vortex states forming orthogonal double-lobe spatial wavefunctions. By engineering the potential, we tune the coupling and coherent oscillations between the two circulating current states, control the energies of the qubit basis states, and initialize the qubit in the desired state. The dynamics of the system is accurately reproduced by our theoretical two-state model, and we discuss potential avenues to achieve complete control over our polaritonic qubits and realize controllable interactions between such qubits to implement quantum gates and algorithms analogous to quantum computation with standard qubits.