Quantum beats of a macroscopic polariton condensate in real space

TL;DR

This study demonstrates quantum beat oscillations in a macroscopic polariton condensate confined in an elliptical trap, revealing controllable quantum superpositions with potential for quantum information applications.

Contribution

The paper reports the first experimental observation and control of quantum beats in a polariton condensate, with visualization of wave function dynamics and implications for qubit coherence.

Findings

Harmonic oscillations observed in polariton condensate due to trap ellipticity

Controlled quantum beats achieved via targeted laser pulses

Predicted qubit coherence time exceeds polariton lifetime by over two orders of magnitude

Abstract

We experimentally observe harmonic oscillations in a bosonic condensate of exciton-polaritons confined within an elliptical trap. These oscillations arise from quantum beats between two size-quantized states of the condensate, split in energy due to the trap's ellipticity. By precisely targeting specific spots inside the trap with nonresonant laser pulses, we control frequency, amplitude, and phase of these quantum beats. The condensate wave function dynamics is visualized on a streak camera and mapped to the Bloch sphere, demonstrating Hadamard and Pauli-Z operations. We conclude that a qubit based on a superposition of these two polariton states would exhibit a coherence time exceeding the lifetime of an individual exciton-polariton by at least two orders of magnitude.