The Robustness of a Collectively Encoded Rydberg Qubit

TL;DR

This paper demonstrates a collectively-encoded Rydberg qubit that maintains coherence despite atom loss and electric field noise, highlighting its potential for robust quantum information processing.

Contribution

It introduces a novel collective encoding scheme with Rydberg polaritons that exhibits resilience to atom loss and external perturbations.

Findings

Qubit coherence persists despite atom loss.

Electric field noise dephasing scales as the fourth power of field amplitude.

Coherent read-out achieved via single-photon mapping.

Abstract

We demonstrate a collectively-encoded qubit based on a single Rydberg excitation stored in an ensemble of $N$ entangled atoms. Qubit rotations are performed by applying microwave fields that drive excitations between Rydberg states. Coherent read-out is performed by mapping the excitation into a single photon. Ramsey interferometry is used to probe the coherence of the qubit, and to test the robustness to external perturbations. We show that qubit coherence is preserved even as we lose atoms from the polariton mode, preserving Ramsey fringe visibility. We show that dephasing due to electric field noise scales as the fourth power of field amplitude. These results show that robust quantum information processing can be achieved via collective encoding using Rydberg polaritons, and hence this system could provide an attractive alternative coding strategy for quantum computation and networking.