Coherence preservation of a single neutral atom qubit transferred between magic-intensity optical traps

TL;DR

This paper demonstrates that using a magic-intensity optical trap preserves the coherence of a mobile neutral atom qubit during transfer, significantly extending coherence time and enabling scalable quantum computing architectures.

Contribution

It introduces a novel magic-intensity trapping technique that mitigates light shift decoherence by considering hyperpolarizability, enhancing qubit coherence during transfer.

Findings

Coherence time extended to 225 ms using magic trapping.

Hyperpolarizability causes a parabolic light shift dependence.

First measurement of hyperpolarizability in this context.

Abstract

We demonstrate that the coherence of a single mobile atomic qubit can be well preserved during a transfer process among different optical dipole traps (ODTs). This is a prerequisite step in realizing a large-scale neutral atom quantum information processing platform. A qubit encoded in the hyperfine manifold of $^{87}$Rb atom is dynamically extracted from the static quantum register by an auxiliary moving ODT and reinserted into the static ODT. Previous experiments were limited by decoherences induced by the differential light shifts of qubit states. Here we apply a magic-intensity trapping technique which mitigates the detrimental effects of light shifts and substantially enhances the coherence time to $225 \pm 21\,\mathrm{ms}$. The experimentally demonstrated magic trapping technique relies on the previously neglected hyperpolarizability contribution to the light shifts, which makes the light shift dependence on the trapping laser intensity to be parabolic. Because of the parabolic dependence, at a certain "magic" intensity, the first order sensitivity to trapping light intensity variations over ODT volume is eliminated. We experimentally demonstrate the utility of this approach and measure hyperpolarizability for the first time. Our results pave the way for constructing a scalable quantum-computing architectures with single atoms trapped in an array of magic ODTs.