Faithful state transfer between two-level systems via an actively cooled finite-temperature cavity

TL;DR

This paper demonstrates a method for high-fidelity quantum state transfer between two Rydberg atom qubits via a finite-temperature microwave cavity, utilizing quantum interference and active cavity cooling to mitigate thermal photon effects.

Contribution

It introduces a protocol for effective state transfer in thermal environments by exploiting quantum interference and active cavity cooling, addressing thermal photon challenges.

Findings

Quantum interference enables robust state transfer at large detuning.

Active cavity cooling maintains high fidelity despite thermal photons.

Differential Stark shifts hinder transfer when coupling strengths differ.

Abstract

We consider state transfer between two qubits - effective two-level systems represented by Rydberg atoms - via a common mode of a microwave cavity at finite temperature. We find that when both qubits have the same coupling strength to the cavity field, at large enough detuning from the cavity mode frequency, quantum interference between the transition paths makes the swap of the excitation between the qubits largely insensitive to the number of thermal photons in the cavity. When, however, the coupling strengths are different, the photon number-dependent differential Stark shift of the transition frequencies precludes efficient transfer. Nevertheless, using an auxiliary cooling system to continuously extract the cavity photons, we can still achieve a high-fidelity state transfer between the qubits.