Time-Reversal-Symmetric Single-Photon Wave Packets for Free-Space Quantum Communication

TL;DR

This paper proposes a method for efficient quantum state transfer between matter and photonic qubits using time-reversal-symmetric single-photon wave packets, avoiding cavities or fibers, suitable for free-space quantum communication.

Contribution

It introduces a cavity-free, high-fidelity quantum state transfer technique utilizing controlled spontaneous emission and absorption with time-reversal symmetry.

Findings

High-fidelity matter-photon state transfer demonstrated

Cavity-free approach simplifies free-space quantum communication

Potential for scalable free-space quantum networks

Abstract

Readout and retrieval processes are proposed for efficient, high-fidelity quantum state transfer between a matter qubit, encoded in the level structure of a single atom or ion, and a photonic qubit, encoded in a time-reversal-symmetric single-photon wave packet. They are based on controlling spontaneous photon emission and absorption of a matter qubit on demand in free space by stimulated Raman adiabatic passage. As these processes do not involve mode selection by high-finesse cavities or photon transport through optical fibers, they offer interesting perspectives as basic building blocks for free-space quantum-communication protocols.