Active Quantum Memory Using Oscillating Dark States

TL;DR

This paper introduces an active quantum memory method using Oscillating Dark States in a three-level atomic system, enabling long-term storage with suppressed decoherence and high fidelity, surpassing passive schemes.

Contribution

The paper presents a novel active quantum memory approach utilizing oscillating dark states to significantly extend storage time and reduce decoherence.

Findings

Achieves long quantum state storage with high fidelity.

Decoherence is greatly suppressed compared to passive schemes.

Storage time can be thousands of times longer than traditional methods.

Abstract

An active method for long time storage of quantum superposition state in atomic system using the Oscillating Dark States (ODS) is presented. Quantum state of a three-level $\Lambda$ configuration atomic system oscillates periodically between two ground levels, when two pairs of classical detuning laser fields driving the system into the ODS under evolving adiabatic conditions. When considering another uploading/unloading adiabatic conditions and applying the oscillation of the ODS to quantum state storage, surprisingly, we can obtain the greatly suppressed decoherence of the system and high fidelity of the retrieved state, even if decay factor of coherence term of the system density matrix $\gamma_{21}$$\cdot$ $t$$ \gg$1. The storage time is not limited by coherence decay time of the atomic system any longer, and can be thousands of times longer than that in those passive schemes without additional laser fields.