A coherent and passive one dimensional quantum memory

TL;DR

This paper presents a passive quantum memory mechanism where flying qubits transfer their state to a chain of static spins, enabling reversible encoding and robustness against decoherence, with potential implementation in photonic waveguides with quantum dots.

Contribution

It introduces a passive, reversible quantum memory process for flying qubits using static spin chains, resistant to decoherence and suitable for photonic architectures.

Findings

Quantum state transfer to static spins is passive and coherent.

The process is reversible for multiple qubits.

Memory is robust against spin decoherence and imperfections.

Abstract

We show that the state of a flying qubit may be transferred to a chain of identical, (near) ferromagnetically polarised, but non-interacting, static spin-1/2 particles in a passive way. During this process the flying qubit is coherently polarised, emerging in the direction of the majority static spins. We also show that this process is reversible for at least two flying qubits injected sequentially and thus has the potential to be exploited as a passive quantum memory to encode the flying qubits without the necessity of resetting between successive encoding operations. We show that the quantum information may be spread over many static spins in the memory chain, making the mechanism resistent to spin decoherence and other imperfections. Among some potential architectures, we discuss implementing the memory in a photonic waveguide embedded with quantum dots, which is resilient to various possible errors.