Preserving Entanglement in a Solid-Spin System Using Quantum Autoencoders

TL;DR

This paper demonstrates that quantum autoencoders can effectively preserve entanglement in solid-spin systems, significantly extending the lifetime of entangled states by encoding them into more robust nuclear spin subspaces.

Contribution

It introduces a hybrid quantum-classical training method for quantum autoencoders to protect entanglement in solid-state systems, achieving a three orders of magnitude increase in entangled state lifetime.

Findings

Extended Bell state lifetime from 2.22 μs to 3.03 ms

Successfully encoded entangled states into nuclear spins

Demonstrated universal applicability of quantum autoencoders

Abstract

Entanglement, as a key resource for modern quantum technologies, is extremely fragile due to the decoherence. Here, we show that a quantum autoencoder, which is trained to compress a particular set of quantum entangled states into a subspace that is robust to decoherence, can be employed to preserve entanglement. The training process is based on a hybrid quantum-classical approach to improve the efficiency in building the autoencoder and reduce the experimental errors during the optimization. Using nitrogen-vacancy centers in diamond, we demonstrate that the entangled states between the electron and nuclear spins can be encoded into the nucleus subspace which has much longer coherence time. As a result, lifetime of the Bell states in this solid-spin system is extended from 2.22 {\pm} 0.43 {\mu}s to 3.03 {\pm} 0.56 ms, yielding a three orders of magnitude improvement. The quantum autoencoder approach is universal, paving the way of utilizing long lifetime nuclear spins as immediate-access quantum memories in quantum information tasks.