Unconditional Room Temperature Quantum Memory

TL;DR

This paper demonstrates an optical quantum memory using rubidium vapor at room temperature, achieving high fidelity storage and recall of quantum states without complex conditioning.

Contribution

It provides the first complete tomographic reconstruction of quantum states stored in rubidium vapor at 80°C with high fidelity, verifying quantum memory performance beyond the no-cloning limit.

Findings

Recall fidelity up to 98% for coherent pulses

Memory operates at room temperature with simple setup

Verification confirms quantum advantage over classical limits

Abstract

Just as classical information systems require buffers and memory, the same is true for quantum information systems. The potential that optical quantum information processing holds for revolutionising computation and communication is therefore driving significant research into developing optical quantum memory. A practical optical quantum memory must be able to store and recall quantum states on demand with high efficiency and low noise. Ideally, the platform for the memory would also be simple and inexpensive. Here, we present a complete tomographic reconstruction of quantum states that have been stored in the ground states of rubidium in a vapour cell operating at around 80$^o$C. Without conditional measurements, we show recall fidelity up to 98% for coherent pulses containing around one photon. In order to unambiguously verify that our memory beats the quantum no-cloning limit we employ state independent verification using conditional variance and signal transfer coefficients.