Quantum Memories

Room temperature quantum light-matter interfaces.

Achieving robust quantum operation at room temperature has been labeled as impossible. In our recent work we have built a fully-functional polarization qubit quantum memory operating at 330 K. A persisting and careful expansion of maturing quantum technologies into regimes that enable resource-sensible and room temperature operation is the key towards achieving robust and deployable quantum technologies. We have created a fully portable room temperature quantum memory which is an attractive alternative compared to its cold atom and cryogenic system counterparts. By exploiting the capabilities of photon-atom systems and merging them with the advantages of room temperature operation, a novel, tractable platform for an elementary quantum network now presents itself. This is the technological core to achieve ultra-secure communication using quantum cryptography, the materialization of powerful quantum simulators and the facilitation of a future distributed quantum computation system.

We have characterized the optimal performance of room temperature quantum light-matter interfaces and attained complete quantum memory operation for polarization qubits in a warm 87Rb atomic vapor. We obtained an average fidelity above 98%. This result is well above the maximum fidelity achievable considering the more elaborate classical strategy exploiting the non-unitary character of the memory efficiency. This is the first time such important boundary has been crossed with a room temperature device, rendering our system suitable for true quantum operation either as a memory or as a two qubit gate device.

The obtained results from this work led to several publications in which we have optimized the memory from a quantum mechanical point of view, cascaded two memory processes including memory-built photon shaping and created a BB84-like quantum communication network with an embedded quantum memory.

We have designed and built three generations of these inexpensive and commercialization friendly devices, having all capabilities necessary for quantum repeater operation. Our latest ultra-compact model is plug-and-play and is currently in use, or will soon be, in different international locations as a test-bed of important capabilities, namely: entanglement distribution (Brookhaven National Laboratories), operation with short photons (Stockholm KTH, Sweden) and satellite communication compatibility (University of Padova, Italy).

From an engineering viewpoint the technology has been improved and elements integrated into a coherent and functional fully-portable room-temperature quantum memory especially equipped for operation outside of the laboratory and will soon be used to build a first-of-its-kind quantum network.