Photonics has the potential to serve as a uniquely powerful platform for quantum information processing, operating at room temperature, at high clock speeds and providing a natural networking capability. However the difficulty in implementing deterministic entangling operations has so far prevented photonic architectures from achieving this potential. One way to solve this problem is by rendering probabilistic linear interactions deterministic with active synchronisation of successful operations. Quantum memories are needed for this purpose, but the requirements for this application are different to the ‘conventional’ requirements known from quantum repeaters. For synchronisation applications, only short storage times are needed, yet high efficiency, simplicity, broad bandwidth (‘fast operation’) and the ability to operate in ambient conditions, are extremely desirable features, as a quantum information processing system would comprise hundreds or thousands of these devices.
Here I report on our recent results demonstrating a noise-free quantum memory based on off-resonant cascaded absorption (ORCA) in a warm alkali vapour. The memory is broadband, while also being technically simple, and potentially compatible with (hollow) fibre integration.