Researchers at NASA’s Jet Propulsion Laboratory have designed an optical quantum memory device capable of storing photonic qubits for use in all-optical quantum computers and quantum communications networks.

The researchers’ quantum transponder could be used to make quantum repeaters that would extend the distances covered by emerging quantum cryptography systems.

The scheme calls for encoding pairs of quantum bits in sets of four photons in such a way that the two qubits can be read even if one of the four photons is lost. Qubits would be sent into a fiber loop and a simple quantum computer would correct for errors caused by photons being absorbed by the fiber.