Illinois researchers demonstrate multiphoton memory on a telecom chip platform

University of Illinois Urbana-Champaign researchers demonstrated a chip that stored up to 20 photons simultaneously for storage times reaching 1.2 microseconds, Tech Times reported. The Nano Letters paper describes quantum memory made from erbium-doped thin-film lithium niobate, a platform compatible with wafer-scale photonics manufacturing. The device temporarily transfers light's quantum state into erbium atoms and retrieves it later, allowing quantum operations to wait for synchronization. The experiment measured a quantum fidelity lower bound of 96.6%. Practical deployment faces substantial limits: internal retrieval efficiency fell to 0.7% at one microsecond, and the chip required a temperature of 30 millikelvin and a 1.5-tesla magnetic field. Useful quantum repeaters require retrieval efficiencies in the tens of percent.