Long-Lived Noble-Gas Spin-Based Optical Quantum Memory

Many quantum technologies use light to carry information, but future systems will also need a way to pause, synchronize, and release light without destroying its quantum properties. A quantum memory is a device that performs this function by storing the quantum state of light in matter and retrieving it later on demand. Existing quantum-memory approaches have made important progress, but many involve tradeoffs among storage time, efficiency, added noise, and hardware complexity. This project will develop a compact, non-cryogenic quantum memory based on noble-gas nuclear spins in a sealed glass cell. Noble-gas spins, such as helium-3, can preserve spin coherence for long times, but they do not interact directly with light in a convenient way. The project addresses this challenge by using alkali-metal atoms as an intermediary between light and helium-3 nuclear spins. A light pulse is mapped onto collective spin motion, stored in helium-3, and later converted back into light on demand. The work will test whether warm, sealed-cell spin devices can provide practical quantum memories for future quantum networks, communication systems, and quantum-enhanced sensors. The project will also train graduate and undergraduate students in quantum hardware engineering, including optics, low-noise measurement, magnetic-field control, and quantitative device benchmarking. Education and outreach activities will include high-school engagement, undergraduate research opportunities, course integration, and dissemination of instructional and analysis materials. The research will realize and benchmark an optical quantum memory based on a coupled alkali-helium-3 spin system. Potassium provides optically addressable electronic spins, while spin-exchange collisions couple these spins to long-lived helium-3 nuclear spins. The optical write/read interface uses a far-detuned double-pass Faraday interaction, in which the polarization of light couples dispersively to collective spin variables while reducing absorption in the pressure-broadened warm vapor. The project is organized in three stages. First, it will demonstrate repeatable write-store-read operation for well-defined optical temporal modes and map retrieval efficiency, storage decay, and temporal-mode matching versus operating conditions. Second, it will characterize the device as a continuous-variable optical channel. Third, it will test nonclassical-state operation by preparing a squeezed collective-spin state in the memory mode and retrieving it as an optical temporal mode using. The expected outcome is a demonstrated non-cryogenic noble-gas optical memory platform, together with experimentally validated design rules linking performance to the operating parameters. The work will establish whether noble-gas nuclear spins can combine long storage times with a practical optical interface, addressing a gap in current quantum-memory platforms. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.