Physics Colloquium : "Room-temperature quantum memories from nanoseconds to hours"

Mon, 17/06/2019 - 12:00 to 13:30

Levin building, Lecture Hall No. 8
Lecturer: Dr. Ofer Firstenberg, Weizmann Institute of Science Abstract: Warm atomic gasses are among the simplest quantum systems, offering real-life applications in deployable millimeter-size devices. They can strongly couple to optical fields and exhibit superb coherence properties at or above room temperature. Indeed, atomic gasses are at the heart of miniature atomic clocks and inside the most sensitive magnetometers and gyroscopes. We explore various processes that enable the coherent storage of photons in atomic gasses, namely in alkali vapors and noble gasses. In these systems, the optical field could be mapped onto the superposition between electronic orbitals, between electronic spins, or between nuclear spins. These distinct degrees of freedom feature different coupling mechanisms to light and to the environment, which determine the bandwidth, efficiency, noise, and lifetimes of the realized quantum memories. Electronic orbital excitations provide for fast memories of nanosecond-long photons, suitable for quantum network synchronization. We study these memories with single photons and consider their implementation via tapered fibers and their integration with Rydberg-level excitations for quantum nonlinear optics. Electronic spin excitations are fundamentally slower, but could exhibit much longer lifetimes. By identifying spin states unaffected by spin-exchange collisions, we demonstrate record memory lifetimes approaching one second at room temperature. Finally, nuclear spins of rare noble-gasses can maintain coherence for hours. We develop theoretical and experimental tools for using these spins as quantum memories, paving the way to extreme quantum optics and sensing applications with hour-long lifetimes.