A study that includes DAALI research groups from led by Arno Rauschenbeutel, from Humboldt University (HUB), and Barak Dayan, from The Weizmann Institute of Science, shows the effects of the interactions of light and matter under warm atomic vapor conditions.
Efficient interaction between light and matter and particularly the faithful coherent mapping between photons and atomic excitations lie at the heart of many quantum optics processes and applications, such as quantum networks. One appealing platform is room-temperature atomic vapor, which is successfully employed in first-generation quantum technologies, including atomic clocks and magnetometers, and quantum light sources and memories. Light–matter interaction can be enhanced by a tight optical mode volume and by a collective coupling of this mode to an ensemble of atoms.
The team fabricated an extremely thin optical fiber that supports a super-extended mode with a diameter as large as 13 times the optical wavelength, residing almost entirely outside the fiber and guided over thousands of wavelengths (5 mm), to couple guided light to warm atomic vapor. This unique configuration balances between strong confinement, as evident by saturation powers as low as tens of nW, and long interaction times with the thermal atoms, thereby enabling fast and coherent interactions.
With the setup, they are able to demonstrate narrow coherent resonances (tens of MHz) of electromagnetically induced transparency for signals at the single-photon level and long relaxation times (10 ns) of atoms excited by the guided mode. The dimensions of the guided mode’s evanescent field are compatible with the Rydberg blockade mechanism, making this platform particularly suitable for observing quantum nonlinear optics phenomena.
