Optical Cavity QED: Fundamentals and application as a single-photon light source

H. Snijders, J. A. Frey, J. Norman +6 more

An ordered stream of single photons is fundamentally different from conventional light, which features bunches of random numbers of photons. Single-photon sources are essential for emerging technologies in $e.g.$ quantum cryptography and computing, but widespread use of bright quantum-dot sources has been thwarted by the need for complex optical setups. Thus the authors present a $f\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}b\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r-i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}g\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}d$ source of high-quality single photons. This marriage with conventional optical-fiber technology will not only promote broad use in quantum photonics, but also may enable fundamental studies in fields from microscopy to quantum metrology, by significantly simplifying experiments.

Jonathan R. Tischler

Kazuki

Henk Snijders, J. A. Frey, Justin Norman +6 more

An ordered stream of single photons is fundamentally different from conventional light, which features bunches of random numbers of photons. Single-photon sources are essential for emerging technologies in $e.g.$ quantum cryptography and computing, but widespread use of bright quantum-dot sources has been thwarted by the need for complex optical setups. Thus the authors present a $f\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}b\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r-i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}g\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}d$ source of high-quality single photons. This marriage with conventional optical-fiber technology will not only promote broad use in quantum photonics, but also may enable fundamental studies in fields from microscopy to quantum metrology, by significantly simplifying experiments.

Harry J. Kimble

Danial Shadmany, Aishwarya Kumar, Anna Soper +8 more

From fundamental studies of light-matter interaction to applications in quantum networking and sensing, cavity quantum electrodynamics (QED) provides a platform-crossing toolbox to control interactions between atoms and photons. The coherence of such interactions is determined by the product of the single-pass atomic absorption and the number of photon round-trips. Reducing the cavity loss has enabled resonators supporting nearly 1-million optical roundtrips at the expense of severely limited optical material choices and increased alignment sensitivity. The single-pass absorption probability can be increased through the use of near-concentric, fiber or nanophotonic cavities, which reduce the mode waists at the expense of constrained optical access and exposure to surface fields. Here we present a new high numerical-aperture, lens-based resonator that pushes the single-atom-single-photon absorption probability per round trip close to its fundamental limit by reducing the mode size at the atom below a micron while keeping the atom mm-to-cm away from all optics. This resonator provides strong light-matter coupling in a cavity where the light circulates only ~ 10 times. We load a single 87Rb atom into such a cavity, observe strong coupling, demonstrate cavity-enhanced atom detection with imaging fidelity of 99.55(6) percent and survival probability of 99.89(4) percent in 130 microseconds, and leverage this new platform for a time-resolved exploration of cavity cooling. The resonator's loss-resilience paves the way to coupling of atoms to nonlinear and adaptive optical elements and provides a minimally invasive route to readout of defect centers. Introduction of intra-cavity imaging systems will enable the creation of cavity arrays compatible with Rydberg atom array computing technologies, vastly expanding the applicability of the cavity QED toolbox.