Strong Atom-Electromagnetic Mode Coupling in Quantum Optics: Applications in Cavity Quantum Electrodynamics

Hiroki Takahashi, Ezra Kassa, Costas Christoforou +1 more

Strong coupling between an atom and an electromagnetic resonator is an important condition in cavity quantum electrodynamics. While strong coupling in various physical systems has been achieved so far, it remained elusive for single atomic ions. Here, we achieve a coupling strength of 2π×(12.3±0.1) MHz between a single ^{40}Ca^{+} ion and an optical cavity, exceeding both atomic and cavity decay rates which are 2π×11.5 and 2π×(4.1±0.1) MHz, respectively. We use cavity assisted Raman spectroscopy to precisely characterize the ion-cavity coupling strength and observe a spectrum featuring the normal mode splitting in the cavity transmission due to the ion-cavity interaction. Our work paves the way towards new applications of cavity quantum electrodynamics utilizing single trapped ions in the strong coupling regime for quantum optics and quantum technologies.

Claude Fabre

Gerhard Rempe, Robert J. Thompson, Harry J. Kimble

Claudiu Genes, André Xuereb, Guido Pupillo +1 more

We investigate a hitherto largely unexplored regime of cavity quantum electrodynamics in which a highly-reflective element positioned between the end-mirrors of a typical Fabry--P\'erot resonator strongly modifies the cavity response function, such that two longitudinal modes with different spatial parity are brought close to frequency degeneracy. We examine applications of this generic `optical coalescence' phenomenon for the generation of enhanced photon--phonon nonlinearities in optomechanics and atom--photon nonlinearities in cavity quantum electrodynamics with strongly-coupled emitters.

HERBERT WALTHER

Darrick E. Chang, Anders Søndberg Sørensen, Philip Hemmer +1 more

We describe a technique that enables strong, coherent coupling between individual optical emitters and electromagnetic excitations in conducting nanowires. The excitations in the wire are optical plasmons that are localized to sub-wavelength dimensions, and under realistic conditions optical emission can be almost entirely directed into the propagating plasmon modes via a mechanism analogous to cavity quantum electrodynamics. We describe an application of this technique involving efficient generation of single photons on demand, in which the plasmon on the nanowire is efficiently out-coupled to a dielectric waveguide. Finally, realistic sources of imperfections are analyzed.