Cavity-enhanced long-distance coupling of an atomic ensemble to a micromechanical membrane

Abstract

We discuss a hybrid quantum system where a dielectric membrane situated inside an optical cavity is coupled to a distant atomic ensemble trapped in an optical lattice. The coupling is mediated by the exchange of sideband photons of the lattice laser, and is enhanced by the cavity finesse as well as the square root of the number of atoms. In addition to observing coherent dynamics between the two systems, one can also switch on a tailored dissipation by laser cooling the atoms, thereby allowing for sympathetic cooling of the membrane. The resulting cooling scheme does not require resolved sideband conditions for the cavity, which relaxes a constraint present in standard optomechanical cavity cooling. We present a quantum mechanical treatment of this modular open system which takes into account the dominant imperfections, and identify optimal operation points for both coherent dynamics and sympathetic cooling. In particular, we find that ground state cooling of a cryogenically pre-cooled membrane is possible for realistic parameters.

The role of mode match in fiber cavities

“…In particular the radius of curvature of the curved fiber tip as well as the range of usable cavity lengths has been adapted to the specific fiber to maximize the mode match, leading to the de-sired reflectivity on resonance. Our studies pave the way for the implementation of atom-membrane hybrid quantum systems in a low milli-Kelvin cryogenic environment, which shall allow sympathetic cooling of the membrane to its quantum mechanical ground state by laser cooling the atoms 12,13 . The paper is organized as follows: After a short reminder on basic properties of Fabry-Pérot cavities, we introduce an analytical model to calculate reflection and transmission properties of asymmetric fiber cavities and discuss the role of mode matching.…”

“…For certain applications, e.g. the integral use of such fiber cavities in quantum hybrid systems [12][13][14] , the most important aspect is a bidirectional light mediated coupling between the two constituents (see Fig. 1).…”

Ground-state cooling of a dispersively coupled optomechanical system in the unresolved sideband regime via a dissipatively coupled oscillator

“…Thus, a solution to the difficult problem of cooling the dispersively coupled oscillator is provided. Note that this approach is not the first reported technique of this kind; however, the existing schemes for ground-state cooling in the unresolved sideband, such as cooling with optomechanically induced transparency (OMIT) [33,34], coupled-cavity configurations [35,36], atom-optomechanical hybrid systems [37][38][39][40][41][42][43][44], and the recently proposed scheme using quantum non-demolition interactions [45], require multiple driving lasers, multiple optical modes, high-quality cavities, and ground-state atom ensembles. Compared with those methods, our proposal offers a simpler option for cases in which dissipative coupling is accessible.…”

Quantum decoherence of an anharmonic oscillator monitored by a Bose-Einstein condensate

“…There are several proposals aimed at achieving this by employing atoms in a cavity with a moving mirror [7][8][9], or by coupling atoms by means of a reflective membrane, where the lattice trapping the atoms is built by reflecting a laser beam off the membrane [10,11].…”