Detecting atomic rotation via cavity optomechanics

N. Pradhan, Pardeep Kumar, Rina Kanamoto +3 more

We present numerical simulations of the cavity optomechanical detection of persistent currents and bright solitons in an atomic Bose-Einstein condensate confined in a ring trap. This paper describes a technique that measures condensate rotation , in real time, and with minimal destruction, in contrast to currently used methods, all of which destroy the condensate completely. For weakly repulsive interatomic interactions, the analysis of persistent currents extends our previous few-mode treatment of the condensate [P. Kumar ] to a stochastic Gross-Pitaevskii simulation. For weakly attractive atomic interactions, we present the first analysis of optomechanical detection of matter-wave soliton motion. We provide optical cavity transmission spectra containing signatures of the condensate rotation, sensitivity as a function of the system response frequency, and atomic density profiles quantifying the effect of the measurement backaction on the condensate. We treat the atoms at a mean-field level and the optical field classically, account for damping and noise in both degrees of freedom, and investigate the linear as well as nonlinear response of the configuration. Our results are consequential for the characterization of rotating matter waves in studies of atomtronics, superfluid hydrodynamics, and matter-wave soliton interferometry. Published by the American Physical Society 2024

Nathaniel Brahms, Daniel W. C. Brooks, Sydney Schreppler +2 more

Dan Stamper-Kurn

Xin Wang, Fei-Fan Ren, Song Hee Han +2 more

Rydberg atoms have attracted considerable attention due to their several singular properties, such as strong long-range interactions, extremely long lifetimes, and very large polarizability. These characteristics make Rydberg atoms a good candidates for cavity quantum electrodynamics, quantum information, and many-body physics. Recently, the study of optomechanics has become a rapidly developing field due to its important applications in cooling of mechanical resonators, implementing precision measurements, slowing light, and preparing quantum entanglement. Obviously, optomechanical systems pave the way for quantum information processing and quantum communication. Specially, there is significant interest in quantum optomechanics due to its high compatibility that can be combined, to build hybrid systems for certain purposes, with the ultracold atoms, a superconducting single electron transistor, a magnetostrictive actuation, a charged oscillator resonator, etc. In this work, we investigate the optomechanically induced transparency (OMIT) and the resulting effect of slow light in a hybrid system composed of a Rydberg atomic ensemble embedded inside a simple optomechanical cavity. As a typical effect of destructive quantum interference, OMIT is widely used in quantum optics and quantum information processing. Based on the Rydberg blockade effect, a Rydberg atomic ensemble in the same blockade region embedded inside an optomechanical cavity can be regarded as a superatom that contains only a single Rydberg excitation. Therefore, the problem of exponentially increasing system size with the number of atoms increasing can be circumvented easily. The hybrid system becomes a coupling between a Rydberg superatom and an optomechanical cavity and the coupling strength is enhanced by a factor of square root of the number of atoms in the ensemble. In this system, the perfect OMIT, namely, an ideal OMIT dip with a very narrow window, can be attained when an effect of non-rotating wave approximation (NRWA) is considered. Further, we demonstrate that the term of NRWA plays a key important role in achieving perfect OMIT by comparing the optomechanical spectra obtained with and without NRWA effects. Our results show that in the resolved sideband regime the higher the quality factor of cavity is, the stronger the slow light effect becomes in the window of the perfect OMIT. Particularly, in achieving the ultraslow light, the long lifetime of the Rydberg atom shows its superiority.

Ke-ye, Zhang, Lǔ +4 more

N. Pradhan, Rina Kanamoto, Mishkatul Bhattacharya +1 more

The Andreev-Bashkin (AB) effect, corresponding to the dissipationless dragging of one superfluid by another, was predicted in the early 1970s but has so far eluded experimental detection. In this work, we theoretically introduce a detection paradigm and show that it enables the observation of the hitherto undetected AB effect for realistic parameters. We accomplish this by using the powerful techniques of cavity optomechanics, which were crucial to the observation of gravitational waves, on a spinor ring Bose-Einstein condensate. In contrast to established AB detection methods, our scheme allows for real-time, , minimally destructive and three orders-of-magnitude-more-sensitive measurement of the AB effect. Our proposal, which considers persistent currents in weakly repulsive atomic condensates and amplifies the AB signal using a dynamic Bragg spectroscopy technique, is supported by numerical simulations of the stochastic Gross-Pitaevski equation, which agree very well with our analytic Bogoliubov–de Gennes calculations. Our work suggests a tool for sensitively and nondestructively probing the dynamics of rotationally interacting superfluids using cavities and has fundamental implications for ongoing studies of superfluid hydrodynamics, atomtronics, matter-wave interferometry, and cavity optomechanical sensing.