Superfluid Optomechanics With Phononic Nanostructures

Abstract

In quantum optomechanics, finding materials and strategies to limit losses has been crucial to the progress of the field. Recently, superfluid 4 He was proposed as a promising mechanical element for quantum optomechanics. This quantum fluid shows highly desirable properties (e.g. extremely low acoustic loss) for a quantum optomechanical system. In current implementations, superfluid optomechanical systems suffer from external sources of loss, which spoils the quality factor of resonators. In this work, we propose a new implementation, exploiting nanofluidic confinement. Our approach, based on acoustic resonators formed within phononic nanostructures, aims at limiting radiation losses to preserve the intrinsic properties of superfluid 4 He. In this work, we estimate the optomechanical system parameters. Using recent theory, we derive the expected quality factors for acoustic resonators in different thermodynamic conditions. We calculate the sources of loss induced by the phononic nanostructures with numerical simulations. Our results indicate the feasibility of the proposed approach in a broad range of parameters, which opens new prospects for more complex geometries.

Third sound detectors in accelerated motion

“…As the two closely agree at high frequencies, a measurement of F(ω; T ) at high frequencies determines F Lin (ω; T ) over our full frequency range, by the linearity of (S51). A measurement of F(ω; T ) at lower frequencies, where F(ω; T ) and F Lin (ω; T ) differ, then determines S δ (ω) (14) at the lower frequencies.…”

“…Optomechanical systems have proved to be ideal for achieving high levels of sensitivity in the detection of mechanical motion. Recently, such systems have been utilised effectively to investigate the dynamics of superfluid excitations with remarkable precision, including both acoustic phonons [11][12][13][14] and surface excitations [15][16][17][18][19][20]. Using a laser as a probe field, height fluctuations δh on the surface of superfluid helium are transduced into phase fluctuations ψ in the laser,…”

On the Interaction of Massive Photons and Mechanical Oscillators in Cavity Optomechanics: Basic Model and Quantization

“…[55,61] Superfluids provide convenient methods for mitigating losses in cavity optomechanical systems. [62] These systems are characterized by extremely low acoustic losses and have a well-established theoretical foundation. [63] In hybrid optomechanical systems that involve cold atom gas-filled optical cavities, the exceptional isolation of the atomic ensemble from mechanical disturbances, coupled with its strong polarizability near the atomic resonance frequency, makes these optomechanical systems highly sensitive to quantum radiation pressure fluctuations.…”

Third sound detectors in accelerated motion

“…We show that long-wavelength perturbations on the surface of thin film superfluid helium-4, commonly referred to as third sound [18], obey an effective quantum field theory [19,20]. In investigating the dynamics of superfluids, including both surface excitations [21][22][23][24][25][26][27][28][29][30] and acoustic phonons [31][32][33][34], optomechanical systems have been effectively utilised with remarkable precision.…”