Southwest Quantum Information and Technology

Exploring the macroscopic quantum physics of motion with superfluid He-4

Presenting Author: Laura De Lorenzo, Schwab group (IQIM, Caltech)
Contributing Author(s): A. Pearlman, K. Schwab

We demonstrate the utility of superfluid helium-4 as an extremely low loss optomechanical element. We form an optomechanical system with a cylindrical niobium superconducting TE011 resonator whose 40 cm^3 inner cylindrical cavity is filled with He-4. Coupling is realized via the variations in permittivity resulting from the density profile of the acoustic modes. Acoustic losses in helium-4 below 500 mK are governed by the intrinsic nonlinearity of sound, leading to an attenuation which drops as T^4, indicating the possibility of quality factors (Q) over 10^10 at 10 mK. In our lowest loss mode, we demonstrate this T^4 law at temperatures down to 50 mK, realizing an acoustic Q of 1.35*10^8 at 8.1 kHz. When coupled with a low phase noise microwave source, we expect this system to be utilized as a probe of macroscopic quantized motion, for precision measurements to search for fundamental physical length scales, and as a continuous gravitational wave detector. Our estimates suggest that a resonant superfluid acoustic system could exceed the sensitivity of current broad-band detectors for narrow-band sources such as pulsars.

Read this article online: http://authors.library.caltech.edu/45782/7/1367-2630_16_11_113020.pdf

(Session 13 : Saturday from 4:45 pm - 5:15 pm )