ESPCI web site
April 17 at 2:00 pm (Paris time)
Room Boreau, building C, 2nd floor
Drum resonators for Casimir force detection
Optomechanical drum resonators have allowed many breakthroughs in microwave optomechanics, such as the implementation of active cooling down to the ground state [1], squeezed states [2] and entangled states [3] of center-of-mass displacement. Here, we show that drum resonators made of closely spaced metallic membranes used in many quantum optomechanical experiments are in fact expected to be impacted to a drastic extent by the Casimir potential, applying a stress comparable in order of magnitude to the stress incurred due to relative thermal contractions when cooling the device to cryogenic temperatures.
By using a two-tone optomechanical scheme to drive such an oscillator coupled to a microwave on-chip cavity, we observe a strongly nonlinear mechanical behavior which we find, by matching it with continuation simulations, to be compatible in magnitude and distance-scaling with the expected Casimir force. We exclude several other sources of nonlinearity as origins of the observed behavior to argue that it is indeed very likely due to the Casimir effect. We also present our work on potential patches in these devices [4], as these may have the same qualitative effect as the Casimir force, and propose qualitative and quantitative arguments to exclude other sources of non-linearity.
Finally, we show that the high sensitivity of these superconducting drum resonators to the Casimir force would allow to investigate the difference between the normal-state and superconducting-state Casimir force. The measurement of this difference has indeed been proposed to shed light on a long-standing discrepancy between theoretical and experimental values of the Casimir force [5].
[1] J. D. Teufel et al., Nature 475, 359–363 (2011)
[2] F. Lecocq, J. B. Clark, R. W. Simmonds, J. Aumentado, and J. D. Teufel, Physical Review X 5, 41037 (2015), J. M. Pirkkalainen, E. Damskägg, M. Brandt, F. Massel, and M. A. Sillanpää, Physical Review Letters 115, 243601 (2015), E. E. Wollman et al., Science 349, 952-955 (2015)
[3] C. F. Ockeloen-Korppi et al., Nature 556, 478 - 482 (2018)
[4] M. H. J. de Jong, and L. Mercier de Lépinay, arXiv:2408.16323 (submitted)
[5] G. Bimonte, Physical Review A 78, 62101 (2008)
