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HL: Fachverband Halbleiterphysik
HL 41: Focus Session: Nanomechanical Systems for Classical and Quantum Sensing III (joint session HL/DY/TT/QI)
HL 41.2: Invited Talk
Thursday, March 21, 2024, 10:00–10:30, EW 202
Quantum mechanics-free subsystem with mechanical oscillators — •Laure Mercier de Lepinay1, Caspar Ockeloen-Korppi1, Matthew Woolley2, and Mika Sillanpää1 — 1Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland — 2School of Engineering and Information Technology, UNSW Canberra, ACT, 2600, Australia
Quantum mechanics sets a limit on the precision of the continuous measurement of an oscillator's position. However, with an adequate coupling configuration of two oscillators, it is possible to build an oscillator-like subsystem of quadratures isolated from quantum and classical backaction which therefore does not suffer from this limit. We realize such a quantum mechanics-free subsystem using two micromechanical drumheads coupled to microwave cavities. Multitone phase-stable microwave pumping of the system allows to implement the necessary effective coupling configuration. We first demonstrate the measurement of two collective quadratures, evading backaction simultaneously on both of them, obtaining a total noise within a factor of 2 of the full quantum limit. Secondly, this measurement technique is directly adapted to the detection of continuous variable entanglement which is based, according to the Duan criterion, on variance estimates of two collective quadratures. We therefore verify the stabilized quantum entanglement of the two oscillators deeper than had been possible before for macroscopic mechanical oscillators.
Keywords: Optomechanics; Nanomechanics; Quantum entanglement; Electromechanics; Superconducting circuits