Nanoscale mechanical oscillators

Introduction
 

Optomechanics offers a range of enticing opportunities for exploring the fundamental physics of quantum-limited continuous position and force measurements. In state-of-the art nano- and micro- optomechanical devices at cryogenic temperatures the measurement rate can exceed the mechanical thermal decoherence rate [1], providing experimental access to the regime where the dynamics of an oscillator is driven primarily by the quantum back-action of the meter light field. In this regime new quantum effects come into play, which can be harnessed to improve the measurement signal to noise ratio. In this project, we seek to fabricate devices capable of operation deep in the quantum regime both at cryogenic temperatures and room temperature and thereafter use them to study quantum measurements [2,3].

Extreme stresses can be produced in nanoscale structures. This feature was recently used in our laboratory to realize exceptionally low mechanical dissipation, when combined with “soft-clamping” — a form of phononic engineering. Specifically, using a non-uniform phononic crystal pattern, we colocalized the strain and flexural motion of a free-standing Si3N4 nanobeam to produce string-like modes with quality (Q) factors as high as 800 million and Q × frequency exceeding 1015 Hz [4]. We now seek to integrate these ultra-high Q oscillators with an optical cavity for quantum optomechanics.

References

[1] D.J. Wilson, V. Sudhir, N. Piro, R. Schilling, A. H. Ghadimi and T. J. Kippenberg. “Measurement-based control of a mechanical oscillator at its thermal decoherence rate”. Nature 524, 325–329 (2015)

[2] V. Sudhir, R. Schilling, S. A. Fedorov, H. Schütz, D. J. Wilson, and T. J. Kippenberg. “Appearance and Disappearance of Quantum Correlations in Measurement-Based Feedback Control of a Mechanical Oscillator”, Phys. Rev. X 7, 011001

[3] V. Sudhir, D. J. Wilson, R. Schilling, H. Schütz, S. A. Fedorov, A. H. Ghadimi, A. Nunnenkamp, and T. J. Kippenberg. “Quantum Correlations of Light from a Room-Temperature Mechanical Oscillator”, Phys. Rev. X 7, 031055

[4] A. H. Ghadimi,* S. A. Fedorov,* N. J. Engelsen,* M. J. Bereyhi, R. Schilling, D. J. Wilson and T. J. Kippenberg. “Elastic strain engineering for ultralow mechanical dissipation”, Science 10.1126/science.aar6939 (2018).