Theoretical Physics

3 December 2012
Time: 11:00 to 12:00
Location: Roger Stevens Lecture Theatre LT19 (10.19)

Professor Per Delsing (Chalmers University of Technology, Sweden)

Local probing of propagating acoustic waves in a gigahertz echo chamber

Departmental seminar. In the same way that micro-mechanical resonators resemble guitar strings and drums, surface acoustic waves resemble the sound these instruments produce, but moving over a solid surface rather than through air. In contrast with oscillations in suspended resonators, such propagating mechanical waves have not before been studied near the quantum mechanical limits. In a recent paper [1], we have demonstrated local probing of surface acoustic waves with a displacement sensitivity of 30 am_RMS/√Hz and detection sensitivity on the single-phonon level after averaging, at a frequency of 932 MHz. Our probe is a piezoelectrically coupled single-electron transistor, which is sufficiently fast, non-destructive and localized to enable us to track pulses echoing back and forth in a long acoustic cavity, self-interfering and ringing the cavity up and down. Prospects include quantum investigations of phonon–phonon interactions, and acoustic coupling to superconducting qubits .[1] M.V. Gustafsson et al. Nature Physics, 8, 338 (2012)



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