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Title: Nano-acoustic resonator with ultralong phonon lifetime

The energy damping time in a mechanical resonator is critical to many precision metrology applications, such as timekeeping and force measurements. We present measurements of the phonon lifetime of a microwave-frequency, nanoscale silicon acoustic cavity incorporating a phononic bandgap acoustic shield. Using pulsed laser light to excite a colocalized optical mode of the cavity, we measured the internal acoustic modes with single-phonon sensitivity down to millikelvin temperatures, yielding a phonon lifetime of up toτph,01.5seconds (quality factorQ=5×1010) and a coherence time ofτcoh,0130microseconds for bandgap-shielded cavities. These acoustically engineered nanoscale structures provide a window into the material origins of quantum noise and have potential applications ranging from tests of various collapse models of quantum mechanics to miniature quantum memory elements in hybrid superconducting quantum circuits.

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Publication Date:
Journal Name:
Page Range or eLocation-ID:
p. 840-843
American Association for the Advancement of Science (AAAS)
Sponsoring Org:
National Science Foundation
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