Abstract
Nanoscale mechanical oscillators are sensitive to a wide range of forces, and
are the subject of studies into fundamental quantum physics. They can be used
for mass detection at the single proton level, position measurements to the
quantum limit, and they have found application in genetics, proteomics,
microbiology and studies of DNA. Their sensitivity is limited by dissipation to
the environment, which reduces the mechanical quality factor $Q_m$. Here
we realize a nanomechanical rotor with remarkably high $Q_m$, by
optically levitating a silicon nanorod and periodically driving its rotation
with circularly polarized light. We frequency-lock the nanorod's motion to the
periodic drive, resulting in ultra-stable rotations, with a stability close to
that of the drive. While operating at room temperature, and gas pressures of a
few millibar, our system exhibits an effective $Q_m$ of $10^11$, and a
$Q_m$-frequency product of $10^17$Hz, three orders of magnitude greater
than measured in any other experiment. This frequency stability yields an
unprecedentedly high room temperature torque sensitivity of $0.24$zNm and a
relative pressure sensitivity of $0.3$%. In addition, the external drive allows
us to tune the rotational frequency by almost $10^12$ linewidths, and the
ability to make local phase sensitive measurements allows real-time readout,
offering a new paradigm of flexibility in sensing applications.
Description
Optically driven ultra-stable nanomechanical rotor
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