Speaker
Description
In this talk I will outline quantum-enhanced sensing modalities for nanoscale displacement and phase
sensing. Optomechanical devices use optical readout of micro/nano-electromechanical systems (MEMS)
displacement in order to transduce displacement and phase signals. New detection modes that focus on
ultrasonic measurements have brought the shot noise of the optical field into play when transducing
signals near resonance, allowing for shot noise limited measurements even at room temperature.
However, state of the art approaches to date have been unable to leverage the lower noise floor away
from the mechanical resonance frequency because minimum resolvable signals fall below the noise floor
off-resonance. As a result, many MEMS measurement techniques can only probe the RF responses of
materials or fields at discrete mechanical frequencies, with slow measurements associated with
micromechanical ringdown times that are highly susceptible to nonlinear dynamics. In the shot noise
limited regime, far below the back-action limit, these devices are good candidates for quantum sensing,
where quantum effects like entanglement are used to enhance the readout of optical beam
displacements, revealing signals that were previously buried in the noise. For example, in the case of
atomic force microscopy, the ability to lower the noise floor beyond current classical limits enables
broadband materials characterization critical to describing electronic dynamics in complex materials
with orders of magnitude faster acquisition times than are currently available. I will compare and
contrast two common readout techniques, with added quantum enhancement: direct detection readout
and interferometric readout. I will outline a new scheme that relies on squeezed light and nonlinear
interferometry to move nanoscale displacement sensing, phase sensing, and quantum imaging below
the shot noise limit.
