6 research outputs found
Phonon counting thermometry of an ultracoherent membrane resonator near its motional ground state
Generation of non-Gaussian quantum states of macroscopic mechanical objects
is key to a number of challenges in quantum information science, ranging from
fundamental tests of decoherence to quantum communication and sensing. Heralded
generation of single-phonon states of mechanical motion is an attractive way
towards this goal, as it is, in principle, not limited by the object size. Here
we demonstrate a technique which allows for generation and detection of a
quantum state of motion by phonon counting measurements near the ground state
of a 1.5 MHz micromechanical oscillator. We detect scattered photons from a
membrane-in-the-middle optomechanical system using an ultra-narrowband optical
filter, and perform Raman-ratio thermometry and second-order intensity
interferometry near the motional ground state ( phonons).
With an effective mass in the nanogram range, our system lends itself for
studies of long-lived non-Gaussian motional states with some of the heaviest
objects to date.Comment: 11 pages, 10 figure
Measurement of particle motion in optical tweezers embedded in a Sagnac interferometer
We have constructed a counterpropagating optical tweezers setup embedded in a
Sagnac interferometer in order to increase the sensitivity of position tracking
for particles in the geometrical optics regime. Enhanced position determination
using a Sagnac interferometer has previously been described theoretically by
Taylor et al. [Journal of Optics 13, 044014 (2011)] for Rayleigh-regime
particles trapped in an antinode of a standing wave. We have extended their
theory to a case of arbitrarily-sized particles trapped with
orthogonally-polarized counterpropagating beams. The working distance of the
setup was sufficiently long to optically induce particle oscillations
orthogonally to the axis of the tweezers with an auxiliary laser beam. Using
these oscillations as a reference, we have experimentally shown that
Sagnac-enhanced back focal plane interferometry is capable of providing an
improvement of more than 5 times in the signal-to-background ratio,
corresponding to a more than 30-fold improvement of the signal-to-noise ratio.
The experimental results obtained are consistent with our theoretical
predictions. In the experimental setup, we used a method of optical
levitator-assisted liquid droplet delivery in air based on commercial inkjet
technology, with a novel method to precisely control the size of droplets.Comment: 14 pages, 8 figure
High-frequency broadband laser phase noise cancellation using a delay line
Laser phase noise remains a limiting factor in many experimental settings,
including metrology, time-keeping, as well as quantum optics. Hitherto this
issue was addressed at low frequencies, ranging from well below 1 Hz to
maximally 100 kHz. However, a wide range of experiments, such as, e.g., those
involving nanomechanical membrane resonators, are highly sensitive to noise at
higher frequencies in the range of 100 kHz to 10 MHz, such as nanomechanical
membrane resonators. Here we employ a fiber-loop delay line interferometer
optimized to cancel laser phase noise at frequencies around 1.5 MHz. We achieve
noise reduction in 300 kHz-wide bands with a peak reduction of more than 10 dB
at desired frequencies, reaching phase noise of less than -160 dB (rad/Hz)
with a Ti:AlO laser. These results provide a convenient noise reduction
technique to achieve deep ground-state cooling of mechanical motion.Comment: 12 pages, 6 figure
Visualization 1: Optical manipulation for studies of collisional dynamics of micron-sized droplets under gravity
Coalescence of two droplets while the bottom droplet is trapped by laser light Originally published in Optics Express on 23 January 2017 (oe-25-2-1391