20 research outputs found
Optomechanical transduction of an integrated silicon cantilever probe using a microdisk resonator
Sensitive transduction of the motion of a microscale cantilever is central to
many applications in mass, force, magnetic resonance, and displacement sensing.
Reducing cantilever size to nanoscale dimensions can improve the bandwidth and
sensitivity of techniques like atomic force microscopy, but current optical
transduction methods suffer when the cantilever is small compared to the
achievable spot size. Here, we demonstrate sensitive optical transduction in a
monolithic cavity-optomechanical system in which a sub-picogram silicon
cantilever with a sharp probe tip is separated from a microdisk optical
resonator by a nanoscale gap. High quality factor (Q ~ 10^5) microdisk optical
modes transduce the cantilever's MHz frequency thermally-driven vibrations with
a displacement sensitivity of ~ 4.4x10^-16 m\sqrt[2]{Hz} and bandwidth > 1 GHz,
and a dynamic range > 10^6 is estimated for a 1 s measurement.
Optically-induced stiffening due to the strong optomechanical interaction is
observed, and engineering of probe dynamics through cantilever design and
electrostatic actuation is illustrated
Sympathetic cooling of a membrane oscillator in a hybrid mechanical-atomic system
Sympathetic cooling with ultracold atoms and atomic ions enables ultralow
temperatures in systems where direct laser or evaporative cooling is not
possible. It has so far been limited to the cooling of other microscopic
particles, with masses up to times larger than that of the coolant atom.
Here we use ultracold atoms to sympathetically cool the vibrations of a
SiN nanomembrane, whose mass exceeds that of the atomic ensemble by a
factor of . The coupling of atomic and membrane vibrations is mediated
by laser light over a macroscopic distance and enhanced by placing the membrane
in an optical cavity. We observe cooling of the membrane vibrations from room
temperature to mK, exploiting the large atom-membrane
cooperativity of our hybrid optomechanical system. Our scheme enables
ground-state cooling and quantum control of low-frequency oscillators such as
nanomembranes or levitated nanoparticles, in a regime where purely
optomechanical techniques cannot reach the ground state.Comment: 11 pages, 4 figure
Spectroscopy of mechanical dissipation in micro-mechanical membranes
We measure the frequency dependence of the mechanical quality factor (Q) of
SiN membrane oscillators and observe a resonant variation of Q by more than two
orders of magnitude. The frequency of the fundamental mechanical mode is tuned
reversibly by up to 40% through local heating with a laser. Several distinct
resonances in Q are observed that can be explained by coupling to membrane
frame modes. Away from the resonances, the background Q is independent of
frequency and temperature in the measured range.Comment: 4 pages, 5 figure
Two-photon interference using background-free quantum frequency conversion of single photons from a semiconductor quantum dot
We show that quantum frequency conversion (QFC) can overcome the spectral
distinguishability common to inhomogeneously broadened solid-state quantum
emitters. QFC is implemented by combining single photons from an InAs quantum
dot (QD) at 980 nm with a 1550 nm pump laser in a periodically-poled lithium
niobate (PPLN) waveguide to generate photons at 600 nm with a
signal-to-background ratio exceeding 100:1. Photon correlation and two-photon
interference measurements confirm that both the single photon character and
wavepacket interference of individual QD states are preserved during frequency
conversion. Finally, we convert two spectrally separate QD transitions to the
same wavelength in a single PPLN waveguide and show that the resulting field
exhibits non-classical two-photon interference.Comment: Supercedes arXiv:1205.221
Simultaneous Wavelength Translation and Amplitude Modulation of Single Photons from a Quantum Dot
Hybrid quantum information devices that combine disparate physical systems
interacting through photons offer the promise of combining low-loss
telecommunications wavelength transmission with high fidelity visible
wavelength storage and manipulation. The realization of such systems requires
control over the waveform of single photons to achieve spectral and temporal
matching. Here, we experimentally demonstrate the simultaneous wavelength
translation and amplitude modulation of single photons generated by a quantum
dot emitting near 1300 nm with an exponentially-decaying waveform (lifetime
1.5 ns). Quasi-phase-matched sum-frequency generation with a pulsed
1550 nm laser creates single photons at 710 nm with a controlled amplitude
modulation at 350 ps timescales.Comment: 5 pages, 4 figure
Frequency control of photonic crystal membrane resonators by mono-layer deposition
We study the response of GaAs photonic crystal membrane resonators to thin
film deposition. Slow spectral shifts of the cavity mode of several nanometers
are observed at low temperatures, caused by cryo-gettering of background
molecules. Heating the membrane resets the drift and shielding will prevent
drift altogether. In order to explore the drift as a tool to detect surface
layers, or to intentionally shift the cavity resonance frequency, we studied
the effect of self-assembled monolayers of polypeptide molecules attached to
the membranes. The 2 nm thick monolayers lead to a discrete step in the
resonance frequency and partially passivate the surface.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let