1,261 research outputs found
Mechanical effects of optical resonators on driven trapped atoms: Ground state cooling in a high finesse cavity
We investigate theoretically the mechanical effects of light on atoms trapped
by an external potential, whose dipole transition couples to the mode of an
optical resonator and is driven by a laser. We derive an analytical expression
for the quantum center-of-mass dynamics, which is valid in presence of a tight
external potential. This equation has broad validity and allows for a
transparent interpretation of the individual scattering processes leading to
cooling. We show that the dynamics are a competition of the mechanical effects
of the cavity and of the laser photons, which may mutually interfere. We focus
onto the good-cavity limit and identify novel cooling schemes, which are based
on quantum interference effects and lead to efficient ground state cooling in
experimentally accessible parameter regimes.Comment: 17 pages, 6 figure
Strategies for Collecting Data in Physical Education
It is important to collect accurate data on student performance in order to be accountable for the instruction and learning of students. Although barriers sometimes impede data collection, they can be overcome through strategies such as (a) planning, (b) matching collection strategies to the setting, (c) recording your own behavior, (d) using specific rubrics, (e) collecting data on one or two students a day, (f) training and directing paraeducators, (g) teaching students to self monitor, and (h) utilizing simple equipment to record data. Once accurate and sufficient data is collected, placements, planning, modifications, instruction, and feedback are easier, more valid, and effective
Strategies for Collecting Data in Physical Education
It is important to collect accurate data on student performance in order to be accountable for the instruction and learning of students. Although barriers sometimes impede data collection, they can be overcome through strategies such as (a) planning, (b) matching collection strategies to the setting, (c) recording your own behavior, (d) using specific rubrics, (e) collecting data on one or two students a day, (f) training and directing paraeducators, (g) teaching students to self monitor, and (h) utilizing simple equipment to record data. Once accurate and sufficient data is collected, placements, planning, modifications, instruction, and feedback are easier, more valid, and effective
Single-Photon Generation from Stored Excitation in an Atomic Ensemble
Single photons are generated from an ensemble of cold Cs atoms via the
protocol of Duan et al. [Nature \textbf{414}, 413 (2001)]. Conditioned upon an
initial detection from field 1 at 852 nm, a photon in field 2 at 894 nm is
produced in a controlled fashion from excitation stored within the atomic
ensemble. The single-quantum character of the field 2 is demonstrated by the
violation of a Cauchy-Schwarz inequality, namely , where describes detection of two events
conditioned upon an initial detection , with
for single photons.Comment: 5 pages, 4 figure
Single Atom Detection With Optical Cavities
We present a thorough analysis of single atom detection using optical
cavities. The large set of parameters that influence the signal-to-noise ratio
for cavity detection is considered, with an emphasis on detunings, probe power,
cavity finesse and photon detection schemes. Real device operating restrictions
for single photon counting modules and standard photodiodes are included in our
discussion, with heterodyne detection emerging as the clearly favourable
technique, particularly for detuned detection at high power.Comment: 11 pages, 8 figures, submitted to PRA, minor changes in Secs. I and
IVD.2, and revised Fig.
Cavity optomechanics with stoichiometric SiN films
We study high-stress SiN films for reaching the quantum regime with
mesoscopic oscillators connected to a room-temperature thermal bath, for which
there are stringent requirements on the oscillators' quality factors and
frequencies. Our SiN films support mechanical modes with unprecedented products
of mechanical quality factor and frequency reaching Hz. The SiN membranes exhibit a low optical absorption
characterized by Im at 935 nm, representing a 15 times
reduction for SiN membranes. We have developed an apparatus to simultaneously
cool the motion of multiple mechanical modes based on a short, high-finesse
Fabry-Perot cavity and present initial cooling results along with future
possibilities.Comment: 4 pages, 5 figure
Robust quantum gates on neutral atoms with cavity-assisted photon-scattering
We propose a scheme to achieve quantum computation with neutral atoms whose
interactions are catalyzed by single photons. Conditional quantum gates,
including an -atom Toffoli gate and nonlocal gates on remote atoms, are
obtained through cavity-assisted photon scattering in a manner that is robust
to random variation in the atom-photon coupling rate and which does not require
localization in the Lamb-Dicke regime. The dominant noise in our scheme is
automatically detected for each gate operation, leading to signalled errors
which do not preclude efficient quantum computation even if the error
probability is close to the unity.Comment: 4 pages, 3 figure
Coupling of Light and Mechanics in a Photonic Crystal Waveguide
Observations of thermally driven transverse vibration of a photonic crystal
waveguide (PCW) are reported. The PCW consists of two parallel nanobeams with a
240 nm vacuum gap between the beams. Models are developed and validated for the
transduction of beam motion to phase and amplitude modulation of a weak optical
probe propagating in a guided mode (GM) of the PCW for probe frequencies far
from and near to the dielectric band edge. Since our PCW has been designed for
near-field atom trapping, this research provides a foundation for evaluating
possible deleterious effects of thermal motion on optical atomic traps near the
surfaces of PCWs. Longer term goals are to achieve strong atom-mediated links
between individual phonons of vibration and single photons propagating in the
GMs of the PCW, thereby enabling opto-mechanics at the quantum level with
atoms, photons, and phonons. The experiments and models reported here provide a
basis for assessing such goals, including sensing mechanical motion at the
Standard Quantum Limit (SQL).Comment: 13 pages, 13 figure
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