1,583 research outputs found
Cavity QED with optically transported atoms
Ultracold Rb atoms are delivered into a high-finesse optical
micro-cavity using a translating optical lattice trap and detected via the
cavity field. The atoms are loaded into an optical lattice from a magneto-optic
trap (MOT) and transported 1.5 cm into the cavity. Our cavity satisfies the
strong-coupling requirements for a single intracavity atom, thus permitting
real-time observation of single atoms transported into the cavity. This
transport scheme enables us to vary the number of intracavity atoms from 1 to
100 corresponding to a maximum atomic cooperativity parameter of 5400, the
highest value ever achieved in an atom--cavity system. When many atoms are
loaded into the cavity, optical bistability is directly measured in real-time
cavity transmission.Comment: 4 figures, 4 page
Real-Time Cavity QED with Single Atoms
The combination of cold atoms and large coherent coupling enables investigations in a new regime in cavity QED with single-atom trajectories monitored in real time with high signal-to-noise ratio. The underlying âvacuum-Rabiâ splitting is clearly reflected in the frequency dependence of atomic transit signals recorded atom by atom, with evidence for mechanical light forces for intracavity photon number <1. The nonlinear optical response of one atom in a cavity is observed to be in accord with the one-atom quantum theory but at variance with semiclassical predictions
Cavity QED with Multiple Hyperfine Levels
We calculate the weak-driving transmission of a linearly polarized cavity
mode strongly coupled to the D2 transition of a single Cesium atom. Results are
relevant to future experiments with microtoroid cavities, where the
single-photon Rabi frequency g exceeds the excited-state hyperfine splittings,
and photonic bandgap resonators, where g is greater than both the excited- and
ground-state splitting.Comment: 6 pages, 10 figure
Real-time detection of individual atoms falling through a high-finesse optical cavity
The enhanced coupling between atoms and photons inside a high-finesse optical cavity provides a novel basis for optical measurements that continuously monitor atomic degrees of freedom. We describe an experiment in which cavity quantum-electrodynamic effects are utilized for real-time detection of individual atoms falling through an optical cavity after being dropped from a magneto-optical trap. Our technique permits experiments that are triggered by the presence of a single optimally coupled atom within the cavity mode volume
Real-time cavity QED with single atoms
We report the first measurement of the real-time evolution of the complex field amplitude brought on by single atom transits. We show the variation in time of both quadrature amplitudes (simultaneously recorded) of the light transmitted through the cavity, as well the resultant optical phase for a single atom transit event. In this particular measurement, the cavity and laser were both detuned by 10 MHz from the Cs resonance
Mach-Zehnder Interferometry at the Heisenberg Limit with coherent and squeezed-vacuum light
We show that the phase sensitivity of a Mach-Zehnder
interferometer fed by a coherent state in one input port and squeezed-vacuum in
the other one is i) independent from the true value of the phase shift and ii)
can reach the Heisenberg limit , where is the
average number of particles of the input states. We also show that the
Cramer-Rao lower bound, , can be saturated for arbitrary values of the squeezing parameter
and the amplitude of the coherent mode by a Bayesian phase
inference protocol.Comment: 4 pages, 4 figure
Entanglement generated between a single atom and a laser pulse
We quantify the entanglement generated between an atom and a laser pulse in
free space. We find that the entanglement calculated using a simple
closed-system Jaynes-Cummings Hamiltonian is in remarkable agreement with a
full open-system calculation, even though the free-space geometry is far from
the strong coupling regime of cavity QED. We explain this result using a simple
model in which the atom couples weakly to the laser while coupling strongly to
the vacuum. Additionally we place an upper bound on the total entanglement
between the atom and all paraxial modes using a quantum trajectories
unravelling. This upper bound provides a benchmark for atom-laser coupling.Comment: 8 pages, 4 figure
Clocked Atom Delivery to a Photonic Crystal Waveguide
Experiments and numerical simulations are described that develop quantitative
understanding of atomic motion near the surfaces of nanoscopic photonic crystal
waveguides (PCWs). Ultracold atoms are delivered from a moving optical lattice
into the PCW. Synchronous with the moving lattice, transmission spectra for a
guided-mode probe field are recorded as functions of lattice transport time and
frequency detuning of the probe beam. By way of measurements such as these, we
have been able to validate quantitatively our numerical simulations, which are
based upon detailed understanding of atomic trajectories that pass around and
through nanoscopic regions of the PCW under the influence of optical and
surface forces. The resolution for mapping atomic motion is roughly 50 nm in
space and 100 ns in time. By introducing auxiliary guided mode (GM) fields that
provide spatially varying AC-Stark shifts, we have, to some degree, begun to
control atomic trajectories, such as to enhance the flux into to the central
vacuum gap of the PCW at predetermined times and with known AC-Stark shifts.
Applications of these capabilities include enabling high fractional filling of
optical trap sites within PCWs, calibration of optical fields within PCWs, and
utilization of the time-dependent, optically dense atomic medium for novel
nonlinear optical experiments
Entanglement of Pure Two-Mode Gaussian States
The entanglement of general pure Gaussian two-mode states is examined in
terms of the coefficients of the quadrature components of the wavefunction. The
entanglement criterion and the entanglement of formation are directly evaluated
as a function of these coefficients, without the need for deriving local
unitary transformations. These reproduce the results of other methods for the
special case of symmetric pure states which employ a relation between squeezed
states and Einstein-Podolsky-Rosen correlations. The modification of the
quadrature coefficients and the corresponding entanglement due to application
of various optical elements is also derived.Comment: 12 page
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