666 research outputs found
Cavity QED with Single Atoms and Photons
Recent experimental advances in the field of cavity quantum electrodynamics (QED) have opened new possibilities for control of atom-photon interactions. A laser with "one and the same atom" demonstrates the theory of laser operation pressed to its conceptual limit. The generation of single photons on demand and the realization of cavity QED with well defined atomic numbers N = 0, 1, 2,... both represent important steps toward realizing diverse protocols in quantum information science. Coherent manipulation of the atomic state via Raman transitions provides a new tool in cavity QED for in situ monitoring and control of the atom-cavity system. All of these achievements share a common point of departure: the regime of strong coupling. It is thus interesting to consider briefly the history of the strong coupling criterion in cavity QED and to trace out the path that research has taken in the pursuit of this goal
Dynamics of a tunable superfluid junction
We study the population dynamics of a Bose-Einstein condensate in a
double-well potential throughout the crossover from Josephson dynamics to
hydrodynamics. At barriers higher than the chemical potential, we observe slow
oscillations well described by a Josephson model. In the limit of low barriers,
the fundamental frequency agrees with a simple hydrodynamic model, but we also
observe a second, higher frequency. A full numerical simulation of the
Gross-Pitaevskii equation giving the frequencies and amplitudes of the observed
modes between these two limits is compared to the data and is used to
understand the origin of the higher mode. Implications for trapped matter-wave
interferometers are discussed.Comment: 8 pages, 7 figures; v3: Journal reference added, minor changes to
tex
Observation of the Vacuum-Rabi Spectrum for One Trapped Atom
The transmission spectrum for one atom strongly coupled to the field of a
high-finesse optical resonator is observed to exhibit a clearly resolved
vacuum-Rabi splitting characteristic of the normal modes in the eigenvalue
spectrum of the atom-cavity system. A new Raman scheme for cooling atomic
motion along the cavity axis enables a complete spectrum to be recorded for an
individual atom trapped within the cavity mode, in contrast to all previous
measurements in cavity QED that have required averaging over many atoms.Comment: 5 pages with 4 figure
Electromagnetic Radiation Hardness of Diamond Detectors
The behavior of artificially grown CVD diamond films under intense
electromagnetic radiation has been studied. The properties of irradiated
diamond samples have been investigated using the method of thermally stimulated
current and by studying their charge collection properties. Diamonds have been
found to remain unaffected after doses of 6.8 MGy of 10 keV photons and 10 MGy
of MeV-range photons. This observation makes diamond an attractive detector
material for a calorimeter in the very forward region of the proposed TESLA
detector.Comment: 19 pages, 9 figure
Cystic Cervical Intramedullary Ependymoma with Previous lntracyst Hemorrhage: Magnetic Resonance Imaging at 1.5 T
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117483/1/jon199442111.pd
Optical Phonon Lasing in Semiconductor Double Quantum Dots
We propose optical phonon lasing for a double quantum dot (DQD) fabricated in
a semiconductor substrate. We show that the DQD is weakly coupled to only two
LO phonon modes that act as a natural cavity. The lasing occurs for pumping the
DQD via electronic tunneling at rates much higher than the phonon decay rate,
whereas an antibunching of phonon emission is observed in the opposite regime
of slow tunneling. Both effects disappear with an effective thermalization
induced by the Franck-Condon effect in a DQD fabricated in a carbon nanotube
with a strong electron-phonon coupling.Comment: 8 pages, 4 figure
Shaping the Phase of a Single Photon
While the phase of a coherent light field can be precisely known, the phase
of the individual photons that create this field, considered individually,
cannot. Phase changes within single-photon wave packets, however, have
observable effects. In fact, actively controlling the phase of individual
photons has been identified as a powerful resource for quantum communication
protocols. Here we demonstrate the arbitrary phase control of a single photon.
The phase modulation is applied without affecting the photon's amplitude
profile and is verified via a two-photon quantum interference measurement,
which can result in the fermionic spatial behaviour of photon pairs. Combined
with previously demonstrated control of a single photon's amplitude, frequency,
and polarisation, the fully deterministic phase shaping presented here allows
for the complete control of single-photon wave packets.Comment: 4 pages, 4 figure
Theory of Photon Blockade by an Optical Cavity with One Trapped Atom
In our recent paper [1], we reported observations of photon blockade by one
atom strongly coupled to an optical cavity. In support of these measurements,
here we provide an expanded discussion of the general phenomenology of photon
blockade as well as of the theoretical model and results that were presented in
Ref. [1]. We describe the general condition for photon blockade in terms of the
transmission coefficients for photon number states. For the atom-cavity system
of Ref. [1], we present the model Hamiltonian and examine the relationship of
the eigenvalues to the predicted intensity correlation function. We explore the
effect of different driving mechanisms on the photon statistics. We also
present additional corrections to the model to describe cavity birefringence
and ac-Stark shifts. [1] K. M. Birnbaum, A. Boca, R. Miller, A. D. Boozer, T.
E. Northup, and H. J. Kimble, Nature 436, 87 (2005).Comment: 10 pages, 6 figure
Vacuum-stimulated cooling of single atoms in three dimensions
Taming quantum dynamical processes is the key to novel applications of
quantum physics, e.g. in quantum information science. The control of
light-matter interactions at the single-atom and single-photon level can be
achieved in cavity quantum electrodynamics, in particular in the regime of
strong coupling where atom and cavity form a single entity. In the optical
domain, this requires permanent trapping and cooling of an atom in a
micro-cavity. We have now realized three-dimensional cavity cooling and
trapping for an orthogonal arrangement of cooling laser, trap laser and cavity
vacuum. This leads to average single-atom trapping times exceeding 15 seconds,
unprecedented for a strongly coupled atom under permanent observation.Comment: 4 pages, 4 figure
State-Insensitive Cooling and Trapping of Single Atoms in an Optical Cavity
Single Cesium atoms are cooled and trapped inside a small optical cavity by
way of a novel far-off-resonance dipole-force trap (FORT), with observed
lifetimes of 2 to 3 seconds. Trapped atoms are observed continuously via
transmission of a strongly coupled probe beam, with individual events lasting ~
1 s. The loss of successive atoms from the trap N = 3 -> 2 -> 1 -> 0 is thereby
monitored in real time. Trapping, cooling, and interactions with strong
coupling are enabled by the FORT potential, for which the center-of-mass motion
is only weakly dependent on the atom's internal state.Comment: 5 pages, 4 figures Revised version to appear in Phys. Rev. Let
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