10 research outputs found
Generation and purification of maximally-entangled atomic states in optical cavities
We present a probabilistic scheme for generating and purifying
maximally-entangled states of two atoms inside an optical cavity via no-photon
detection in the output cavity mode, where ideal detectors may not be required.
The intermediate mixed states can be continuously "filtered" so as to violate
Bell inequalities in a parametrized manner. The scheme relies on an additional
strong-driving field that yields unusual dynamics in cavity QED experiments,
simultaneously realizing Jaynes-Cummings and anti-Jaynes-Cummings interactions.Comment: 4 pages and 3 figure
Instantaneous Measurement of field quadrature moments and entanglement
We present a method of measuring expectation values of quadrature moments of
a multimode field through two-level probe ``homodyning''. Our approach is based
on an integral transform formalism of measurable probe observables, where
analytically derived kernels unravel efficiently the required field information
at zero interaction time, minimizing decoherence effects. The proposed scheme
is suitable for fields that, while inaccessible to a direct measurement, enjoy
one and two-photon Jaynes-Cummings interactions with a two-level probe, like
spin, phonon, or cavity fields. Available data from previous experiments are
used to confirm our predictions.Comment: 4 pages, no figures, modified version with experimental estimation
Measure of phonon-number moments and motional quadratures through infinitesimal-time probing of trapped ions
A method for gaining information about the phonon-number moments and the
generalized nonlinear and linear quadratures in the motion of trapped ions (in
particular, position and momentum) is proposed, valid inside and outside the
Lamb-Dicke regime. It is based on the measurement of first time derivatives of
electronic populations, evaluated at the motion-probe interaction time t=0. In
contrast to other state-reconstruction proposals, based on measuring Rabi
oscillations or dispersive interactions, the present scheme can be performed
resonantly at infinitesimal short motion-probe interaction times, remaining
thus insensitive to decoherence processes.Comment: 10 pages. Accepted in JPhys
Fresnel Representation of the Wigner Function: An Operational Approach
We present an operational definition of the Wigner function. Our method
relies on the Fresnel transform of measured Rabi oscillations and applies to
motional states of trapped atoms as well as to field states in cavities. We
illustrate this technique using data from recent experiments in ion traps [D.
M. Meekhof et al., Phys. Rev. Lett. 76, 1796 (1996)] and in cavity QED [B.
Varcoe et al., Nature 403, 743 (2000)]. The values of the Wigner functions of
the underlying states at the origin of phase space are W(0)=+1.75 for the
vibrational ground state and W(0)=-1.4 for the one-photon number state. We
generalize this method to wave packets in arbitrary potentials.Comment: 4 pages include 4 figures, submitted to PR
Solvable model of a strongly-driven micromaser
We study the dynamics of a micromaser where the pumping atoms are strongly
driven by a resonant classical field during their transit through the cavity
mode. We derive a master equation for this strongly-driven micromaser,
involving the contributions of the unitary atom-field interactions and the
dissipative effects of a thermal bath. We find analytical solutions for the
temporal evolution and the steady-state of this system by means of phase-space
techniques, providing an unusual solvable model of an open quantum system,
including pumping and decoherence. We derive closed expressions for all
relevant expectation values, describing the statistics of the cavity field and
the detected atomic levels. The transient regime shows the build-up of mixtures
of mesoscopic fields evolving towards a superpoissonian steady-state field
that, nevertheless, yields atomic correlations that exhibit stronger
nonclassical features than the conventional micromaser.Comment: 9 pages, 16 figures. Submitted for publicatio
Solvable model of dissipative dynamics in the deep strong coupling regime
We describe the dynamics of a qubit interacting with a bosonic mode coupled
to a zero-temperature bath in the deep strong coupling (DSC) regime. We provide
an analytical solution for this open system dynamics in the off-resonance case
of the qubit-mode interaction. Collapses and revivals of parity chain
populations and the oscillatory behavior of the mean photon number are
predicted. At the same time, photon number wave packets, propagating back and
forth along parity chains, become incoherently mixed. Finally, we investigate
numerically the effect of detuning on the validity of the analytical solution.Comment: 6 pages, 8 figure