487 research outputs found
Using time reversal symmetry for sensitive incoherent matter-wave Sagnac interferometry
We present a theory of the transmission of incoherent guided matter-waves
through Sagnac interferometers. Interferometer configurations with only one
input and one output port have a property similar to the phase rigidity
observed in the transmission through Aharonov-Bohm interferometers in coherent
mesoscopic electronics. This property is connected to the existence of
counterpropagating paths of equal length and enables the operation of such
matter-wave interferometers with incoherent sources. High finesse
interferometers of this kind have a rotation sensitivity inversely proportional
to the square root of the finesse
Dynamic Matter-Wave Pulse Shaping
In this paper we discuss possibilities to manipulate a matter-wave with
time-dependent potentials. Assuming a specific setup on an atom chip, we
explore how one can focus, accelerate, reflect, and stop an atomic wave packet,
with, for example, electric fields from an array of electrodes. We also utilize
this method to initiate coherent splitting. Special emphasis is put on the
robustness of the control schemes. We begin with the wave packet of a single
atom, and extend this to a BEC, in the Gross-Pitaevskii picture. In analogy to
laser pulse shaping with its wide variety of applications, we expect this work
to form the base for additional time-dependent potentials eventually leading to
matter-wave pulse shaping with numerous application
Coupling between internal spin dynamics and external degrees of freedom in the presence of colored noise
We observe asymmetric transition rates between Zeeman levels (spin-flips) of
magnetically trapped atoms. The asymmetry strongly depends on the spectral
shape of an applied noise. This effect follows from the interplay between the
internal states of the atoms and their external degrees of freedom, where
different trapped levels experience different potentials. Such insight may
prove useful for controlling atomic states by the introduction of noise, as
well as provide a better understanding of the effect of noise on the coherent
operation of quantum systems.Comment: 5 pages, 4 figures; accepted to PR
One-mirror Fabry-Perot and one-slit Young interferometry
We describe a new and distinctive interferometry in which a probe particle
scatters off a superposition of locations of a single free target particle. In
one dimension, probe particles incident on superposed locations of a single
"mirror" can interfere as if in a Fabry-Perot interferometer; in two
dimensions, probe particles scattering off superposed locations of a single
"slit" can interfere as if in a two-slit Young interferometer. The condition
for interference is loss of orthogonality of the target states and reduces, in
simple examples, to transfer of orthogonality from target to probe states. We
analyze experimental parameters and conditions necessary for interference to be
observed.Comment: 5 pages, 2 figures, RevTeX, submitted to PR
Organized Current Patterns in Disordered Conductors
We present a general theory of current deviations in straight current
carrying wires with random imperfections, which quantitatively explains the
recent observations of organized patterns of magnetic field corrugations above
micron-scale evaporated wires. These patterns originate from the most efficient
electron scattering by Fourier components of the wire imperfections with
wavefronts along the direction. We show that long range
effects of surface or bulk corrugations are suppressed for narrow wires or
wires having an electrically anisotropic resistivity
Diffraction of a Bose-Einstein Condensate in the Time Domain
We have observed the diffraction of a Bose-Einstein condensate of rubidium
atoms on a vibrating mirror potential. The matter wave packet bounces back at
normal incidence on a blue-detuned evanescent light field after a 3.6 mm free
fall. The mirror vibrates at a frequency of 500 kHz with an amplitude of 3.0
nm. The atomic carrier and sidebands are directly imaged during their ballistic
expansion. The locations and the relative weights of the diffracted atomic wave
packets are in very good agreement with the theoretical prediction of Carsten
Henkel et al. [1].Comment: submitted to Phys. Rev.
Trapping cold atoms using surface-grown carbon nanotubes
We present a feasibility study for loading cold atomic clouds into magnetic
traps created by single-wall carbon nanotubes grown directly onto dielectric
surfaces. We show that atoms may be captured for experimentally sustainable
nanotube currents, generating trapped clouds whose densities and lifetimes are
sufficient to enable detection by simple imaging methods. This opens the way
for a novel type of conductor to be used in atomchips, enabling atom trapping
at sub-micron distances, with implications for both fundamental studies and for
technological applications
Pregnancy rates of dairy cows at first service: influence of gonadotropin-releasing hormone and timing of AI relative to estrus
The 1989 Annual KSU Dairy Day is known as Dairy Day, 1989We demonstrated that gonadotropin-releasing hormone (GnRH or Cystorelin®) failed to
improve pregnancy rates at the first service. When GnRH injection and insemination are both carried
out either in early or late estrus or if cows are bred in early estrus and given a GnRH injection later in
estrus, pregnancy rates are reduced by 9 to 13 percentage points compared to breeding according to the
am-pm rule without GnRH treatment (control). Pregnancy rates of cows injected with GnRH early in
estrus and bred in late estrus were similar to controls injected with saline and inseminated late in estrus
(46 vs 43%). Altering the time of breeding and the time of GnRH injection to either early or late estrus
did not improve pregnancy rates. We continue to recommend using GnRH only for repeat breeders,
because GnRH consistently improves pregnancy rates at 3rd or 4th service, but not at first services
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