90 research outputs found
Atomic Interferometer with Amplitude Gratings of Light and its Applications to Atom Based Tests of the Equivalence Principle
We have developed a matter wave interferometer based on the diffraction of
atoms from effective absorption gratings of light. In a setup with cold
rubidium atoms in an atomic fountain the interferometer has been used to carry
out tests of the equivalence principle on an atomic basis. The gravitational
acceleration of the two isotopes 85Rb and 87Rb was compared, yielding a
difference Dg/g =(1.2 +-1.7)x10^{-7}. We also perform a differential free fall
measurement of atoms in two different hyperfine states, and obtained a result
of Dg/g =(0.4 +-1.2)x10^{-7}.Comment: 4 Pages, 4 figures, accepted for Physical Review Letter
Quantum motion effects in an ultracold-atom Mach-Zehnder interferometer
We study the effect of quantum motion in a Mach-Zehnder interferometer where
ultracold, two-level atoms cross a -- configuration of
separated, laser illuminated regions. Explicit and exact expressions are
obtained for transmission amplitudes of monochromatic, incident atomic waves
using recurrence relations which take into account all possible paths: the
direct ones usually considered in the simple semiclassical treatment, but
including quantum motion corrections, and the paths in which the atoms are
repeatedly reflected at the fields.Comment: 11 pages, 5 figure
Sub-collision hyperfine structure of nonlinear-optical resonance with field scanning
Some experimental evidences for methane are produced that the simple
transition from frequency scanning of nonlinear-optical resonances to magnetic
one may be accompanied with transition from sub-Doppler collisionally broadened
structure to sub-collision hyperfine one. It is conditioned by nonlinearity of
splitting of hyperfine sublevel for molecules in the adiabatically varied
magnetic field and respectively breaking the analogy of magnetic and frequency
scannings. The exact calculation of the resonance structure is considered for
molecules with only one spin subsystem. The approximately spin-additive
calculation of the structure is given for sufficiently fast rotating molecules
with greater number of spin subsystems. Within the same approximation an
example of hyperfine doubling in the magnetic and electric spectra of
nonlinear-optical resonance is considered for fluoromethane.Comment: 56 pages, 10 figures, accepted for publication in J. Mol. Spectrosc
Spontaneous magnetostriction in the Gd-Y system: analysis of phase transformations
The transformations of magnetic and lattice subsystems states of Gd₁₀₀₋xYx (x=0, 5.5, 7.5, 10.2) alloys have been studied at temperatures 5-370 K in magnetic fields up to 4 kOe. The temperature dependences of elastic modules, thermal expansion, low field magnetization and magnetic anisotropy parameters were obtained. The linear spontaneous striction ΔL(T)/L=xh² was analized, and the effective order parameters η and magnetostrictive parameters ξ were evaluated for the four magnetic phases (canted ferromagnetic, deforming ferromagnetic helix, ferromagnetic helix, and the ferromagnetic cone, respectively): ξcf=2.2×10⁻⁵, ξdh=- 5.3×10⁻⁵, ξfh=7.1×10⁻⁵, ξfc=1.4×10⁻³
Atom focusing by far-detuned and resonant standing wave fields: Thin lens regime
The focusing of atoms interacting with both far-detuned and resonant standing
wave fields in the thin lens regime is considered. The thin lens approximation
is discussed quantitatively from a quantum perspective. Exact quantum
expressions for the Fourier components of the density (that include all
spherical aberration) are used to study the focusing numerically. The following
lens parameters and density profiles are calculated as functions of the pulsed
field area : the position of the focal plane, peak atomic density,
atomic density pattern at the focus, focal spot size, depth of focus, and
background density. The lens parameters are compared to asymptotic, analytical
results derived from a scalar diffraction theory for which spherical aberration
is small but non-negligible (). Within the diffraction theory
analytical expressions show that the focused atoms in the far detuned case have
an approximately constant background density
while the peak density behaves as , the focal distance or
time as , the focal spot size as
, and the depth of focus as .
Focusing by the resonant standing wave field leads to a new effect, a Rabi-
like oscillation of the atom density. For the far-detuned lens, chromatic
aberration is studied with the exact Fourier results. Similarly, the
degradation of the focus that results from angular divergence in beams or
thermal velocity distributions in traps is studied quantitatively with the
exact Fourier method and understood analytically using the asymptotic results.
Overall, we show that strong thin lens focusing is possible with modest laser
powers and with currently achievable atomic beam characteristics.Comment: 21 pages, 11 figure
High resolution amplitude and phase gratings in atom optics
An atom-field geometry is chosen in which an atomic beam traverses a field
interaction zone consisting of three fields, one having frequency propagating in the direction and the other two having
frequencies and propagating in the
- direction. For and , where and are positive integers and
is the pulse duration in the atomic rest frame, the atom-field interaction
results in the creation of atom amplitude and phase gratings having period . In this manner, one can use optical fields having
wavelength to produce atom gratings having periodicity much less
than .Comment: 11 pages, 14 figure
OPTICAL TIME SCALE
The production of a time scale based on the use of an oscillation period of a highly stable laser is first reported. The new time standard allows to transfer frequency characteristics of a highly stable laser in the frequency range from 0 to 1014 Hz with no losses in accuracy. Radio-frequency oscillators were synchronized with the aid of fast-response systems of phase offset lock at division of laser frequencies
- …