3,199 research outputs found
Correspondence from H. Metcalf to General Hodsdon
Correspondence from H. Metcalf regarding absent soldiers from Lincoln Count
Correspondence from H. Metcalf to General Hodsdon
Correspondence from H. Metcalf regarding absent soldiers from Lincoln Count
Reply to letter from W.H. Stevens, August 12, 1940.
https://digitalmaine.com/alien_corresp/1022/thumbnail.jp
Initializing a Quantum Register from Mott Insulator States in Optical Lattices
We propose and quantitatively develop two schemes to quickly and accurately
generate a stable initial configuration of neutral atoms in optical microtraps
by extraction from the Mott insulator state in optical lattices. We show that
thousands of atoms may be extracted and stored in the ground states of optical
microtrap arrays with one atom per trap in one operational process
demonstrating massive scalability. The failure probability during extraction in
the first scheme can be made sufficiently small (10^{-4}) to initialize a large
scale quantum register with high fidelity. A complementary faster scheme with
more extracted atoms but lower fidelity is also developed.Comment: 5 pages, 3 figure
Anisotropic sub-Doppler laser cooling in dysprosium magneto-optical traps
Magneto-optical traps (MOTs) of Er and Dy have recently been shown to exhibit
population-wide sub-Doppler cooling due to their near degeneracy of excited and
ground state Lande g factors. We discuss here an additional, unusual intra-MOT
sub-Doppler cooling mechanism that appears when the total Dy MOT cooling laser
intensity and magnetic quadrupole gradient increase beyond critical values.
Specifically, anisotropically sub-Doppler-cooled cores appear, and their
orientation with respect to the quadrupole axis flips at a critical ratio of
the MOT laser intensity along the quadrupole axis versus that in the plane of
symmetry. This phenomenon can be traced to a loss of the velocity-selective
resonance at zero velocity in the cooling force along directions in which the
atomic polarization is oriented by the quadrupole field. We present data
characterizing this anisotropic laser cooling phenomenon and discuss a
qualitative model for its origin based on the extraordinarily large Dy magnetic
moment and Dy's near degenerate g factors.Comment: 4 pages, 5 figure
Continuous Loading of a Conservative Trap from an Atomic Beam
We demonstrate the fast accumulation of Cr atoms in a conservative potential
from a magnetically guided atomic beam. Without laser cooling on a cycling
transition, a single dissipative step realized by optical pumping allows to
load atoms at a rate of 2*10^7 1/s in the trap. Within less than 100 ms we
reach the collisionally dense regime, from which we directly produce a
Bose-Einstein condensate with subsequent evaporative cooling. This constitutes
a new approach to degeneracy where, provided a slow beam of particles can be
produced by some means, Bose-Einstein condensation can be reached for species
without a cycling transition.Comment: 4 pages, 4 figure
Laser Phase and Frequency Stabilization Using Atomic Coherence
We present a novel and simple method of stabilizing the laser phase and
frequency by polarization spectroscopy of an atomic vapor. In analogy to the
Pound-Drever-Hall method, which uses a cavity as a memory of the laser phase,
this method uses atomic coherence (dipole oscillations) as a phase memory of
the transmitting laser field. A preliminary experiment using a distributed
feedback laser diode and a rubidium vapor cell demonstrates a
shot-noise-limited laser linewidth reduction (from 2 MHz to 20 kHz). This
method would improve the performance of gas-cell-based optical atomic clocks
and magnetometers and facilitate laser-cooling experiments using narrow
transitions.Comment: 7 pages, 6 figures, appendix on the derivation of Eq.(3) (transfer
function for a polarization-spectroscopy-based frequency discriminator) has
been adde
Mixing of ultracold atomic clouds by merging of two magnetic traps
We demonstrate a method to make mixtures of ultracold atoms that does not
make use of a two-species magneto-optical trap. We prepare two clouds of 87Rb
atoms in distinct magnetic quadrupole traps and mix the two clouds by merging
the traps. For correctly chosen parameters the mixing can be done essentially
without loss of atoms and with only minor heating. The basic features of the
process can be accounted for by a classical simulation of particle
trajectories. Such calculations indicate that mixing of different mass species
is also feasible, opening the way for using the method as a starting point for
making quantum gas mixtures.Comment: 12 pages, 13 figures. Fig. 10 corrected. Fig. 13 updated with more
points and better statistics. A couple of paragraphs rephrased and typos
corrected. References update
Probing -Spin Correlations in Optical Lattices
We propose a technique to measure multi-spin correlation functions of
arbitrary range as determined by the ground states of spinful cold atoms in
optical lattices. We show that an observation of the atomic version of the
Stokes parameters, using focused lasers and microwave pulsing, can be related
to -spin correlators. We discuss the possibility of detecting not only
ground state static spin correlations, but also time-dependent spin wave
dynamics as a demonstrative example using our proposed technique.Comment: 7 pages, 4 figure
Doppler-free Yb Spectroscopy with Fluorescence Spot Technique
We demonstrate a simple technique to measure the resonant frequency of the
398.9 nm 1S0 - 1P1 transition for the different Yb isotopes. The technique,
that works by observing and aligning fluorescence spots, has enabled us to
measure transition frequencies and isotope shifts with an accuracy of 60 MHz.
We provide wavelength measurements for the transition that differ from
previously published work. Our technique also allows for the determination of
Doppler shifted transition frequencies for photoionisation experiments when the
atomic beam and laser beam are not perpendicular and furthermore allows us to
determine the average velocity of the atoms along the direction of atomic beam
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