1,841 research outputs found
Producing Bose condensates using optical lattices
We relate the entropies of ensembles of atoms in optical lattices to atoms in
simple traps. We then determine which ensembles of lattice-bound atoms will
adiabatically transform into a Bose condensate. This shows a feasible approach
to Bose condensation without evaporative cooling.Comment: RevTeX, 5 pages, 5 eps-figure
Recoil-free spectroscopy of neutral Sr atoms in the Lamb-Dicke regime
We have demonstrated a recoil-free spectroscopy on the
transition of strontium atoms confined in a one-dimensional optical lattice. By
investigating the wavelength and polarization dependence of the ac Stark shift
acting on the and states, we determined the {\it
magic wavelength} where the Stark shifts for both states coincide. The
Lamb-Dicke confinement provided by this Stark-free optical lattice enabled the
measurement of the atomic spectrum free from Doppler as well as recoil shifts.Comment: 5pages, 4figure
Phase-sensitive detection of Bragg scattering at 1D optical lattices
We report on the observation of Bragg scattering at 1D atomic lattices. Cold
atoms are confined by optical dipole forces at the antinodes of a standing wave
generated by the two counter-propagating modes of a laser-driven high-finesse
ring cavity. By heterodyning the Bragg-scattered light with a reference beam,
we obtain detailed information on phase shifts imparted by the Bragg scattering
process. Being deep in the Lamb-Dicke regime, the scattered light is not
broadened by the motion of individual atoms. In contrast, we have detected
signatures of global translatory motion of the atomic grating.Comment: 4 pages, 4 figure
Bloch Structures in a Rotating Bose-Einstein Condensate
A rotating Bose-Einstein condensate is shown to exhibit a Bloch band
structure without the need of periodic potential. Vortices enter the condensate
by a mechanism similar to the Bragg reflection, if the frequency of a rotating
drive or the strength of interaction is adiabatically changed. A localized
state analogous to a gap soliton in a periodic system is predicted near the
edge of the Brillouin zone.Comment: 4 pages, 3 figure
A lattice of double wells for manipulating pairs of cold atoms
We describe the design and implementation of a 2D optical lattice of double
wells suitable for isolating and manipulating an array of individual pairs of
atoms in an optical lattice. Atoms in the square lattice can be placed in a
double well with any of their four nearest neighbors. The properties of the
double well (the barrier height and relative energy offset of the paired sites)
can be dynamically controlled. The topology of the lattice is phase stable
against phase noise imparted by vibrational noise on mirrors. We demonstrate
the dynamic control of the lattice by showing the coherent splitting of atoms
from single wells into double wells and observing the resulting double-slit
atom diffraction pattern. This lattice can be used to test controlled neutral
atom motion among lattice sites and should allow for testing controlled
two-qubit gates.Comment: 9 pages, 11 figures Accepted for publication in Physical Review
Experimental study of optimal measurements for quantum state tomography
Quantum tomography is a critically important tool to evaluate quantum
hardware, making it essential to develop optimized measurement strategies that
are both accurate and efficient. We compare a variety of strategies using
nearly pure test states. Those that are informationally complete for all states
are found to be accurate and reliable even in the presence of errors in the
measurements themselves, while those designed to be complete only for pure
states are far more efficient but highly sensitive to such errors. Our results
highlight the unavoidable tradeoffs inherent to quantum tomography.Comment: 5 pages, 3 figure
Spectroscopy of the Clock Transition of Sr in an Optical Lattice
We report on the spectroscopy of the clock transition of atoms (natural linewidth of 1
mHz) trapped in a one-dimensional optical lattice. Recoilless transitions with
a linewidth of 0.7 kHz as well as the vibrational structure of the lattice
potential were observed. By investigating the wavelength dependence of the
carrier linewidth, we determined the magic wavelength, where the light shift in
the clock transition vanishes, to be nm.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Lett. (09/May/2003
Manipulation of Single Neutral Atoms in Optical Lattices
We analyze a scheme to manipulate quantum states of neutral atoms at
individual sites of optical lattices using focused laser beams. Spatial
distributions of focused laser intensities induce position-dependent energy
shifts of hyperfine states, which, combined with microwave radiation, allow
selective manipulation of quantum states of individual target atoms. We show
that various errors in the manipulation process are suppressed below
with properly chosen microwave pulse sequences and laser parameters. A similar
idea is also applied to measure quantum states of single atoms in optical
lattices.Comment: 5 pages, 3 figure
Quantum computing with spatially delocalized qubits
We analyze the operation of quantum gates for neutral atoms with qubits that
are delocalized in space, i.e., the computational basis states are defined by
the presence of a neutral atom in the ground state of one out of two trapping
potentials. The implementation of single qubit gates as well as a controlled
phase gate between two qubits is discussed and explicit calculations are
presented for rubidium atoms in optical microtraps. Furthermore, we show how
multi-qubit highly entangled states can be created in this scheme.Comment: 4 pages, 4 figure
- …