Quantum Degenerate Gases in Low-Dimensionality
October 4-6, 2004
Brett Esry, Maxim Olshanii, Joerg
Schmiedmayer
Online Workshops
Important Airline Information
Workshop participants who have been promised
stipends and intend to submit their airfare for reimbursement
should be aware of the non-US airline carrier policy which we
must follow and which has been outlined for us by the SAO Travel
Office as follows:
"A visitor, to be reimbursed for his airfare, must have
a ticket which is validated on a United States carrier and lists
the United States carrier code and flight number, even if the
person actually steps onto a non-United States carrier. Here is
an example. United Airlines and Lufthansa are partners. A visitor
must have a ticket which is written on United ticket stock and
lists the United flight numbers even if the person is actually
going onto the Lufthansa plane."
Workshop Participants
|
INVITED SPEAKERS
- Prof Dana Z. Anderson
- JILA
- University of Colorado 440
- Boulder, CO 80309
- dana@jila.colorado.edu
-
- Prof. Doerte Blume
- Department of Physics
- Washington State University
- Pullman, WA 99164-2814
- doerte@wsu.edu
-
- Dr. Michael Bromley
- Kansas State University
- 116 Cardwell Hall
- Manhattan, KS 66506
- bromley@phys.ksu.edu
-
- Dr. Miguel A. Cazalilla
- Donostia Intl Physics Center
- Manuel de Lardizabal, 4
- San Sebastian, E-20018 Spain
- waxcagum@sq.ehu.es
-
- Prof. Eugene Demler
- Physics Department
- Harvard University
- Cambridge, MA 02138
- demler@cmt.harvard.edu
-
- Prof. Brett Esry
- Kansas State University
- Physics Department
- 116 Cardwell Hall
- Manhattan, KS 66502
- esry@phys.ksu.edu
-
- Prof. Tilman Esslinger
- ETH Zurich
- HPF D 4, Hoenggerberg
- Zurich, 8093, Switzerland
- esslinger@phys.ethz.ch
- tilman.esslinger@iqe.phys.ethz.ch
-
- Dr. Chad Fertig
- NIST
- 100 Bureau Drive
- MS 8424
- Gaithersburg, MD 20878
- chad.fertig@nist.gov
-
- Dr. József Fortágh
- University of Tuebingen
- Auf der Morgenstelle 14
- 72076 Tuebingen, Germany
- fortagh@pit.physik.uni-tuebingen.de
-
- Dr. Brian E. Granger
- Santa Clara University
- 500 El Camino Real
- 312 Daly Science
- Santa Clara, CA 95053
- bgranger@scu.edu
-
- Dr. Zoran Hadzibabic
- Laboratoire Kastler Brossel
- Ecole Normale Superieure
- Paris, 75005 France
- Zoran@lkb.ens.fr
-
- Prof. F. Duncan M. Haldane
- Princeton University
- Physics Department
- Jadwin Hall
- Princeton, NJ 08544-0708
- haldane@princeton.edu
-
- Dr. Peter Krüger
- Physikalisches Institut
- University of Heidelberg
- Philosophenweg 12
- 69120 Heidelberg, Germany
- krueger@physi.uni-heidelberg.de
-
- Prof. Elliott H. Lieb
- Princeton University
Jadwin Hall
P.O. Box 708
Princeton, NJ 08544-0708
lieb@princeton.edu
-
- Prof. Michael G. Moore
- Ohio University
- 251 Clippinger Lab
- Department of Physics Astronomy
- Athens, OH 45701
- moorem@ohiou.edu
-
- Dr. Hanns-Christoph Nägerl
- University of Innsbruck
- Technikerstrasse 25/4
- Inst. fuer Experimentalphysik
- Innsbruck 6020 Austria
- christoph.naegerl@uibk.ac.at
-
- Prof. Markus Oberthaler
- University of Heidelberg
- INF 227
- Heidelberg, 69110 Germany
- oberthaler@kip.uni-hd.de
-
- Prof. Maxim Olshanii
- Department of Physics and Astronomy
- University of Southern California
- Los Angeles, CA 90089
- olshanii@physics.usc.edu
-
- Dr. Belén Paredes
- Max-Planck-Institut für Quantenoptik
Hans-Kopfermann-Str. 1
D-85748 Garching, Germany
- Belen.Paredes@mpq.mpg.de
-
- Dr. Dmitry Petrov
- ITAMP
- 60 Garden Street, MS 14
- Cambridge, MA 02138
- dpetrov@cfa.harvard.edu
-
- Prof. David E. Pritchard
Room 26-237
77 Massachusetts Avenue
Massachusetts Institute of Technology
Cambridge, MA 02139-4307
dpritch@mit.edu
-
- Prof. Halina Rubinsztein-Dunlop
- University of Queensland
- Physics Department
- S. Lucia QLD, 4072, Australia
- halina@physics.uq.edu.au
-
- Prof. Jörg Schmiedmayer
- Univ. of Heidelberg
- Philosophenweg 12
- D69120 Heidelberg, Germany
- schmiedmayer@atomchip.org
-
- Prof. Joseph Thywissen
- University of Toronto
- 60 Saint George Street
- Toronto, ON, M5S1A7 Canada
- jht@physics.utoronto.ca
-
- Dr. Sergey Vasiliev
- Department of Physics
- University of Turku
- Turku, 20014 Finland
- servas@utu.fi
-
- Prof. David S. Weiss
- Penn State University
- 104 Davey Lab
- University Park, PA 16802
- dsweiss@phys.psu.edu
-
- Dr. Vladimir Yurovsky
- Tel Aviv University
- Ramat Aviv
- Tel Aviv, 69978 Israel
- volodia@post.tau.ac.il
|
Workshop Schedule
Monday, October 4, 2004
Phillips Auditorium (all
day)
|
| 8:45-9:00 a.m. |
WELCOME |
|
One-Dimensional Gases |
| 9:00-9:40 a.m. |
D. Pritchard: New Approaches
to Confined Atom Interferometers |
| 9:40-10:20 a.m. |
D. Blume: Temperature-Dependent Study
of Bose Gases: Crossover from Three- to One-Dimensional Behavior |
| 10:20-10:50 a.m. |
Coffee |
| 10:50-11:30 a.m. |
M. Olshanii: Interactions and
Interference: Beyond Mean-Field |
| 11:30-12:10 p.m. |
E. Lieb: Rigorous Results on
Bose Gases in Various Dimensions |
| 12:10-12:50 p.m. |
M. Bromley: Manipulation of
Matter Waves Using Periodic Potentials |
| 12:50-2:20 p.m. |
Lunch |
|
Strongly Correlated
Systems |
| 2:20-3:00 p.m. |
D. Haldane: Nematic States
of Quantum Spin Chains and Optically-Trapped Spin-1 Bosons |
| 3:00-3:40 p.m. |
B. Paredes: Tonks-Girardeau Gas in
an Optical Lattice |
| 3:40-4:10 p.m. |
Coffee |
| 4:10-4:50 p.m. |
E. Demler: Boson-fermion mixtures
in optical lattices |
| 4:50-5:30 p.m. |
M. Cazalilla: Atomic Luttinger Liquids
and Fermionized Bose Gases |
| 5:30-6:30 p.m. |
Reception in Perkin Lobby |
|
Tuesday, October 5, 2004
Phillips Auditorium (all
day)
|
Low-dimensional Experiments
|
| 9:00-9:40 a.m. |
M. Oberthaler: Nonlinear
Wave Dynamics in One Dimensional Periodic Potentials |
| 9:40-10:20 a.m. |
Z. Hadzibabic: An Array of
2D Bose-Einstein Condensates in an Optical Lattice |
| 10:20-10:50 a.m. |
Coffee |
| 10:50-11:30 a.m. |
H. Nägerl: A
Two-Dimensional Bose-Einstein Condensate in an Optical Surface
Trap |
| 11:30-12:10 p.m. |
H. Rubinsztein-Dunlop: Bose-Einstein
Condensates on an Atom Chip |
| 12:10-12:50 p.m. |
J. Thywissen: Towards Ultracold Fermions
on a Chip |
| 12:50-2:20 p.m. |
Lunch |
Scattering in Waveguides
|
| 2:20-3:00 p.m. |
M. Moore: Scattering in Tight Atom Waveguides
and Confinement Induced Resonances |
| 3:00-3:40 p.m. |
B. Granger: Strongly Interacting Spin-Polarized
Fermions in Quasi-1D Traps |
| 3:40-4:10 p.m. |
Coffee |
| 4:10-4:50 p.m. |
D. Petrov: Interparticle Interaction in
Quasi-2d Gases and Prospects for Bcs Transition |
| 4:50-5:30 |
V. Yurovsky: Effect of Feshbach Resonances
on Collisions in Atomic Waveguides |
|
Wednesday, October 6, 2004
Phillips Auditorium (all
day)
|
Tonks-Girardeau and
Kosterlitz-Thouless
|
| 9:00-9:40 a.m. |
Weiss: Observation of a 1D Tonks-Girardeau gas |
| 9:40-10:20 a.m. |
Esslinger: Quantum Degenerate Gases in
Optical Lattices |
| 10:20-10:50 a.m. |
Coffee |
| 10:50-11:30 a.m. |
C. Fertig: Transport Studies of a 1D Bose Gas
in a 1D Optical Lattice |
| 11:30-12:10 p.m. |
- S. Vasiliev: Experiments with Dense 2D Atomic Hydrogen Gas
on Liquid Helium Surfaces
|
| 12:10-1:10 p.m. |
Lunch (early and short) |
Atom Guides and Applications
|
| 1:10-1:50 p.m. |
D. Anderson: BEC Waveguide Michelson Interferometer
on a Chip |
| 1:50-2:30 p.m. |
P. Krüger: Towards 1d Experiments on Atom
Chips |
| 2:30-3:10 p.m. |
J. Fortágh: Bose-Einstein Condensates
in Tailored Micro-Potentials |
| 3:10 p.m. |
Adjourn |
Abstracts
BEC Waveguide Michelson Interferometer on a
Chip
Dana Z. Anderson,1 Victor M. Bright,2 Eric
Cornell,1 Quentin Diot,1 Mara Prentiss,3 Stephen R. Segal,1 Ying-Ju
Wang,1 and Saijun Wu3
1Department of Physics and JILA, University of
Colorado and National Institute of Standards and Technology,
University JILA UCB 440, Boulder CO 80309-0440
2Department of Mechanical Engineering, University of Colorado,
Boulder, CO 80309
3Department of Physics, Harvard University, Cambridge, MA, 02138
An atom Michelson interferometer is formed using a 1-dimensional
waveguide configuration. Atoms are trapped and cooled in a pyramid
MOT, then transported to a Ioffe-Pritchard trap where they undergo
further cooling but remain above the critical temperature for
the formation of a Bose-Einstein condensate. The cooled atoms
are then launched towards and captured on an atom chip. The magnetic
waveguide and other atom manipulation structures on the chip
are produced by current-carrying wires lithographically patterned
on the chip substrate. A one-dimensional waveguide is formed
by a current in one of the central wires acting in conjunction
with a bias magnetic field. Mounted on the chip is a pair of
prism-shaped mirrors. Atoms are transported through a small tunnel
lying underneath the first prism to the approximate center of
the atom waveguide region between the mirrors, where they are
again trapped, then evaporatively cooled to form a condensate.
The two mirrors are arranged to form a standing light wave, which
lies parallel to and directly above the waveguide conductor.
The atoms sitting within the waveguide can thus be subject to
the standing light field.
The initial condensate is split into two, oppositely directed
atom clouds of momenta by exposing the cloud to a double-pulse
standing light field. After a propagating a short time, the atoms
are exposed to an optical "Bragg" pulse, which reverses
their momentum. The atoms thus return to their starting point,
where they are finally exposed to a second double-pulse. Thus
the three exposures of light serve to split, reflect, and recombine
the atoms. Upon re-combination the atoms generally form three
clouds: a zero-momentum ( ) cloud, and a pair of oppositely directed
non-zero ( ) clouds.
The atom optical path length between the initial two propagating
atom clouds is varied either by varying a magnetic gradient along
the waveguide direction, or by giving the initial condensate
cloud an initial velocity. We observe interference in the final
atom cloud configuration by comparing the population of the zero-momentum
cloud with the two non-zero momentum cloud as a function of the
relative phase difference. The interference contrast is seen
to be excellent out to approximately 4 ms. For times on the order
of 10 ms, however, the interference contrast falls to about 20%,
indicating either a real or apparent loss of atomic coherence.
We describe further details of the experiment, and make some
speculations regarding the observed loss of coherence.
|
Temperature-Dependent Study of Bose Gases: Crossover
from Three- to One-Dimensional Behavior
D. Blume and Kwangsik Nho
- Department of Physics
- Washington State University
- Pullman, WA 99164-2814
-
|
Manipulation of Matter Waves Using Periodic
Potentials*
M.W.J. Bromley, B.D. Esry
Department of Physics
Kansas State University
Manhattan, KS 66506
Using a combination of Bose-Einstein condensates and moving
optical lattices, experimentalists have recently demonstrated
the manipulation of the dispersion of a matter wave during expansion
[1,2].
We consider whether it is possible to exert similar control
over a wavepacket during propagation through a static periodic
potential of finite length. A 1-D waveguide model neglecting
atom-atom interactions is used to characterize the effective
mass of matter waves propagating through various periodic potential
structures. It is seen that to vary the effective mass requires
periodic potentials that are relatively strong compared to the
transverse waveguide confining potential, while methods of loading/unloading
into/out of the finite length 1-D potentials are explored.
* This research was supported by the Department of the Navy,
Office of Naval Research, and in part by the Research Corporation.
[1] B.Eiermann et.al Phys. Rev. Lett. 91 060402 (2003)
[2] L.Fallani et.al Phys. Rev. Lett. 91 240405 (2003)
|
Atomic Luttinger Liquids and Fermionized Bose Gases
Miguel A. Cazalilla
Donostia Intl Physics Center
Manuel de Lardizabal, 4
San Sebastian, E-20018 Spain
In this talk, we discuss the correlation properties of one-dimensional
Bose gases. Finite-size effects on the momentum distribution
will be illustrated by considering a model of bosons (a Luttinger
liquid) in a box. We shall also touch upon the differences between
the momentum distribution of a weakly interacting and a strongly
interacting 1D Bose gas at finite temperature. Finally, the different
properties of strongly interacting Bose gases in the continuum
and on the lattice will be described.
|
Quantum Degenerate Gases in Optical Lattices
Tilman Esslinger
ETH Zürich
Quantenelektronik
HPF D 4, Hönggerberg
CH-8093 Zürich, Switzerland
Quantum gases trapped in the periodic potential of an optical
lattice have opened a new experimental window on many-particle
quantum physics. The observation of the quantum phase transition
from a superfluid to a Mott insulating phase in a Bose gas has
offered a first glimpse into the physics which is now becoming
experimentally accessible. I will discuss experiments with one-dimensional
Bose gases and report on first results with a Fermi gas loaded
into a three-dimensional optical lattice.
|
Transport Studies of a 1D Bose Gas in a 1D
Optical Lattice
Dr. Chad Fertig
Laser Cooling and Trapping Group
National Institute of Standards and Technology
100 Bureau Drive, Stop 8424
Gaithersburg, MD 20899-8424
I will report on experimental studies of transport in a trapped
1D Bose gas. We realize a 1D Bose gas by partitioning a magnetically-trapped
BEC into an array of independent "tubes'' using a deep 2D
optical lattice. Dipole oscillations along the tubes are excited
in the presence of a 1D axial "corrugating" lattice.
Surprisingly, small amplitude oscillations are strongly damped
for extremely shallow depths of the corrugating lattice. This
behavior is in striking contrast to previous observations of
undamped oscillations in 3D BEC systems. For deeper corrugating
lattices, the motion becomes strongly over-damped, having a time
to return to equilbrium that can be orders of magnitude longer
than characteristic timescale for tunneling in the lattice. We
also probe the momentum distribution of the atoms, and find that,
remarkably, the extreme inhibition of transport is not accompanied
by band-filling.
|
Bose-Einstein Condensates in Tailored Micro-Potentials
József Fortágh
Physikalisches Institut der Universität Tübingen
72076 Tübingen, Germany
Bose-Einstein condensates in tailored micro-potentials are
bringing closer the realization of integrated coherent atom optics
on a chip. Conceivable are matter wave interferometers for ultra-sensitive
force detection or even quantum bits for quantum information
processing.
Current experiments concentrate on the control of Bose-Einstein
condensates using basic atom optical elements. Recent studies
demonstrate several perspectives and limitations of this technology.
|
Strongly Interacting Spin-Polarized Fermions in Quasi-1D
Traps
- Brian E. Granger
-
- Santa Clara University
- 500 El Camino Real
- 312 Daly Science
- Santa Clara, CA 95053
When confined to quasi-one-dimensional (1D) geometries, spin-polarized
fermions can have strong effective 1D interactions. This opens
up the possibility of studying a fermionic version of the Tonks-Girardeau
gas of impenetrable bosons. In this novel 1D many body system,
recently introduced by a number of groups, strongly interacting
1D fermions are dual to noninteracting 1D bosons. In this talk
I will describe both the two particle scattering physics leading
to these strong effective 1D interactions and the single particle
correlations that these interactions create in the many body
system.
|
An Array of 2D Bose-Einstein Condensates in an Optical
Lattice
Zoran Hadzibabic
Laboratoire Kastler Brossel
Ecole Normale Superieure
Paris, 75005 France
I will discuss our studies of an array of two-dimensional
87Rb Bose-Einstein condensates, created in a one-dimensional
optical lattice. Our lattice potential has a long period, of
several microns, which allows for a large number of atoms (~104)
to be loaded into each site, and for the condensates to be completely
isolated from each other.
We have studied matter wave interference in this system, and
have observed high-contrast interference between 30 condensates
with uncorrelated phases [1]. Our observations are quantitatively
explained with a simple theoretical model which generalizes the
analysis of the interference of two independent condensates.
I will also discuss the possibilities for creating a single
two-dimensional condensate in this setup.
[1] Z. Hadzibabic, S. Stock, B. Battelier, V. Bretin, and
J. Dalibard, quant-ph/0405113.
|
Nematic States of Quantum Spin Chains and Optically-Trapped
Spin-1 Bosons
F. D. M. Haldane
Department of Physics
Princeton University
Princeton NJ 08544-0708
The Mott insulator states of optically-trapped spin-1 bosonic
atoms on a one-dimensional lattice with an odd number of atoms
per well provides a new physical realization of the spin-1 quantum
spin chain. In the absence of exchange splitting between the
spin-0 and spin-2 two-particle scattering cross-sections, the
system has SU(3) symmetry, corresponding to exactly equal-strength
"Heisenberg" and "biquadratic" exchange in
the AKLT parameterization of the spin-1 chain. Exchange splitting
allows a physical realization of the model in a previously-inaccessible
parameter region. There has been controversy about the competition
between nematic order and spontaneous dimerization in the spin-1
chain. I will show how this is resolved using a nematic non-linear
sigma model field-theory description: local nematic correlations
immediately lead to dimerization of odd-integer spin chains.
If time permits, other aspects of one-dimensional physics that
could be realized in optical traps will be reviewed.
|
Towards 1d Experiments on Atom Chips
Peter Krüger
Physikalisches Institut
University of Heidelberg
Philosophenweg 12
69120 Heidelberg, Germany
Cold neutral atoms can be controlled and manipulated in microscopic
potentials near surfaces of atom chips. These integrated micro-devices
combine the known techniques of atom optics with the capabilities
of well established micro- and nanofabrication technology.
We use current and charge carrying structures to form complex
potentials with high spatial resolution only microns from the
surface. In particular, atoms can be confined to an essentially
one-dimensional motion, i.e. the temperature of a cloud can be
smaller than the transverse energy level spacing of the potential.
In the case of a Bose-Einstein condensate (BEC), the transverse
ground state energy can exceed the chemical potential of the
BEC.
In this talk, we will give an overview of our experiments
studying the manipulation of both thermal atoms and BECs on atom
chips. First experiments in the quasi one-dimensional regime
will be presented. These experiments profit from strongly reduced
residual disorder potentials caused by imperfections of the chip
fabrication with respect to previously published experiments.
This is due to our purely lithographic fabrication technique
that proves to be advantageous over electroplating. We have used
one dimensionally confined BECs as an ultra-sensitive probe to
characterize these potentials. These smooth potentials allow
us to explore various aspects of the physics of degenerate quantum
gases in low dimensions.
|
Rigorous Results on Bose Gases in Various Dimensions
Elliott H. Lieb
Princeton University
Jadwin Hall
P.O. Box 708
Princeton, NJ 08544-0708
I will give a brief survey of work that has been going on
for the past 6 years, mostly on ground states of Bose gases,
with various collaborators (Aizenman, Seiringer, Solovej, Yngvason).
These include:
1.) The asymptotic ground state energy of dilute homogeneous
gases in 3 and in 2 dimensions.
2.) Proof that the Gross-Pitaevskii equation is correct in this
limit for trapped gases.
3.) The existence of 100% Bose-Einstein condensation and 100%
superfluidity in this limit.
4.) The verification of Foldy's formula for high density jellium
and of Dyson's conjecture for the 2-component charged Bose gas
in 3D.
5.) Proof of the transition from 3D to 1D behavior (Lieb-Liniger
model) for 3D bosons in long traps.
6.) A model for an optical lattice that displays true quenching
of BEC for interacting bosons when the lattice is "deep"
enough. (Phys. Rev. A 70, 023612 (2004)).
|
Scattering in Tight Atom Waveguides and Confinement
Induced Resonances
Michael G. Moore
Ohio University
Department of Physics Astronomy
Athens, OH 45701
Recent work will be presented on the use of zero-range models
to study low-energy scattering under tight transverse confinement.
The effects of confinement on atom-atom scattering can be investigated
via a Green's function, developed by A. Lupu-Sax, where the Green's
function of the confinement potential, and the low-energy behavior
of the free-space T-matrix of the scatterer are the only inputs.
The approach allows the calculation of multi-channel 1-d scattering
amplitudes, from which the complete Kinetic coefficients can
be determined. In addition, the appearance of Confinement induced
resonances, and their interpretation as a type of Feshbach resonance
will be presented, as well as the influence of the confinement
on near-threshold bound states.
|
A Two-Dimensional Bose-Einstein Condensate in an
Optical Surface Trap
B. Engeser, D. Rychtarik, Hanns-Christoph Nägerl,
and Rudolf Grimm
Institut für Experimentalphysik, Technikerstraße
25, Universität Innsbruck, 6020 Innsbruck, Austria
Phone: +43-512-507 6316, , FAX: +43-512-507 2921,
email: Christoph.Naegerl@uibk.ac.at
We create a single two-dimensional Bose-Einstein Condensate
of Cesium atoms by evaporative cooling in a highly anisotropic
surface trap [1]. Our gravito-optical surface trap is based on
a horizontal evanescent-wave atom mirror in combination with
a horizontally confining optical dipole potential. The pancake-shaped
condensate of a few thousand atoms with an aspect ratio of 50:1
is produced 4 micrometers above the dielectric surface. We detect
the formation of the condensate either by a release-and-recapture
technique along the horizontal direction or alternatively by
inducing a collapse of the condensate at negative scattering
lengths.
The condensate will now allow us to study the effects of reduced
dimensionality on the spectrum of collective excitations and
on the behavior and stability of vortices. For vanishing scattering
lengths it could be possible to detect the anisotropy of the
dipole-dipole interaction. Further, an optical surface lattice
could be created through the interference of two or more evanescent
waves to produce individual one-dimensional traps to study the
Tonks-Girardeau limit of an interacting Bose system.
References
1. D. Rychtarik, B. Engeser, H.-C. Nägerl, and R. Grimm,
Phys. Rev. Lett. 92, 173003 (2004)
|
Nonlinear Wave Dynamics
in One Dimensional Periodic Potentials
Thomas Anker, Michael Albiez, Bernd Eiermann, Rudolf
Gati, Stephan Hunsmann, Markus Oberthaler
Kirchhoff-Institut für Physik
Universität Heidelberg
Im Neuenheimer Feld 227
69120 Heidelberg
Nonlinear matter wave dynamics in onedimensional periodic
potentials is very diverse. In this talk we will present our
experimental results on two different wave phenomena leading
to the formation of non-spreading wave packets.
The first part of the talk is devoted to the first realization
of atomic gap solitons of 87Rb [1]. In this experiment we utilize
a weak periodic potential to realize anomalous matter wave dispersion,
which can be described with an effective negative mass. This
allows the realization of bright solitons although the atom-atom
interaction is repulsive. Since our experiment is carried out
in the quasi-one-dimensional regime, the observations are in
very good agreement with the predictions of a simple one-dimensional
model.
We will also present our first results on the propagation
of nonlinear matter waves in the regime with moderate atomic
densities and deep periodic potentials. Here the dynamics is
conveniently described by looking at the atomic tunnelling current
from well to well. One prominent effect due the atom-atom interaction
is the possibility that a sufficiently high density difference
between two wells can prevent further tunnelling and thus halts
the wave packet dynamics - an effect called "macroscopic
quantum self trapping"[2].
[1] B. Eiermann et al., Phys. Rev. Lett. 92, 230401
(2004).
[2] A. Trombettoni and A. Smerzi, Phys. Rev. Lett. 86,
2353 (2001).
|
Interactions and Interference: Beyond Mean-Field
Maxim Olshanii
Department of Physics and Astronomy
University of Southern California
Los Angeles, CA 90089
In collaboration with Marvin Girardeau, Vanja Dunjko,
Hieu Nguyen,
Marc Jeffrey, and Kunal Daas.
Parameters of the recent experiments with single-mode one-dimensional
atom traps (NIST, ETHZ, PennState) belong to the domain of strong
correlations with the quantum degeneracy parameter ranging from
.5 to 5. Thus a non-perturbative, beyond-mean-field approach
is needed to address the questions of interaction-induced limitations
on performance of the future wave-guide-based interferometers.
In this presentation I will describe two gedanken experiments,
the first being related to the Ramsey-Borde interferometric scheme,
while the second to the Young's one. Both models constitute non-integrable
extensions of the integrable Lieb-Liniger model, and thus allow
for a non-perturbative treatment. The first process is a half-cycle
of the adiabatic population inversion between two guides, with
an immediate interferometric reading in the end. The second scheme
deals with the emergence of interference fringes after a phase
imprinting pulse.
The probably dominant effect of interactions -- degradation
of coherence between splitting and recombination -- still remains
an intractable problem. I will further discuss several two-body
models describing interaction of mutually interacting atoms with
interferometric elements: solutions generated by these models
indicate the potential difficulties in treating the many-body
case.
In all cases described above the primary object of interest
is the relationship between the fringe visibility and degree
of quantum degeneracy.
|
Tonks-Girardeau Gas in an Optical Lattice
Belén Paredes
Max-Planck-Institut für Quantenoptik
Hans-Kopfermann-Str. 1
D-85748 Garching, Germany
I will report on our recent work on the preparation of a Tonks-Girardeau
gas in an optical lattice. I will discuss the experimental realization
as well as the theoretical approach based on fermionization that
we have developed to describe the finite-inhomogeneous-finite-temperature
Tonks-Girardeau gas observed in the experiment.
I will finally briefly discuss our recent ideas regarding
the efficient simulation of random systems.
|
Interparticle Interaction in Quasi-2d Gases
and Prospects for Bcs Transition
D.S. Petrov, M.A. Baranov, and G.V. Shlyapnikov
ITAMP
60 Garden Street, MS 14
Cambridge, MA 02138
Recent progress in trapping and cooling of neutral atoms allows
one to tightly confine the particle motion in one direction to
zero point oscillations and thus create the gas which is kinematically
two-dimensional. The interparticle interaction has then a quasi-2D
character and depends logarithmically on the relative energy
of colliding particles. We analyse the s-wave scattering in this
quasi-2D regime and find that the scattering amplitude and, hence,
the interaction strength are sensitive to the frequency of the
tight confinement.
The creation of quasi-2D Fermi gases will open new handles
on achieving the superfluid BCS transition. In degenerate quasi-2D
Fermi gases, most important are collisions at energies close
to the Fermi energy which is now proportional to the (2D) density
of the gas. Then, due to the logarithmic dependence of the interparticle
interaction on the particle energies, the exponential dependence
of the critical temperature on the interaction strength transforms
to a power law dependence of this temperature on the density.
This a striking difference from the 3D case. In a two-component
Fermi gas, the s-wave pairing is possible between atoms in different
internal states. We propose to reach the BCS transition by adiabatic
decrease of the 2D density or by variations of the potential
of the tight confinement.
|
New Approaches to Confined Atom Interferometers
Dave Pritchard
Center for Ultracold Atoms at MIT and Harvard
Interferometers in which the atoms are held localized in a
trap or waveguide (rather than allowed to propagate in free space)
offer numerous scientific opportunities and technical advantages.
However, progress on the most popular track - atom chips with
microfabricated wires that generate magnetic waveguides - has
been hampered by several significant obstacles. I will describe
several alternative approaches that we are pursuing, with preliminary
results.
|
Bose-Einstein Condensates on an Atom Chip
Halina Rubinsztein-Dunlop
Centre for Biophotonics and Laser Science, School
of Physical Sciences, University of Queensland, St. Lucia, QLD.
4072, Australia
Phone: +61-7-3365 3139, email: halina@physics.uq.edu.au
Ultra-cold neutral atoms and Bose-Einstein condensates (BECs)
are providing some fascinating insights into the fundamental
nature of matter. A recent development, the "Atom Chip",
provides a reliable and versatile way to produce and manipulate
condensates and also offers the possibility of realising new,
chip-based quantum devices. The quest for realising coherent
waveguides, beamsplitters and interferometers for matter is driving
progress in this field at an astounding rate.
We have recently produced BECs on a new type of atom chip
based on silver foil. We fabricate atom chip with thick wires
capable of carrying currents of several amperes without overheating.
The silver surface is highly reflective to light resonant with
optical transitions used for Rb. The pattern on the chip consists
of two parallel Z-trap wires, capable of producing two-wire guide,
and two additional endcap wires for varying the axial confinement.
We describe our experimental procedure for producing condensates
in magnetic microtraps formed within 1 mm of surface of the chip.
Recent experiments have observed that cold atom clouds fragment
into lumps when brought close to the chip surface. This results
from a perturbed trapping potential caused by nanometer deviations
of the current path through the wires on the chip. We have also
seen fragmentation of cold clouds at distances below 100 mm from
the wires and are investigating the origin of the deviating current.
We also investigate the dynamics of atoms in these microtraps.
|
Towards Ultracold Fermions on a Chip
S. Aubin, M. Extavour, S. Myrskog, A. Stummer, and
J. H. Thywissen
Department of Physics
University of Toronto, Canada
In a new lab in Toronto, we have been working towards loading
quantum degenerate Potassium 40 onto an atom chip. Since microfabricated
magnetic traps can have high aspect ratios, such a system will
enable the study of quasi-one-dimensional Fermi gases, as well
as load optical traps for either one- or two-dimensional confinement.
We will present our motivation for choosing this technical approach,
the latest experimental progress, and some ideas for future experiments.
|
Experiments with Dense 2D Atomic Hydrogen Gas on
Liquid Helium Surfaces
S. Vasilyev, J. JÄarvinen, and S. Jaakkola
University of Turku
- Turku, Finland
-
|
Observation of a 1D Tonks-Girardeau Gas
David S. Weiss
Penn State University
104 Davey Lab
University Park, PA 16802
I will describe our experiments on 1D Bose gases. We use a
combination of conservative light traps to prepare and study
atoms in 1D at nearly zero temperature. We can scan across coupling
regimes and we have access to several observables with which
to test the exact 1D Bose gas theory [1,2] . In particular, I
will discuss our observation of a Tonks-Girardeau gas[3].
[1] E.H. Lieb and W. Liniger, Phys. Rev. 130, 1605 (1963).
[2] M. Olshanii and V. Dunjko, Phys. Rev. Lett. 91, 090401 (2003).
[3] T. Kinoshita, T. Wenger, and D. S. Weiss, Science 305, 1125
(2004).
|
Effect of Feshbach Resonances on Collisions
in Atomic Waveguides
Vladimir Yurovsky
- Tel Aviv University
- Ramat Aviv
- Tel Aviv, 69978 Israel
A problem of collisions of atoms with two-channel zero-range
interaction under cylindrical harmonic confinement is solved
by using of a renormalization procedure. A matching of the solution
to a solution of the related one-dimensional problem leads to
relation between the one-dimensional and three-dimensional scattering
parameters.
At low collision energies the confined scattering amplitude
can be approximated by the one-dimensional one. At higher energies
the opening of transverse channels leads to resonances in the
confined scattering amplitude. Its average behavior can be approximated
by the amplitude of three-dimensional free collisions.
The confined two-body system has two or one bound states below
or above the resonance, respectively. Shallow bound states are
similar to ones of the related one-dimensional system, while
deep ones are similar to bound states of two free atoms. A Feshbach
resonance also affects a one-dimensional three-body scattering.
|
ACCOMMODATIONS
Listed below are the names and, where possible, the 800 numbers
of hotels and a bed and breakfast agent to assist you in getting
accommodations for the upcoming Workshop.
It is especially important that you book a room for the
workshop right away as the fall is a very busy time in Cambridge,
and you might not be able to get one of the cheaper bed and breakfasts.
As housing is expensive in Cambridge/Boston, you may wish to get
together with a friend and share a room.
The hotels are within walking distance of the Institute, the
Sheraton a short walk and the other two longish walks. They all
are on bus routes:
Best Western Homestead Inn, 220 Alewife Brook Parkway, Cambridge,
MA 02138; (617) 491-1890 or 1 (800) 528-1234
Harvard Manor House, 110 Mt. Auburn St., Cambridge, MA 02138
(617) 864-5200
Sheraton-Commander, 16 Garden St., Cambridge, MA 02138; (617)
547-4800 or 1 (800) 325-3434
Boston Reservations/Boston Bed & Breakfast, Inc., 1643
Beacon St., Suite
23, Waban, MA 02168; (617) 332-4199; Fax: (617) 332-5751; e-mail:
bostonreservations@bostonreservations.com
All of this information plus more is on the ITAMP web page
at http://www.cfa.harvard.edu/itamp under "living
accommodations."
We recommend your booking through Boston Reservations/Boston
Bed & Breakfast, as in most cases they can get you a room
at lower cost than a cold call will get you. If you tell them
you are attending a workshop at the Harvard Observatory, they
will make every effort to book you at a bed and breakfast, or
hotel if you wish, in close proximity. They have many comfortable
accommodations in the surrounding neighborhood, and previous workshop
participants have been very satisfied with their rooms.
We also strongly advise your not bringing or renting a car.
There is no visitor parking at the Observatory and most on-street
parking in Cambridge is designated for Cambridge residents only.
There are few places in Cambridge and Boston that aren't easily
accessible by public transportation and we recommend it highly.