We are currently looking for undergraduate researchers to work on the following
FPGA-based high-speed laser offset lock [Experiment]
This project will offset lock a laser to a
master laser. The offset lock will use an FPGA, direct digital synthesis
(DDS), and a microprocessor to lock the laser so that it can be scanned and
jumped at high speeds over a range of ± 7 GHz. This locking technique will
allow us to probe many different atomic transitions over a short time and
at high magnetic fields. If the lock is sufficiently good, then the offset
laser can be used for Raman transitions and 4-wave mixing in gases of
4-wave mixing for imaging of ultracold atoms [Experiment
- joint with Novikova group]
This project will use the nonlinear process of 4-wave mixing to
image cold atoms in a magneto-optical trap: 2 probe lasers separated by a
hyperfine splitting are directed at a cold atomic cloud at a small angle
from each other, so that the process of 4-wave mixing generates a
third beam at a commensurate angle. This third beam can then be used for
background free imaging of cold atoms.
Atom chip construction [Experiment]
The objective of this project is to construct a multilayer atom
chip by bonding ultrathin wires to a substrate. This "homemade" atom chip can
then be used for micro-magnetic trapping and RF evaporation
of ultracold atoms. The addition of multiple layers to the atom chip
permits the integration of RF and microwave transmission lines for futher
manipulation of the internal and external atomic states.
Ultra-stable, agile microwave source [Experiment]
Laser cooling can cool atoms to 10-100 microK, but to achieve
lower temperatures, in the 10-100 nK range, evaporative cooling is the only
reliable technique. For atoms in a magnetic trap, a radio-frequency (RF) or a
microwave magnetic field can selectively remove hot atoms and thus
evaporatively cool the atomic sample. The RF and microwaves can also be used
to manipulate the internal and external states of the ultracold atoms.
This RF source must be capable of performing stable, repeatable,
and rapid RF frequency sweeps for periods of a few milliseconds. Such an RF
source can be constructed from a Direct Digital Synthesis (DDS) RF source in
combination with a microprocessor controlled ethernet connection and
an FPGA to load specfic sweep information from a computer and a TTL trigger to
control the exact timing of the RF sweep. We need to construct a high
power source that can produce RF frequency sweeps in the ranges
of 1-30 MHz, 250-280 MHz, 450-500 MHz, and 1250-1400 MHz.
High resolution imaging of ultra-cold atoms [Experiment]
High resolution imaging of ultra-cold atoms Most measurements of
ultra-cold atom properties such as temperature and density are determined from
CCD absorption images of the atomic clouds. Since these measurements rely on
the distances between points on the images, the imaging resolution and any
optical distortions determine the accuracy and precision of such measurements.
A high resolution, low distortion imaging system is necessary for
high quality images and measurement. We need to design, construct, and
test a high resolution imaging system for precision optical measurements of
High fidelity laser intensity controller and stabilizer
A high power far off-resonance laser can be used to trap
ultra-cold atoms: If the laser is detuned below resonance (red-detuned), then
the atoms are attracted to high-intensity part of the laser beam; if the laser
is detuned above resonance (blue-detuned), then the atoms are repelled from the
high-intensity part of the laser beam. The strength of the trap, i.e. how
tightly the atoms are confined, is directly proportional to the intensity.
We are interested in precision control and stabilization of the intensity, so
that we can reliably control the trap strength. Intensity noise tends to heat
the atoms, and so we must suppress it as much as possible. The intensity can be
controlled by passing the laser through an acousto-optical modulator (AOM). By
monitoring the laser power with a photodiode, one can use PID feedback to
stabilize (and control) the laser power.
Nuclear anapole moment of potassium [Theory]
We want to know the expected size of the parity-violating nuclear
anapole moment of naturally occuring potassium isotopes (39K, 40K,
and 41K). Additionally, we are also interested in the size of the
anapole induced mixing of the 4S1/2 hyperfine ground states with
excited 4P1/2 states, in order to determine the expected size of
parity-violating spectroscopic signals.
Cold collisions between atoms and molecules [Theory]
We want to determine the rethermalization rate and diffusion
distance for cold molecules at 4 K with 87Rb atoms in a MOT at 200
mK. The calculation is necessary for determining whether molecules
from a molecular beam can be effectively cooled by a MOT "refrigerator" and
then subsequently trapped.