Transcript Slide 1

Smita Speer, Howard University
Mentor: Ryan Price, University of Maryland
Bose-Einstein Condensates in Lab
 Rubidium atoms travel through Zeeman slower where atoms are slowed by the
nearly resonant pump laser (780nm).
 Rb atoms enter the magnetooptical trap (MOT) where lasers in
orthogonal direction are used to cool the atoms
further and a magnetic field is applied as a
restoring force to keep atoms in
place.
 Magnetic Trap is used to hold
atoms while evaporative
cooling reduces temperature of
atoms to a few billionths of a
degree above absolute
zero [1,3].
[1] Cannon, Ben, Stone, Daniel, Price, Ryan. Light
Analysis of Ultra-cold Magneto Optical Trap.
[3] Steven Chu, The Manipulation of Neutral
Particles. 1997.
Fig. 1. BCIT. 2003. BCIT MOT.
Effect on BECs
 Fluctuations in the current result in changes in the
magnetic fields used to hold ultracold atoms.
 Magnetic traps are affected more noticeably by these
fluctuations.
 If the magnetic fields vary, the atoms can become too hot,
scatter and ruin results [2].
[2] Lee, S. –K., Romalis, M. V., J. Appl. Phys. 103,
084904 (2008).
Current Fluctuation
 The figure on the left is a breadboard in our
lab used to measure how noisy our power
source is and how it can be filtered by using
bypass capacitors to stabilize voltage and
power flow.
 Storing energy
 Blocking DC
Fig. 2. Set up on
breadboard in electronics
lab
Fig. 3. Electronics Bus. 2012. Bypass Capacitor
Operation and Noise Ripple Characteristics
Operational Amplifier
Configuration
 We designed an op amp set up to provide more stable current
used in our experiment.
Liquid Cooling Plates
Set Up within
Mounting Rack
PA05
HS18
Controlling Op Amp
 To control the op amp, we designed a printed circuit
board (pcb) to attach to the op amp’s pins. The pcb also
offers us different ways to measure the current and
compare with past methods for accuracy.
 Components on the board further stabilize the current
outputting from the op amp.
 Resistors (current limit and
compensation)
 Capacitors (Bypass and compensation
 Diodes and varistor (surge protection)
Fig. 4. One of our resistors on a
nickel
PCB Schematic & Board Designs
Finished Board
Set up within lab
Current across op amp – current
outputted
Current outputted
Op amp set up
Conclusions
 Op amp design provides cleaner current. Can replace
several supply coils in lab with external power source.
 Future tests of system
 Examine different methods of current measurement on pcb
and on coils
 Design separate box for increased precision of control of the
current