1. High Current Stabilization Circuit for Ultracold Atom Trap
Smita Speer, Howard University
Mentor: Ryan Price, University of Maryland

2. 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 magneto-
optical 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].
Fig. 1. BCIT BCIT MOT.
[1] Cannon, Ben, Stone, Daniel, Price, Ryan. Light Analysis of Ultra-cold Magneto Optical Trap.
[3] Steven Chu, The Manipulation of Neutral Particles .

3. 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, (2008).

4. 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 Bypass Capacitor Operation and Noise Ripple Characteristics

5. 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

6. 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

7. PCB Schematic & Board Designs

8. Finished Board

9. Set up within lab Current across op amp – current outputted
Op amp set up

10. 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