High Current Stabilization Circuit for Ultracold Atom Trap

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 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].[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

Fig. 2. Set up on breadboard in electronics lab

Fig. 3. Electronics Bus. 2012. Bypass Capacitor Operation and Noise Ripple Characteristics

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

Operational Amplifier ConfigurationWe designed an op amp set up to provide more stable current used

in our experiment.

PA05

Liquid Cooling Plates

HS18

Set Up within Mounting Rack

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 compensationDiodes and varistor (surge protection)

Fig. 4. One of our resistors on a nickel

PCB Schematic & Board Designs

Finished Board

Set up within lab

Op amp set up

Current outputted

Current across op amp – current outputted

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 coilsDesign separate box for increased precision of control of the

current