Slide #1.

High Current Stabilization Circuit for Ultracold Atom Trap Smita Speer, Howard University Mentor: Ryan Price, University of Maryland
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Slide #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 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.
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Slide #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, 084904 (2008).
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Slide #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. 2012. Bypass Capacitor Operation and Noise Ripple Characteristics
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Slide #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
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Slide #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
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Slide #7.

PCB Schematic & Board Designs
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Slide #8.

Finished Board
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Slide #9.

Set up within lab Current across op amp – current outputted Current outputted Op amp set up
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Slide #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
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