Magnetic Injection Scheme for The Atom Laser

Karl LundquistREU Summer 2010

Raithel LabAugust 17 2010

Outline

• Overview of current generation atom laser setup

• Theory/Simulation of magnetic injection• Experimental setup of magnetic injection

o In the vacuum oElectronicsoEnclosureoSoftware

Overview of current setup

• Zeeman slower• Primary MOT• Pusher Beam• Secondary MOT• Magnetic Injection• Magnetic Compression• Surface Adsorption

evaporative cooling• Continuous BEC!

Basic idea behind magnetic injection

• Transferring atom into evaporative cooling region with light would cause atoms to gain heat.

• Instead, if we transfer atoms with magnetic field only, the process can be slow enough to be adiabatic.

• From secondary MOT, we can transfer atoms along the guide using a moving magnetic field minimum.

Magnetic field sources in the injection region

• Guiding wires produce transverse trapping potential (~250 amps)

• Injection coils produce moving magnetic field minimum (2-3 amps each)

• Racetrack coils produce quadrupole magnetic field for secondary MOT

Coil cur rent profiles

Period ~ 1second

Injection Simulation

High Current Power Supply

• HP6651A• 0-8 Volts• 0-50 Amps• Low gauge wire and

aluminum rods for high current transport

Circuit setup• Need easy way to control

current in each coil with low voltage signal from computer

• Traditional differential amplifier setup

• Must drop signal over R test in order to maintain equilibrium

• op-amp pushes transistor base until allowed current causes required voltage drop

• R=.5 Ohms• I=V/R => I = 2V*(1/Ohm)• Directly proportional

Testing

• Measuring voltage across load resistor will indicate the amount of current flowing through coils

• A circuit can be tested by checking that the signal in is identical to the signal out

Cooling

• 2-3 Amps through transistors makes them very hot

• use heat sinks and high powered fans too keep them cool

Circuit Control• United Electronics

Industries PowerDNA Cube

• Allows for DAQ communication via Ethernet port

• LabVIEW userinterface

Acknowledgments

• Georg Raithel• Andrew Schwarzkopf• Andrew Cadotte• David Anderson• Eric Paradis• Mallory Traxler

• Sarah Anderson• Erik Power• Betty Slama• Stefan Zigo• Kareem Hegazy• Kevin Smith

Much thanks to everyone in Raithel Lab for a great summer!