Big Bertha

Designed by Webb and built by SHE, this machine has a base temperature of 3 mK (on some good days) but can usually get down to 7 mK using only a mechanical pump for circulation. It is equipped with an 8 Tesla superconducting magnet. In its last cooldown, Big Bertha was used to measure weak localization effects with a sensitivity in resistance change of less than 1 part in ten thousand.

Mini-fridge

Set up for high frequency measurements up to 1GHz, this small dilution refrigerator has a base temperature of 20 mK. Racks with electronic equipment for high frequency measurements are shown in the back while the small seven Tesla magnet is shown in the lower part of the picture.

Top-loader

Designed and built by Webb and A. Benoit, it allows fast sample exchange (6 hours from 80mK to room temperature and back to 80mK) with a base temperature of 40 mK. It is equipped with a 16 Tesla superconducting magnet from Oxford Research. Besides a standard insert for typical measurements, a home built insert with cryogenic amplifiers close to the sample was designed to measure shot noise spectra of point contacts, tunnel barriers, and quantum dots with a 1MHz bandwidth.

Designed by Oxford Research for "high" temperature measurements (between 1.4 K and 293 K), this cryostat is equipped with both axial and transverse low field (5000 Gauss and 2000 Gauss) superconducting magnets. Multiple inserts are available, including one that holds two cryogenic amplifiers close to the sample, and has an LED-photodetector pair for precise in-situ calibration. This insert is currently being used to measure the spin shot noise produced by electrons tunneling between ferromagnetic metals.

A class 1000 clean room for sample fabrication which includes a JEOL JSM-840A scanning electron microscope (SEM) capable of defining mask features down to 30 nm for nano-lithography, wire and ribbon bonding machines to make electrical connection to the mesoscopic devices, high purity gold thermal evaporation system, optical microscopes, and a general purpose deposition system for sputtering, thermal and e-gun evaporation, and ion milling.

• Lock-in amplifiers (analog PAR-124's, digital Stanford Research up to 20 MHz, and digital PAR's).

• Spectrum analyzers (Agilent 10MHz, HP 26.5 GHz, Stanford Research)

• Low noise preamplifiers (Perkin Elmer, Ithaco, and specific band high frequency amplifiers).

• 26.5GHz HP network analyzer with two 26.5GHz function generators  (shown to the right).

• All the other experimental "goodies": DVM's, low noise sources, power supplies, filters, etc., shown below.