written by Asma Khalid, Rabiya Salman, and Muhammad Sabieh Anwar
published by the LUMS School of Science and Engineering

Superconducting Quantum Interference Devices (SQUIDs) are sensitive probes that can detect small changes in the magnetic field. They take advantage of two important properties of superconductors, namely flux quantization and the Josephson effect. Furthermore, SQUIDs demonstrate quantum effects on the macroscopic scale, such as macroscopic wavefunctions, quantum interference and quantum mechanical tunneling. SQUID is a commercially available high temperature superconducting (HTS) DC SQUID magnetometer that will be used for our prototypical experiments.

The objectives of this experiment are:

1. study the basic principles underlying SQUID applications,
2. observe zero resistance of superconductors and examine the superconducting phase transition,
3. observe the DC Josephson effect,
4. observe the periodically varying critical current in the resistive mode of the SQUID,
5. learn about the detection of extremely small magnetic fields by converting them into voltages and using a feedback loop,
6. measure the electrical characteristics of SQUID Josephson junctions and
7. build an ac/dc nano-voltmeter.

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Last Modified February 12, 2012

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