September 15, 2008
The Josephson tunnel junction is a unique electronic circuit element which is both non-linear and non-dissipative. This combination make it well suited to measure the state of a quantum mechanical system with high fidelity and minimum back-action. I will describe the operation of a new type of Josephson amplifier, based on a dynamical bifurcation, and demonstrate how it can be used to measure a quantum spin ½ system.
Irfan Siddiqi received his AB (1997) in chemistry & physics from Harvard University. He then went on to receive a PhD (2002) in applied physics from Yale University, where he stayed as a postdoctoral researcher until 2005. Irfan joined the physics department at the University of California, Berkeley in the summer of 2006. His research group, the Quantum Nanoelectronics Laboratory, investigates the quantum coherence of various condensed matter systems ranging from microscopic nanomagnets such as single molecule magnets to complex macroscopic electrical circuits. In 2006, Irfan was awarded the George E. Valley, Jr. prize by the American Physical Society for the development of the Josephson bifurcation amplifier. He has also been awarded the Office of Naval Research Young Investigator Award, the Air Force Office of Scientific Research Young Investigator Award, the Hellman Family Faculty Fund, and the UC Berkeley Chancellor's Partnership Faculty Fund.