Materials Characterization for Quantum Computation

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This project involves testing state of the art superconducting devices used for quantum computing and quantum**information processing. The building block of the superconducting quantum computer is the Josephson**junction. This is typically a sub-micron scaled tunnel junction lithographically patterned from a trilayer of**Nb/AlOx/Nb. For quantum computing as well as high performance SQUID sensors, this superconducting**device must have a very stable quantum tunneling resistance. Materials aspects have been found to be**responsible for the ultimate noise limit for such devices. For example, defects within or in the vicinity of the**oxide barrier can fluctuate causing a low frequency noise (1/f noise) in the tunneling resistance. Similarly**magnetic particles on the surface of the device can fluctuate, causing 1/f noise in the background magnetic flux**seen by the device. For the application of quantum computing, this noise causes decoherence, which is a loss of**the quantum information. This limits the effectiveness of the qubit. In the case of SQUID magnetometers, this**produces a residual magnetic noise that limits the sensitivity of the sensor.**The proposed project will work with D-wave, a company working on superconducting quantum computation,**to set up a reliable, efficient way to characterize the quality of the Josephson junction based devices in order to**make higher performance quantum computers.**