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Josephson phase qubit circuit for the evaluation of advanced tunnel barrier materials

2008; IOP Publishing; Volume: 22; Issue: 1 Linguagem: Inglês

10.1088/0953-2048/22/1/015004

1361-6668

Jeffrey S. Kline, Haohua Wang, Seongshik Oh, John M. Martinis, David P. Pappas,

Semiconductor Quantum Structures and Devices

We have found that crystalline Josephson junctions have problems with the control of critical current density that decrease the circuit yield. We present a superconducting quantum bit circuit designed to accommodate a factor of five variation in critical current density from one fabrication run to the next. The new design enables the evaluation of advanced tunnel barrier materials for superconducting quantum bits. Using this circuit design, we compare the performance of Josephson phase qubits fabricated with MgO and Al2O3 advanced crystalline tunnel barriers to AlOx amorphous tunnel barrier qubits.