Tuesday, 10/5/2004 Session Title: Quantum Computing - I Session Chairs: David Tilbrook, CSIRO & Vijay Patel, Stony Brook University Paper Number: 2EL05 Start Time: 1:30pm Session Type: Poster Fast measurement of a flux qubit based on a Nb/AlOx/Nb rf-SQUID. V.V. Kuznetsov, D.A. Bennett, L. Longobardi, V. Patel, J. Mannik, W. Chen, J.E. Lukens, Stony Brook University, Stony Brook, NY 11794-3800 A high speed readout for flux qubits has been developed using a hysteretic dc SQUID magnetometer. Special care in the design and filtering of the magnetometer has been taken to prevent it from degrading the coherence of the qubit prior to the measurement of the qubit’s state. Readout is initiated using a pulsed bias flux on the magnetometer, which then switches to its finite voltage state or not depending on the state of the qubit. This pulse length can be as short as several nanoseconds, which sets the time resolution of the measurement. The flux pulses, which are inductively coupled to the magnetometer, pass through a 1 cm long lossy microstrip filter, which has low distortion for the pulse but cuts off exponentially for frequencies above about 1 GHz. Preliminary measurements indicate that it will be possible to achieve a high fidelity readout using this device. This work is supported in part by AFOSR and ARDA through a DURINT program and by NSF.
Tuesday, 10/5/2004
