Dresden 2009 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 44: Transport: Quantum Coherence and Quantum Information

TT 44.8: Talk

Thursday, March 26, 2009, 16:00–16:15, HSZ 304

Bi₂Sr₂CaCu₂O_8+δ intrinsic SQUIDs as candidates of high-T_c phase qubits — •X. Y. Jin¹, J. Lisenfeld^1,2, Y. Koval¹, A. Lukashenko^1,2, C. Bergmann¹, A. V. Ustinov^1,2, and P. Müller¹ — ¹Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erwin-Rommel-Strasse. 1, D-91058 Erlangen, Germany — ²Physikalisches Institut, Universität Karlsruhe (TH), Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe, Germany

An intrinsic SQUID is a superconducting ring made of Bi₂Sr₂CaCu₂O_8+δ single crystal, intercepted by two intrinsic Josephson junction stacks. When biased with dc current, the device is a typical hysteretic dc-SQUIDs with huge inductance. The inductance parameter β_L can be tuned in a wide range between 4 and 30 by changing the height and the cross-section area of the stacks. When a device was coupled with a coil and a Nb readout dc-SQUID, typical rf-SQUID behavior was observed. By applying a proper reset field, quantum escape from a single minimum has been measured on a sample of β_L∼10. The escape rate can be fine-tuned by applying short pulses down to 1 ns, which allows a fast readout technique. With these prerequisites, our experiments have opened the path to directly using these intrinsic SQUIDs as high-T_c phase qubits. The first attempts to measure Rabi oscillations on these devices will be discussed.