Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 26: Transport - Poster Session

TT 26.18: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Microwave spectroscopy on single Josephson junctions — •Karl Madek, Sven Beutner, Renke Stolle, Christian Probst, Achim Marx, and Rudolf Gross — Walther-Meißner-Instiut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany

In recent years, interest in quantum computing has been continuously growing. Because of the superconducting energy gap, superconducting devices are promising candidates for qubits with sufficiently large decoherence times.

A prerequisite for the investigation of qubits is a suitable low noise experimental set-up. Performing escape rate measurements on single Josephson junctions with and without microwave irradiation is a convenient way to both test the set-up and establish the experimental methods to manipulate qubits.

Our escape temperature measurements on an SIS tunnel junction without microwave irradiation are in good agreement with theory. They show a crossover from the thermal to the quantum regime and thus prove the negligibility of system noise. In spectroscopic measurements, the junction was excited by single and multiple microwave photons, showing the quantization of the energy levels in the tilted washboard potential. From the experimental results, the intrinsic junction parameters (critical current, plasma frequency) could be determined with high accuracy. Currently, we are performing escape rate measurements on "0"- and "π" SIFS junctions.

This work was supported by the DFG through SFB 631.