Dresden 2003 – scientific programme

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TT: Tiefe Temperaturen

TT 1: Mesoskopische Systeme I

TT 1.10: Talk

Monday, March 24, 2003, 12:00–12:15, HSZ03

Experimental investigation of persistent-current qubits — •E. Il’ichev¹, Th. Wagner¹, N. Oukhanski¹, A. Izmalkov¹, U. Hübner¹, T. May¹, H.E. Hoenig¹, H.-G. Meyer¹, M. Grajcar², D. Born², and W. Krech² — ¹IPHT e.V., 07745 Jena — ²FSU, Institut für Festkörperphysik, 07743 Jena

The proof that superconducting macroscopic systems can behave quantum-mechanically was demonstrated by several groups. Some of them are proposed to be the unit of a quantum computer. One realization is the persistent-current qubit. It consists of a superconducting loop with three Josephson junctions. We implement the impedance technique for qubit characterization. Here the qubit is inductively coupled to a high-quality tank circuit. In a first experiment the tank circuit is driven by a dc current and an ac current with a frequency close to the resonance frequency of the tank circuit. The tunneling between quantum states (Landau-Zener tunneling) was detected. In a second experiment, the qubit was irradiated with frequencies close to the level separation. By choosing the particular value of the microwave amplitude, we detected absorption and emission of low-frequency (Rabi) photons at the resonant frequency of the tank circuit.