Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 26: Transport - Poster Session

TT 26.21: Poster

Wednesday, March 29, 2006, 14:30–18:30, P1

Coupled Josephson Phase Qubits — •T. Wirth¹, J. Lisenfeld¹, A. Lukashenko¹, S. Shitov², and A.V. Ustinov¹ — ¹Physikalisches Institut III, Universität Erlangen, Germany — ²Institute of Radio Engineering and Electronics, Moscow, Russia

Solid-state quantum bits based on current-biased Josephson junctions have recently been shown as very promising. They require appropriate isolation from the bias leads which can be achieved by the use of superconducting transformers. The resulting rf-SQUID has a double-well potential, where the discrete quantum levels in one well can be used as qubit states. State-dependent tunneling to the other well changes the magnetic flux in the qubit, which is measured by a dc-SQUID. We experimentally demonstrate the preparation of an arbitrary quantum state using nanosecond long microwave pulses and observe Rabi oscillations using samples fabricated by a standard foundry. Another crucial point is the coupling of qubits, which we currently study in a system of two capacitively coupled flux-biased phase qubits. Our ongoing experiments are focused on spectroscopic measurements of the coupling strength and the demonstration of coherent interaction in the time domain by observing antiphase oscillation of the two-qubit states at the degeneracy point.