Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 32: Transport: Quantum Coherence and Quantum Information Systems - Part 2

TT 32.8: Talk

Thursday, March 30, 2006, 16:00–16:15, HSZ 304

Observation of Rabi oscillations in a phase qubit — •J. Lisenfeld¹, A. Lukashenko¹, S. Shitov², and A.V. Ustinov¹ — ¹Physikalisches Institut III, Universität Erlangen, Germany — ²Institute of Radio Engineering and Electronics, Moscow, Russia

Quantum bits based on superconducting tunnel junction circuits are promising candidates to realize solid-state quantum computation. A phase qubit is formed from an rf-SQUID, whose Josephson phase eigenstates are used as logical states [1]. Those are mapped to macroscopically distinct flux states in the readout process, which is based on quantum tunneling stimulated by a short pulse of magnetic flux.

We experimentally demonstrate the preparation of an arbitrary quantum state in such a system, which has been fabricated using our design at a standard foundry. Rabi oscillation, a spectroscopic measurement of the dephasing time and evidence of qubit coupling to parasitic resonators are presented. From upcoming data on the temperature dependence of decoherence processes we hope to clarify whether the observed Rabi-type oscillations, alternatively, originate from a classical junction dynamics in the microwave field [2].

[1] R.W. Simmonds et al., Phys. Rev. Lett. 93, 077003 (2004)

[2] N. Grønbech-Jensen and M. Cirillo, Phys. Rev. Lett. 95, 067001 (2005)