Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 8: Transport: Quantum Coherence and Quantum Information Systems 1 (jointly with TT, MA)

HL 8.5: Talk

Monday, March 26, 2012, 10:30–10:45, BH 243

Observation of the Geometric Phase of a Harmonic Oscillator in Circuit Quantum Electrodynamics — •Stefan Filipp, Marek Pechal, Simon Berger, Abdufarrukh A. Abdumalikov, and Andreas Wallraff — ETH Zurich, Department of Physics, 8093 Zurich, Switzerland

Transporting a quantum harmonic oscillator state along a closed path in Hilbert space leads to a path-dependent geometric phase. However, the linearity of the system precludes its observation without a non-linear quantum probe. We therefore make use of a superconducting qubit serving as an interferometer to measure the geometric phase of a harmonic oscillator realized as an on-chip transmission line resonator [1]. We demonstrate the proportionality of the geometric phase to the enclosed area for a variety of path shapes. At the transition to the non-adiabatic regime, we analyze corrections to the geometric phase and show how entanglement between the two-level system and the harmonic oscillator leads to dephasing. This system provides a versatile tool to study adiabatic and non-adiabatic geometric phases in open quantum systems and as a resource for quantum information processing.
M. Pechal, S. Berger, A.A. Abdumalikov, A. Wallraff and S. Filipp, arxiv:1109.1157 [quant-ph] (2011)