Hannover 2016 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 57: Quantum Effects: QED II
Q 57.3: Vortrag
Donnerstag, 3. März 2016, 15:15–15:30, f442
Quantum decoherence of a single-ion qubit induced by single optical photons — •Moonjoo Lee1, Konstantin Friebe1, Florian R. Ong1, Dario A. Fioretto1, Bernardo Casabone1, Klemens Schueppert1, Rainer Blatt1,2, and Tracy E. Northup1 — 1Institute of Experimental Physics, University of Innsbruck, Austria — 2Institute of Quantum Optics and Quantum Information, Austria
Quantum measurement is based on the interaction between a quantum object and a meter entangled with the object. While the information stored in the object is being extracted by the interaction, the measurement leads to decoherence of the object due to the intrinsic quantum fluctuations of the meter. Here, we report the observation of measurement-induced dephasing of a single-ion qubit with single optical photons. We employ a single 40Ca+ ion that is dispersively coupled to a high-finesse cavity. The cavity is driven by a weak laser field to populate the cavity with mean photon numbers up to five. Spectroscopy is performed on the 729 nm qubit transition to identify the shift and broadening of the atomic energy levels. The information stored in the qubit is extracted by photons escaping the cavity, which, in turn, leads to dephasing of the qubit owing to photon-number fluctuations. This measurement represents the first demonstration of such quantum decoherence effects in the optical domain. Furthermore, heterodyne measurements of the cavity output photons will make it possible to probe quantum trajectories of the qubit nondestructively.