Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 30: Poster: Photonics, laser development and applications, ultrashort laser pulses, quantum effects

Q 30.3: Poster

Dienstag, 18. März 2014, 16:30–18:30, Spree-Palais

Nondestructive measurement of the photon-number parity — •Mahmood Sabooni, Andreas Reiserer, Norbert Kalb, Bastian Hacker, Stephan Ritter, and Gerhard Rempe — Max-Planck Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching, Germany

Measuring the odd-even parity of the photon number plays an important role in the description of non-classical features of light. We present a novel approach towards this goal, which is based on the principles of cavity quantum electrodynamics. In our setup, a faint laser pulse is reflected off a resonant, single-sided cavity in which a single atom is trapped. When the atom is prepared in a state that does not couple to the resonator, the reflected light pulse will experience a phase shift of nπ, where n is the number of photons contained in the pulse. When the atom is prepared in a state that is strongly coupled to the cavity, there is no phase shift.

This conditional phase shift can be employed to detect the parity of the photon number when the atom is prepared in an equal superposition of the coupled and the uncoupled state: An odd number of photons in the impinging pulse will then lead to a phase flip of the atomic state, while there is no phase change when the photon number is even. Subsequent readout of the atomic phase thus allows discriminating between odd and even photon number parity. In the actual experiment we have probed the system with a weak laser pulses and then employed the parity measurement technique to nondestructively detect a single photon level probe.