Hamburg 2009 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 18: Quanteninformation: Photonen I

Q 18.5: Talk

Tuesday, March 3, 2009, 11:30–11:45, VMP 6 HS-D

Characterisation of single photons by photon counting — •Kaisa Laiho, Malte Avenhaus, Katiuscia N. Cassemiro, and Christine Silberhorn — Max Planck Research Group, Günther-Scharowsky-Str. 1/Bau 24, 91058 Erlangen, Germany

Photon counting offers a possibility for direct characterisation of quantum states, and it can be utilised especially in the study of non-Gaussian states. This method is based on the measurement of the averaged photon number parity. The information about the coherences of the state is recovered by investigating the behaviour of the displaced states.

We study the direct characterisation of single photons with recently developed time-multiplexed detection (TMD) of photon statistics. According to our numerical simulations TMD is suitable for state characterisation even in the regime of low detection efficiency and the state reconstruction is possible with good accuracy [1].

We study the preparation of single photons in a waveguided parametric down conversion source in the ultrafast regime. Our experimental results indicate tight spectral correlations between signal and idler. Due to simultaneous excitation of several broadband spectral modes we apply filtering at the state preparation. In order to decorrelate the state and to meet the high demands set by the sensitivity of the characterisation method we employ a filter with 0.7nm bandwidth at the trigger arm. At low power regime our heralded statistics show one photon component of 95% with the preparation rate of 60Hz.

[1] K. Laiho et al., arXiv:quant-ph/0811.0284 (2008).