We present a simple method to reconstruct the mode distribution of multimode classical and nonclassical optical fields using a single measurement of higher-order photon number correlation functions. Knowing the underlying number and structure of occupied modes of a light field plays a crucial role in minimizing loss and decoherence of quantum information. Typically, full characterization of the mode structure involves a series of several separate measurements in spatial, temporal, frequency, and polarization domains. We experimentally demonstrate reconstruction of up to three modes with excellent agreement and study the robustness of our method in experimentally realizable regimes.

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Optical sources that deterministically produce single photons with a high suppression of multi-photon emission and a negligible background component are promising candidates for standard sources for quantum metrology, quantum communication and foundations of quantum mechanics. In this paper, the photon number distribution of non-classical light emitted by nitrogen vacancy (NV) centres in nano-diamonds is studied by three different experimental techniques. The photon number resolving transition edge sensor (TES) detector and the On/Off detection method are applied to determine the diagonal elements of the optical density matrix. From the data measured by the two methods the second order correlation function at time delay zero is calculated and compared with the g 2 (0)-values obtained by Hanbury Brown-Twiss (HBT) interferometric measurements. Among the g 2 (0)-values evaluated with the three techniques, we found good agreement in the results for a single photon emitter with a g 2 (0)-value close to zero and a multi-photon source with a g 2 (0)-value of approximately 0.5.

An investigation of the breakdown of high intensity discharge (HID) lamps filled with xenon at pressures from 0.1 to 5 bar is presented. Three power supplies were used in order to provide voltage rates of increase covering about four orders of magnitude from 5 mV ns−1 to 100 V ns−1, the latter being typical for electronic ballasts driving commercial HID lamps. Customized lamps ensure a volume breakdown between the tungsten tip electrodes of the lamp. Voltage and current waveforms were measured by means of electrical probes and the transient optical radiation was captured by a fast camera system. The breakdown voltage increases with growing pressure and voltage rate up to several 10 kV. Additional UV illumination decreases the breakdown voltage and reduces its mean variation. The experimental results were reproduced with good agreement by a fluid model taking into account the electron energy balance. The model shows an ionization front propagating towards the cathode. The front moves due to continuous field compression and relies on electron avalanches initiated by secondary electrons at the cathode.

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