AntiBunched Photons emitted by a QPC – AnPhoTEQ

The present proposal aims at participating in the effort of connecting mesoscopic quantum electronics and quantum optics. More specifically, we will investigate the statistical properties of the photons emitted by the shot noise, that is the fluctuating current flowing through a DC-biased phase coherent conductor. Shot noise reflects the granularity of the charge carriers (electrons) and their probabilistic transmission through the quantum conductor. These current fluctuations result in the radiation of photons. Due to the fermionic character of the electrons, the current fluctuations are known to be sub-Poissonian, while the emitted photons have a tendency to bunch. Can one imprint this sub-Poissonian (anti-bunching) character on the radiated photons, thereby obtaining a non-classical radiation using a radically new concept (not based on atomic physics ideas)? According to a recent spectacular prediction by Beenakker and Schomerus, the answer is yes; provided that one uses a single mode quantum conductor and that the applied drain source doesn't allow a single electron to emit two photons. We propose to perform the demonstration of this prediction. In practice a Quantum Point Contact (QPC) in a 2-dimensionnal electrons gas (2DEG) will be used as an electronic beam splitter and we will study the statistics of photons emitted in the GHz range. The experimental work proposed here is based both on techniques already developed by the applicants and on innovative methods to increase the sensitivity of microwave photon detection. Those methods open new possibilities in the study of phase coherent conductors, some of which will be explored during the project. In particular, we will investigate the influence of the coupling to the electromagnetic environment on the high frequency shot noise of a QPC. We will also take advantage of the improved sensitivity to high frequency current fluctuations to measure the charge noise of a Quantum Point Contact, which results from the fluctuations of the time spent by the injected electrons in the scattering region.