Observation of Photon Noise by a Parallel-Series Array of Cold-Electron Bolometers

The quasioptical qualification of cold-electron bolometers (CEB) operated in the cross-slot antenna at 350GHz, are presented. The photon noise observation by a parallel/series array of CEBs is demonstrated for power loads of the order of 1 pW. The experimental results have been fitted to theoretical model with two heat-balance equations for the absorber and for superconducting electrodes. The measured noise has been decomposed into several terms with the help of theory. It is demonstrated that the photon noise exceeds any other noise components at some voltage range, that allows us to conclude that the bolometers see the photon noise. A shape of the noise dependence on the bolometer voltage originates from the photonic component according to the theory. In the additional experiment on heating of the sample holder the photonic component is almost absent and the total noise is lower, proving the presence of the photon noise in the first experiment.