Single-Photon Detections And Manipulations By Weak Signals Probes

The weak light detection is one of the important scientific and technical problems in weak signal probes. Especially, single-photon detections, generations, and manipulations take the important roles in the optical quantum information processings, gravitational wave and dark matter detections, and so on.As we well know that, many approaches can be used to deliver the desired single photon emission; typically by loosing weak coherent lights through the optical attenuators, although a true single-photon source could not be delivered by this ways. Basically, the real single-photon sources should be obtained by exciting the single atoms such as artifical quantum dots. In this thesis we investigate how to generate the single photons by using the spontaneous parametric down conversion (SPDC) process through the nonlinear optical crystals. Although such a source is not a strictly single photon source as the photons statistics obey still the Poissonian distributions, it is meaningful to apply to verify the principles of quantum mechanics such as the quantum nonlocal correlations, by using the biphoton entanglements generated with the SPDC. First, with the pure-state basis assumption we test the violation of Bell inequality with a commercialized entangled source, and the value of Bell function is measured as S=2.100±0.016. Obviously, such an experimental result violate the localized theory, but is far from the maximal value:S= 2(?)2, the theoretically accessible one for a pure maximally entangled photon-pairs. In order to improve on the experimental result, we use the quantum tomographic technique to reconstructed the density matrix (the tomography's result confirm that this entangled state is really not a quantum pure entangled state). Based on this result, we give up the experimental scheme based on the suppose of pure state and propose a new scheme based on the mixed entangled state, i. e. using optimal measurement setting got from the quantum tomographic technique instead of the measurement setting related to the pure entangled state. In this way we have the value of Bell function is S=2.772±0.063, this result show that Bell's theorem is verified robustly. Later, we accomplished the experimentally testing Bell's theorem based on Hardy's nonlocal ladder proofs. The experimentally results verify the quantum nonlocality robustly again.On the side of single photon detection, we focus our attention on superconducting detectors for its good performance. These detectors work at low temperature bellow 1 K has low noise and high quantum efficiency, which make them attractive. They are powerful detectors in a broad wavelength range, and have make great progress in recent decades. We introduce two kinds of superconducting detectors, Transition Edge Sensor(TES) and superconducting microwave resonator. A TES works in the narrow temperature around its superconducting transition temperature, the resistance will change after the energy is absorbed by film. And superconducting microwave resonator can be called as quasiparticle detector, a photon which breaks Cooper pairs in the superconducting film will create the quasiparticles. The surface impedance is influenced by these additional quasiparticles, and the resonance frequency moves when the kinetic inductance changes. On TES's side, we attempt to fabricate the TES using the tungsten film. After we get the TES sample we made, we measure and analyze the transition temperature of TES. We build a circuit in the dilution refrigerator in order to get the resistance (R-T curve). These works lay a foundation for further research on TES. In the research of superconducting microwave resonator, we build a low noise microwave IQ measuring system on the foundation of ?/4 resonator. This make us realize the time domain measurement and we have realized the photon-counting detector based on MKID. On this basis, it will provide the detection of dark matter, comic microwave background, nuclear radiation, gravitational waves and other forefront of science technical support.The last work of this paper is about manipulation of atomic coherence. We find that when atoms dispersively coupled to a driven cavity, we can control photon bunching by adjusting the atomic superposition.Finally, the paper summarizes the study of my studies on the field on single photon detection and manipulation.