Single Photons Modulation Spectroscopy And Imaging

Quantum information technology is one of the most attractive frontiers, emerging interdisciplinary in recent years, involving many disciplines. For centuries, physicists have been trying to understand the nature of light. Single-photon generation, detection and manipulation as a strong technology supported several interesting photophysical new areas.Due to the wide range of applications of quantum information, the single photon sources have attracted great interest. On the one hand, as non classical light sources, single photon sources can be used to demonstrate the quantum mechanics basic principles, to show the singularity of quantum physics. On the other hand, quantum information technology also need to use the single-photon sources for quantum cryptography and quantum computing based on quantum mechanics,. Therefore, the preparation, measurement and manipulation of practical and reliable single-photon sources have become one of the forefront researches in quantum physics. Single photon prepared from a single quantum system is an effective means of single-photon source; we study single photon sources by light field excited single-molecule. Single-molecule system dynamics was studied by single photon modulation spectroscopy, we found many novel experimental phenomena. On this basis, the single molecule fluorescence photon intensity modulation achieved by lock-in amplifier and eliminated the quantum fluctuations of the molecular fluorescence radiation fluctuations. The high definition imaging for single SR molecule fluorescence gives an effective single molecule fluorescence imaging methods with hign signal to noise ratio. The fluorescence lifetime of the DiD molecule was measured by photon counting modulation, Manipulation the molecular fluorescence intensity by the electric field.So far, no ideal single photon source to the commercial application, usually, the weak coherent light were used to simulate the single photon source in most studies. The measurement of single-photon sources, including the sensitivity, signal to noise ratio and other key technologiesthe problem were a great distress. Single photon modulation spectroscopy and lock-in amplifier technology improved the detection efficiency of single photon detectors, significantly. The influence of quantum fluctuations was eliminated and the signal to noise ratio of weak signal detection was improved.The innovations of this paper:1. A reliable single-photon modulation technology was proposed, improved the detector efficiency of1.55μm InGaAs single photon avalanche photodiode, and restrained the background noise. The detection effiency of1.55μm wavelength can be increased1.87times than the traditional photon counting method by optimizing the threshold voltage of the detector using single photon locked technology. The possibility of highly sensitive detection in high background noise was improved; such sensitive measurements can be extended to other wavelengths of single photon detection.2. Measure the single-photon modulation spectroscopy. Single photon absorption peak of acetylene gas was measured by1.5-micron distributed feedback semiconductor laser. The high-frequency modulation of single-photon wavelength absorption spectra eliminates the background noise in low frequency. The error signal was obtained by Single-photon absorption spectroscopy of acetylene gas, the laser frequency stabilization in the175s frequency fluctuation less than25MHz.3. Single molecule fluorescence imaging without quantum fluctuations. The single-molecule fluorescence photon intensity modulation was achieved the intensity modulation of the excitation light field using acousto-optic modulator. The logic pulse signal output from single-photon detector was demodulated by lock-in amplifier. The background signal of other frequency was significantly inhibited, significantly. The signal to noise ratio of spectral imaging was improved, suppressed the quantum fluctuations from1/3to1/15, to achieve a high-resolution single-molecule fluorescence imaging, and achieved the high-definition single-molecule fluorescence imaging.4. External manipulation of single-photon source, measuring the fluorescence lifetime of the ensemble molecules and DiD molecules, studied the influence of impressed current on the fluorescence lifetime, the study found the average molecular fluorescence lifetime reduced about20%by current. The single-molecule fluorescence intensity control was achieved by external electric field modulation of single SR molecule fluorescence intensity.