The surface dynamics of supercooled liquid-glycerol is studied by scanning the thickness of the glycerol film with single photon detection.Measurements are performed at room temperature well above the glycerol's glass transition temperature.It is shown that the surface dynamics of the glycerol film is very sensitive to the temperature.The linear relationship between the thickness of the film and the viscosity predicted by the Vogel-Fulcher-Tammann-Hesse(VFTH) law is also presented experimentally.
We report on the observation of enhanced high-order partial wave scattering from atom–atom interaction via changing the temperature of a magneto–optical trap in the process of photoassociation. The high-order scattering partial wave is directly manifested through the large signal amplitude of the rovibrational resonance levels of trap-loss spectroscopy from photoassociation.
A method of locking the relative phase to provide stable constructive or destructive interference between the phase-modulated sidebands from a pair of phase modulators is demonstrated. It is discussed theoretically for optimal fringe visibility related to the phase noise from faulty system. After phase locking using the phase modulating and lock-in technique,the drift of the relative phase is focalized around ±0.0016 rad and the fringe visibility is restricted to 2×10-4 .
The quantum fluctuation of photon counting limits the field application of optical time domain reflection. A method of photon counts modulation optics time domain reflection with single photon detection at 1.55 μm is presented. The influence of quantum fluctuation can be effectively controlled by demodulation technology since quantum fluctuation shows a uniform distribution in the frequency domain. Combined with the changing of the integration time of the lock-in amplifier, the signal to noise ratio is significantly enhanced. Accordingly the signal to noise improvement ratio reaches 31.7 dB compared with the direct photon counting measurement.
Loading time is one of the most important dynamic characteristics of a magneto-optical trap.In this paper,we primarily report on a detailed experimental study of the effects of some magneto-optical trap control parameters on loading time,including the background vacuum pressure,the magnetic field gradient,and the intensities of trapping and repumping lasers.We compare the results with previous theoretical and experimental results,and give qualitative anal-ysis.These experimental investigations offer some useful guidelines to control the loading time of magneto-optical traps.The controllable loading time achieved is helpful to enhance the signal-to-noise ratio of photoassociation spectroscopy,which is remarkably improved from 7 to 28.6.
