Measuring decay rate of spontaneous emission from an ensemble of cold atoms by homodyne detection
Date
2018-03-06
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Abstract
Nanofibers are a valuable tool for interfacing photons with atomic media through its guided mode which propagates evanescent to the fiber. However, the nanofiber modifies the natural decay rate of the atomic dipoles due to the Purcell effect. It is vital to study these atom-fiber interactions to characterize the system. This thesis delineates an experimental technique to obtain the spontaneous emission rate of a cloud of Rubidium-87 atoms in the presence of a nanofiber. The atoms are prepared in a magneto optical trap and the emissions are monitored by balanced homodyne detection. The temporal autocorrelation function of the homodyne’s photocurrent reproduces the exponential profile of spontaneous emission. The measured time constant of the profile is 26.3 ns which is almost twice that of free space emission. The modified decay rate depends on the atom’s orientation and distance from the nanofiber surface. We theoretically estimate the modified decay rate and model the expected decay profile for our ensemble of atoms which agrees well with our measurements. To our knowledge, this is the first experimental demonstration of spontaneous emission being
measured by homodyne detection.
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Keywords
atomic fluorescence, homodyne detection, ultracold atoms, nanofiber, spontaneous emission
Citation
Jalnapurkar, S. (2018). Measuring decay rate of spontaneous emission from an ensemble of cold atoms by homodyne detection (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/22233