Physics Evaluation of Features in Rubidum-87 Optical Pumping Measurements Cooper Billiter Project Mentor(s): Michael Braunstein, PhD The purpose of this project is to evaluate features observed in measurements made using an apparatus that optically pumps rubidium. It is hypothesized that these features are a result of quadratic Zeeman splitting in the D1 line ( 5 2 𝑆𝑆 1 / 2 → 5 2 𝑃𝑃 1 / 2 ) of rubidium-87. A rubidium lamp was used to excite a cell of rubidium into a pumped state. A static magnetic field varied the Zeeman splitting of the rubidium atom energy states in the cell, while a radio frequency (RF) electromagnetic field was applied to the cell. When the Zeeman splitting matched the photon energy of this RF field, rubidium atoms transitioned out of the pumped state. This effect can be observed, and the RF field frequency at which it occurs can be related to the Zeeman splitting. The Breit-Rabi formula was applied to determine if the features observed are consistent with quadratic Zeeman splitting. Presentation Type: Oral Presentation (May 20, 9:30am–5:00pm) Keywords: optical pumping, Zeeman splitting SOURCE Form ID: 91 For this project, we developed methods for the Python control of instrumentation for biphoton experiments. Biphoton experiments are a method for characterizing the behavior of single photons and are foundational to quantum mechanics. To achieve this, photons from a pump laser underwent spontaneous parametric down conversion (SPDC) resulting in a biphoton for which one was designated as signal and the other as idler. These photons were then detected using two avalanche photodiodes (APD), one for signal photon detection and the other for idler photon detection. The idler photons triggered a start event on a time-to-amplitude converter (TAC) and the signal photons triggered a stop event. A time-delay was introduced to the signal photon detection with the use of a long coaxial cable between the APD and TAC. If the time difference between the start and stop events matched the time- delay, then those signal and idler photons were coincidences, thus confirming they were a biphoton. A Python environment and code was developed to control a NI-DAQmx counting module that was able to count each signal photon, idler photon, and coincidence from the TAC. The results of this project are a developed Python code and method that gives normalized photon count values that correct for any drift in pump laser output and allows the measurement of the degree of the second order coherence. Presentation Type: Poster Presentation (May 21, 9:30am–3:00pm) Keywords: biphoton, Python control of NI counters, second order coherence SOURCE Form ID: 141 Development of Methods for Biphoton Measurements Noah Bragg Project Mentor(s): Michael Braunstein, PhD
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