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Physics Colloquium - Graduate Student Presentations

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Thursday, February 3, 2022 4 pm to 5 pm

This is a past event.

Thursday, February 3rd @ 4pm – Fisher Hall 139 & Zoom

Hybrid-Mode: The students will give their talks in Fisher Hall 139. Please join in-person or by zoom.

Lucas Simonon  

[Advisor: Ramy El-Ganainy]

Quantum Noise in Optical Amplifiers Operating at Exceptional Points

The concept of exceptional points-based optical amplifiers (EPOAs) has been recently proposed as a new paradigm for miniaturizing optical amplifiers while simultaneously enhancing their gain-bandwidth product. While the operation of this new family of amplifiers in the classical domain provides a clear advantage, their performance in the quantum domain has not yet been evaluated. Particularly, it is not clear how the quantum noise introduced by vacuum fluctuations will affect their operation.

We investigate this problem by considering three archetypal EPOAs structures and use the Heisenberg-Langevin formalism to calculate the added quantum noise in each of these devices. Our analysis reveals several interesting results: (1) The output noise level exceeds that of quantum-limited amplifiers; (2) The noise level does not follow a universal dependence on the order of the exceptional point but rather varies from one implementation to another.


Sam Groetsch  

[Advisor: Jacek Borysow]

Application of Argon Pressure Broadened Rubidium Vapor Cells as Ultra-Narrow Notch Filters

Raman spectroscopy is a widely used, highly versatile, and non-destructive method for characterizing the molecular makeup of unknown samples. In nearly all applications the vibrational modes of the constituent molecules provide the mechanism by which the laser light is inelastically scattered and consequently identified. However, the rotational modes of these molecules provide much greater relative rates of inelastic scattering than the vibrational modes. Unfortunately, due to the nature of current filters used in Raman spectroscopy when the laser light is filtered out so to is the light scattered by the pure rotational modes. In this research we propose the use of a Rubidium vapor cell filled with a buffer gas of Argon as a viable ultra-narrow notch filter. This filter would provide a robust laser rejection without removing the light scattered by the pure rotational modes of molecules. Measurement of the pure rotational spectrum of gases can have numerous applications such as precision measurement of exhaled gases for medical diagnostics, highly accurate remote measurement of atmospheric temperatures, and extremely sensitive detection of dangerous air contamination in dusty environments.

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