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OSA Student Chapter Meeting

SPEAKER:Anton Classen
TITLE:Super-Resolution Microscopy on a Budget

In this talk I will discuss a recent Optics and Photonics News article and the corresponding paper, on using so-called upconversion nanoparticles (UCNPs) in confocal (sub-diffraction) fluorescence microscopy. Upconversion is an optical process in which lower-energy photons are converted to higher-energy photons in a step-wise manner. The fluorescence response is thus subject to a non-linearity (similar to two- and multi-photon microscopy). In the paper the authors show that their UCNPs with high Tm doping (NaYF4, doped with 20% Yb and 8% Tm) show favorable properties such as higher brightness and a maximum slope of non-linearity of up to s = 6.2.

SPEAKER:Jonathan Ben-Benjamin
TITLE:Causality in the Fermi and Scully Problems
In his review article on the quantum theory of radiation in the 1930's, Fermi presented a simple model for showcasing causality in quantum optics. Decades later, however, Shirkov noticed that Fermi had made some suspicious approximations, that when discounted, quantum theory no longer gives causal results!
Multiple camps have developed:
1. Quantum theory is the most successful theory ever devised, and since no experiment has even shown non-causal behavior, quantum mechanics done right must give causal results.
2. The reason that quantum mechanics gives non-causal results for this problem is that it is an un-physical situation. 3. The results must be non-causal.
The Scully problem is similar, in that it gives a simple model for testing causality, however, it is based in QFT in curved spacetime, and is based heavily on Unruh's and others' predictions from the 1970's for accelerating particles. In that case, many fantastic effects are predicted, some of which feature non-causality.
We show how quantum mechanics can give causal results for both the Fermi and the Scully problems..

Thursday, October 17 2019
IQSE 578, 12:30
Mitchell Physics Building

Department of Physics and Astronomy
Institute for Quantum Science and Engineering
Texas A&M University

(Pizza lunch as usual. Newcomers welcome!)

Host: Aysan Bahari