Colloquium Schedule

Colloquium: Thursday, August 30, 4:10 PM, Lewis Lab 316

Random Numbers from Light: Photons, Chaos and Entropy

Rajarshi Roy

Department of Physics
University of Maryland

Many physical processes, including the intensity fluctuations of a chaotic laser, the detection of single photons, and the Brownian motion of a microscopic particle in a fluid are unpredictable, at least on long timescales. This unpredictability can be due to a  variety of physical mechanisms, but it is quantified by an entropy rate. This rate, which describes how quickly a system produces new and random information, is fundamentally important in statistical mechanics and practically important for random number generation. We experimentally study entropy generation and the emergence of deterministic chaotic dynamics from discrete noise in a system that applies feedback to a weak optical signal at the single-photon level. We show that in this system the dynamics transition from shot noise to chaos as the photon rate increases and that the entropy rate can reflect either the deterministic or noisy aspects of the system depending on the sampling rate and resolution of the measurements.

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Physics and Astronomy Colloquia are usually scheduled for Thursdays at 4:10 PM in Lewis Lab room 316. Refreshments and snacks are available in the nearby coffee room at 3:45 PM.


Physics Colloquium Schedule for FALL 2018

Click on Title below for past or upcoming Announcements (where available), and Speaker name for website.        

August 30Rajarshi RoyUniv. of MarylandRandom Numbers from Light: Photons, Chaos and Entropy
September 6Markus LutyUC DavisMapping the Landscape of Quantum Field Theories
September 13Oana JurchescuWake Forest Univ.-
September 20---
September 27Ryan PensackBoise State Univ.-
October 4Steven GubserPrinceton Univ.Number Theory and Spacetime
October 11---
October 18John ThomasN. Carolina StateScale Invariant Strongly Interacting Fermi Gases
October 25---
November 1Feyman Symp.--
November 8---
November 15Christopher PopeTexas A&M-
November 22No ColloquiumHappy Thanksgiving-
November 29Taviare HawkinsU. Wisconsin-
December 6François NedelecEMBL HeidelbergActive Contraction or Expansion of Disordered Cytoskeletal Networks
December 11---