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“ Science is a way of thinking much more than it is a body of knowledge. ”
- Carl Sagan
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Physics Conference Room, SB B326
Coffee starts at 12:00 PM and talk starts at 12:15 PM
6
Sep '17
David Petiteau  -  Wednesday, September 6, 2017
25
Sep '17
Viviana Acquaviva  -  Monday, September 25, 2017
Understanding the Universe through distant galaxies
New York City College of Technology
ABSTRACT: Understanding the physical properties of galaxies and their evolution through cosmic time means learning more about the Hubble expansion, gravity, and the physical mechanisms that regulate the growth of structures. My work focuses on developing and using better tools to extract maximal information from ongoing and future data from large galaxy surveys, such as CANDELS and LSST. I will present my efforts at improving our ability to determine galaxy properties through Spectral Energy Distribution (SED) fitting. I will introduce GalMC and SpeedyMC, the Markov Chain Monte Carlo algorithms for SED fitting I created, and show how they can be used to recover the age, mass, dust content, metallicity and star formation history of galaxies, as well as to jointly determine photometric redshifts and SED fitting parameters. If time allows it, I will describe the science goals of the Hobby Eberly Telescope Dark Energy eXperiment (HETDEX), which is set to discover several hundred thousand Lyman Alpha Emitting galaxies at 2 < z < 3.5 and use them to shed light on the behavior of dark energy and gravity in this largely unexplored redshift range, and summarize our recent efforts in optimizing the sample selection using Bayesian statistics and machine learning techniques.
2
Oct '17
Sarang Gopalakrishnan  -  Monday, October 2, 2017
ABSTRACT: Electronic wave functions in quasiperiodic systems are intermediate between those in crystalline and random systems. Quasiperiodic systems exhibit Anderson localization, but the properties of the localized state and the localization transition are different from those in random systems. We explore various distinctive aspects of localization in quasiperiodic systems, including a multicritical point in quasiperiodic models with power-law hopping and a semimetal-to-metal phase transition in quasiperiodic Dirac materials.
16
Oct '17
Vipin Kerala Varma  -  Monday, October 16, 2017
ABSTRACT: In this talk we report on the response of (quasi)disordered spin-chains to boundary driving through reservoirs at its ends. In the nonequilibrium current-carrying states, anomalous transport rates of spins are shown to be harbored in noninteracting quasidisordered systems at criticality, and far from criticality in the interacting system; in addition, these steady states exhibit spatial fractality in many of its expectation values, opening an alternative route to experimentally probe a system's fractal properties in contrast to measuring quantum wavefunctions.
23
Oct '17
Alexander Granovsky  -  Monday, October 23, 2017
30
Oct '17
Stephen Arnold  -  Monday, October 30, 2017
Opto-mechanics: fabrication of nano and micro-optic sensors
Polytechnic Institute of New York University
8
Nov '17
Daniel Kabat  -  Wednesday, November 8, 2017
13
Nov '17
Michael Mirkin  -  Monday, November 13, 2017
20
Nov '17
Andrew Kent  -  Monday, November 20, 2017
28
Nov '17
Roman Kezerashvili  -  Tuesday, November 28, 2017
ABSTRACT: A study the formation of a spatially indirect exciton as a pair of an electron and a hole in two layers of gapped graphene, or transition metal dichalcogenide (TMDC), or phosphorene separated by a dielectric is presented. A solution of two-body problem in these systems is discussed. We propose to observe the superfluidity and Bose-Einstein condensation for a quasi-two-dimensional gas of indirect excitons in these quantum heterostructures. The superfluidity of 2D spatially indirect excitons at low densities in TMDC double layers form a two-component weakly interacting gas of A and B excitons. We demonstrate that the mean field critical temperature for a two-component dilute weakly interacting Bose gas of excitons in a TMDC double layer is an increasing function of the factor Q, determined by the effective reduced mass of A and B excitons. We predict that a weakly interacting gas of dipolar excitons in a double layer of phosphorene exhibits superfluidity and show that the critical velocity of superfluidity, the spectrum of collective excitations and mean field critical temperature for superfluidity are anisotropic and depend on the direction of motion of dipolar excitons.