Department Calendar

Week of February 18, 2018

  Sun Mon Tue Wed Thu Fri Sat
All day
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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"Quantum Focusing and the Quantum Null Energy Condition"

"Quantum Focusing and the Quantum Null Energy Condition"

Date: 
Mon, 02/19/2018 - 2:10pm
Location: 
Pupin Hall Theory Center, 8th Floor

Raphael Bousso

University of California, Berkeley

"Quantum Focusing and the Quantum Null Energy Condition"

The study of black holes has revealed a deep connection between quantum information and spacetime geometry. Its origin must lie in a quantum theory of gravity, so it offers a valuable hint in our search for a unified theory. Precise formulations of this relation recently led to new insights in Quantum Field Theory, some of which have been rigorously proven. An important example is our discovery of the first universal lower bound on the local energy density. The energy near a point can be negative, but it is bounded below by a quantity related to the information flowing past the point.

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02/19/2018 - 2:10pm
 
 
 
"The Social Life of Heavy Quarks"

"The Social Life of Heavy Quarks"

Date: 
Mon, 02/19/2018 - 4:15pm
Location: 
428 Pupin Hall

Marek Karliner

Tel-Aviv University

"The Social Life of Heavy Quarks"

I will discuss recent developments regarding new types of hadrons involving heavy quarks: hadronic molecules, doubly heavy baryons, stable tetraquarks and others. I will also explain how the discovery of the doubly heavy baryon leads to quark-level analogue of nuclear fusion, with energy release per reaction an order of magnitude greater than in ordinary fusion.

About the speaker

Marek Karliner was born in Poland in 1955 and arrived in Israel in 1969. He received his B.Sc. in physics in 1979 and his Ph.D. in 1984 (with Prof. David Horn), both from Tel Aviv University. As a graduate student he spent one year at Stanford University as Fulbright Fellow. Between 1984 and 1988 he was a Chaim Weizmann Postdoctoral Fellow and then a Research Associate at the Stanford Linear Accelerator Center. In 1988 the Higher Education Council of Israel awarded him the Alon Fellowship for Outstanding Junior Faculty and subsequently he joined TAU School of Physics and Astronomy as a senior lecturer. At TAU he has been a Professor of Physics since 1995 and also served as Chairman of Particle Physics Department in 2006-2010 and Chairman of the Raymond and Beverly Sackler Institute of Theoretical Physics in 2010-2015. Karliner's research is in the field of theoretical physics of elementary particles. He is incumbent on the Edouard and Francoise Jaupart Chair of Theoretical Physics of Particles and Fields. In 2003-2005 he was a Visiting Professor at the Cavendish Laboratory, University of Cambridge. Since 2017 he has been a Foreign Member of the Polish Academy of Arts and Sciences. 

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02/19/2018 - 4:15pm
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
"Probing gravity with macroscopic quantum states"

"Probing gravity with macroscopic quantum states"

Date: 
Tue, 02/20/2018 - 12:15pm
Location: 
705 Pupin Hall

Peter Asenbaum

Stanford University

"Probing gravity with macroscopic quantum states"

Freely falling particles are ideal test masses to study gravitational interactions. We use light pulse interferometry to study the propagation of ultra-cold atoms in free fall. So far quantum experiments have been carried out in locally flat space and can be summarized as testing the equivalence principle. Precision tests of the equivalence principle do not only test the geometrical nature of gravity but also serve as extraordinarily sensitive probes for new, ultra-weak interactions. Our current efforts focus on a test of the weak equivalence principle at the 10-13 level with two rubidium isotopes. We suppress gravity gradient systematic errors to below one part in 1013 and demonstrate a relative precision of Δg/g≈3×10−11 per shot, which improves the state of the art the best previous result for a dual-species atom interferometer by more than three orders of magnitude [1]. 

With the help of the large momentum transfer techniques [2] we can now create macroscopic quantum states on the order of tens of cm. The large spatial extent allows us to go beyond the equivalence principle and observe genuine gravity effects in a quantum system [3]. 

[1]  Effective inertial frame in an atom interferometric test of the equivalence principle
      C. Overstreet, P. Asenbaum, T. Kovachy, R. Notermans, J. M. Hogan, M. A. Kasevich
      arXiv:1711.09986 (2017)
 
[2]  Quantum superposition at the half-meter scale
      T. Kovachy, P. Asenbaum, C. Overstreet, C. A. Donnelly, S. Dickerson, A. Sugarbaker, J. Hogan, M. Kasevich 
      Nature 528, 530–533 (2015)
 
[3]  Phase shift in atom interferometry due to spacetime curvature across its wave function
      P. Asenbaum, C. Overstreet, T. Kovachy, D.D. Brown, J. M. Hogan, and M. A. Kasevich
      Phys. Rev. Lett. 118, 183602 (2017)
 
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02/20/2018 - 12:15pm
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
"Control and Local Measurement of the Spin Chemical Potential in a Magnetic Insulator"

"Control and Local Measurement of the Spin Chemical Potential in a Magnetic Insulator"

Date: 
Thu, 02/22/2018 - 12:15pm
Location: 
705 Pupin Hall

Chunhui Du

Harvard University
"Control and Local Measurement of the Spin Chemical Potential in a Magnetic Insulator"

In recent decades, a large scientific effort has focused on harnessing spin transport for providing insights into novel materials and low-dissipation information processing. We introduce single spin magnetometry based on nitrogen-vacancy (NV) centers in diamond as a new and generic platform to locally probe spin chemical potentials which essentially determine the flow of spin currents. We use this platform to investigate magnons in a magnetic insulator yttrium iron garnet (YIG) on a 100 nanometer length scale. We demonstrate that the local magnon chemical potential can be systematically controlled through both ferromagnetic resonance and electrical spin excitation, which agrees well with the theoretical analysis of the underlying multi-magnon processes. Our results open up new possibilities for nanoscale imaging and manipulation of spin-related phenomena in condensed-matter systems.

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02/22/2018 - 12:15pm
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Guy Sella, Columbia Systems Biology

Guy Sella, Columbia Systems Biology

Date: 
Fri, 02/23/2018 - 11:00am
Location: 
Pupin Hall Theory Center, 8th floor

Guy Sella

Columbia Systems Biology

Title TBA

Guy Sella is an associate professor in the Columbia University Department of Biological Sciences and a member of the Center for Computational Biology and Bioinformatics. His lab studies the evolutionary processes that give rise to genetic and phenotypic differences between individuals, populations, and closely related species. They use mathematical models to better understand these processes, and statistical analyses to identify their footprints in data and make inferences about them. Current work in the lab focuses primarily on the evolutionary causes of adaptation and disease, but also on a variety of other topics. Before joining Columbia, Sella was a faculty member at Hebrew University (Israel) and a visiting professor at Stanford University.

https://systemsbiology.columbia.edu/faculty/guy-sella

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02/23/2018 - 11:00am
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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