Department Calendar

April 2018

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HEP Seminar: Allen Caldwell, Max Planck

HEP Seminar: Allen Caldwell, Max Planck

Date: 
Mon, 04/02/2018 - 12:30pm
Location: 
705 Pupin Hall

*Special day & time:  Monday, April 2, 2018, 12:30 PM*

"Accelerating Electrons with Protons in Plasma - the AWAKE Project"

Allen Caldwell

Max Planck Institute for Physics, Munich

The construction of ever larger and costlier accelerator facilities has its limits, and new technologies will be needed to push the energy frontier. Plasma Wakefield acceleration is a rapidly developing field and is a promising candidate technology for future high-energy accelerators. The AWAKE collaboration is pursuing an approach to accelerate electrons to the TeV energy regime in a plasma. To verify this novel technique, a proof-of-principle demonstration experiment is being carried out using 400 GeV proton beams from the Super Proton Synchrotron at CERN.  First results from the experiment will be presented, as well as ideas on future applications of this technology.

 

* Lunch will be available

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04/02/2018 - 12:30pm
 
Theory Seminar: Oliver Janssen, NYU

Theory Seminar: Oliver Janssen, NYU

Date: 
Mon, 04/02/2018 - 2:10pm
Location: 
Pupin Hall Theory Center, 8th Floor

"The no-boundary proposal: alive and well"

Oliver Janssen

New York University

It has recently been argued that the no-boundary proposal — a suggestion for the “wave function of the universe” due to Hartle & Hawking — is mathematically ill-defined, in the sense that a consistent implementation of it in terms of a path integral is impossible (Feldbrugge et al., PRD 95 103508, PRL 119 171301 & PRD 97 023509). This is purportedly due to singular, off-shell contributions to the path integral which would render large perturbations in de Sitter space unsuppressed. The discovery of these contributions would be made possible by a mathematical device, “Picard-Lefschetz theory”. I will point out the flaws in the logic leading to these conclusions, and argue that the no-boundary proposal does have a consistent formulation leading to physically reasonable predictions in cosmology, that singular/off-shell configurations are irrelevant and that Picard-Lefschetz theory is a red herring.

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04/02/2018 - 2:10pm
 
Colloquium: Kate Scholberg, Duke

Colloquium: Kate Scholberg, Duke

Date: 
Mon, 04/02/2018 - 4:15pm
Location: 
428 Pupin Hall

“Detecting the Tiny Thump of the Neutrino”

Kate Sholberg

Duke University

Neutrinos interact only rarely with matter.  Coherent elastic neutrino-nucleus scattering (CEvNS) was first predicted in 1974; it’s a process in which a neutrino scatters off an entire nucleus.  By neutrino standards, CEvNS occurs frequently, but it is tremendously challenging to see. The only way to observe it is to detect the minuscule thump of the nuclear recoil.  CEvNS was measured for the first time by the COHERENT collaboration using the unique, high-quality source of neutrinos from the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory.  This talk will describe COHERENT's recent measurement of CEvNS, the status and plans of COHERENT's suite of detectors at the SNS, and the physics we will learn from the measurements.

About the speaker

Kate Scholberg received a B.Sc. in Physics from McGill University in 1989 and a Ph.D. from Caltech in 1997 for thesis research on the MACRO (Monopole, Astrophysics and Cosmic Ray Observatory) experiment located at the Gran Sasso Laboratory in Italy. She was a research associate at Boston University and an assistant professor at MIT before moving to Duke University in 2004.

Her main specific interests are in neutrino physics: she studies neutrino oscillations with the Super-Kamiokande experiment, a giant underground water Cherenkov detector located in a mine in the Japanese Alps. Super-K was constructed to search for proton decay and to study neutrinos from the sun, from cosmic ray collisions in the atmosphere, and from supernovae. On Super-K, Prof. Scholberg's primary involvement is with the atmospheric neutrino data analysis, which in 1998 yielded the first convincing evidence for neutrino oscillation (implying the existence of non-zero neutrino mass).

More details on Kate Scholberg's research can be found here.

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04/02/2018 - 4:15pm
 
 
CM / AMO Seminar: Massimiliano Di Ventra, UCSD

CM / AMO Seminar: Massimiliano Di Ventra, UCSD

Date: 
Wed, 04/04/2018 - 11:30am
Location: 
705 Pupin Hall

**Special day & time**

"MemComputing: a brain-inspired topological computing paradigm"

Massimiliano Di Ventra

Department of Physics, University of California San Diego

Which features make the brain such a powerful and energy-efficient computing machine? Can we reproduce them in the solid state, and if so, what type of computing paradigm would we obtain? I will show that a machine that uses memory to both process and store information, like our brain, and is endowed with intrinsic parallelism and information overhead - namely takes advantage, via its collective state, of the network topology related to the problem - has a computational power farbeyond our standard digital computers [1]. We have named this novel computing paradigm “memcomputing” [2, 3]. As examples, I will show the polynomial-time solution of prime factorization, the search version of the subset-sum problem [4], and approximations to the MaxSAT beyond the inapproximability limit [5] using polynomial resources and self-organizing logic gates, namely gates that self-organize to satisfy their logical proposition [4]. I will also demonstrate that these machines are described by a Witten-type topological field theory, and they compute via an instantonic phase, implying that they are robust against noise and disorder [6]. The digital memcomputing machines that we propose can be efficiently simulated, are scalable and can be easily realized with available nanotechnology components, and may help reveal aspects of computation of the brain. Work supported in part by MemComputing, Inc. (http://memcpu.com/).

[1] F. L. Traversa and M. Di Ventra, Universal Memcomputing Machines, IEEE Transactions on Neural Networks and Learning Systems 26, 2702 (2015).
[2] M. Di Ventra and Y.V. Pershin, Computing: the Parallel Approach, Nature Physics 9, 200 (2013).
[3] M. Di Ventra and Y.V. Pershin, Just add memory, Scientific American 312, 56 (2015).
[4] F. L. Traversa and M. Di Ventra, Polynomial-time solution of prime factorization and NP-complete problems with digital memcomputing machines, Chaos: An Interdisciplinary Journal of Nonlinear Science 27, 023107 (2017).
[5] F. L. Traversa, P. Cicotti, F. Sheldon, and M. Di Ventra, Evidence of an exponential speed-up in the solution of hard optimization problems, arXiv:1710.09278.
[6] M. Di Ventra, F. L. Traversa and I.V Ovchinnikov, Topological field theory and computing with instantons, Annalen der Physik 1700123 (2017).

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04/04/2018 - 11:30am
 
HEP Seminar: Maggie Tse, MIT

HEP Seminar: Maggie Tse, MIT

Date: 
Wed, 04/04/2018 - 1:00pm
Location: 
705 Pupin Hall

"Quantum Noise Reduction in Advanced LIGO Using Squeezed Vacuum States"

Maggie Tse

Massachusetts Institute of Technology

Squeezed vacuum injection, also known as "squeezing", is an upgrade for Advanced LIGO that is currently underway. By injecting squeezed vacuum states through the dark port of the interferometer, quantum noise can be reduced. For this upgrade, the goal is to achieve a 3dB quantum noise reduction above 100 Hz, where shot noise limits the Advanced LIGO sensitivity. This would improve the detector high-frequency sensitivity by a factor of sqrt(2), with negligible degradation at lower frequencies. In this talk I will give an overview of squeezing, the astrophysical implications of improving the detector's high-frequency performance, an update on the progress of the Advanced LIGO upgrade, and a look into future prospects.

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04/04/2018 - 1:00pm
 
 
 
 
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Theory seminar: Lisa Randall, Harvard

Theory seminar: Lisa Randall, Harvard

Date: 
Mon, 04/09/2018 - 2:10pm
Location: 
Pupin Hall Theory Center, 8th floor

"Calculating Eccentricity in Black Hole Binary Mergers"

Lisa Randall

Harvard University

About the speaker

Professor Lisa Randall studies theoretical particle physics and cosmology at Harvard University. Her research connects theoretical insights to puzzles in our current understanding of the properties and interactions of matter. She has developed and studied a wide variety of models to address these questions, the most prominent involving extra dimensions of space. Her work has involved improving our under-standing of the Standard Model of particle physics, supersymmetry, baryogenesis, cosmological inflation, and dark matter. Randall’s research also explores ways to experimentally test and verify ideas and her current research focuses in large part on the Large Hadron Collider and dark matter searches and models.

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04/09/2018 - 2:10pm
 
Colloquium: Lindley Winslow, MIT

Colloquium: Lindley Winslow, MIT

Date: 
Mon, 04/09/2018 - 4:15pm
Location: 
428 Pupin Hall

"Axion Dark Matter and Neutrinoless Double-Beta Decay: New Techniques for New Physics"

Lindley Winslow

Massachusetts Institute of Technology

Two of the biggest open questions in the Standard Model of Particle Physics are: is the neutrino its own antiparticle, a Majorana particle and is PQ Symmetry and the resulting axion the solution to the strong CP problem. The answer to these questions is a portal to new physics and the answer to the even bigger questions of the generation of the matter-antimatter asymmetry and the nature of dark matter. My group works to address these questions with searches for neutrinoless double-beta decay and ultra-light axions. In this talk, I will review the physics that connects these two efforts, the current status of the fields, and our R&D efforts towards the next-generation experiments.

The neutrino is unique among the Standard Model particles. It is the only fundamental fermion that could be its own antiparticle, a Majorana particle. A Majorana neutrino would acquire mass in a fundamentally different way than the other particles and this would have profound consequences to particle physics and cosmology. The only feasible experiments to determine the Majorana nature of the neutrino are searches for the rare nuclear process neutrinoless double-beta decay.  CUORE uses tellurium dioxide crystals cooled to 10 mK to search for this rare process.  In this talk, I will present the first results from this detector and highlight my group’s R&D efforts and our other efforts including axions and nanoparticle-based liquid scintillators.

About the speaker

Lindley Winslow is an experimental nuclear physicist whose primary focus is on neutrinoless double-beta decay. Neutrinoless double-beta decay is an extremely rare nuclear process which, if it is ever observed, would show that the neutrino is its own antiparticle, a Majorana particle. A Majorana neutrino would have profound consequences to particle physics and cosmology, among them an explanation of the universe’s matter-antimatter symmetry. Winslow takes part in two projects that search for double-beta decay at CUORE (Cryogenic Underground Observatory for Rare Events) and KamLAND-Zen, and works to develop new, more sensitive double-beta decay detectors. Winslow received her BA in physics and astronomy in 2001 and her PhD in physics in 2008, both from the University of California at Berkeley. After a postdoctoral fellowship at MIT, she was appointed as an assistant professor at the University of California at Los Angeles. Winslow has also been awarded a 2010 L’Oréal for Women in Science Fellowship. Winslow was appointed as an assistant professor at MIT in 2015

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04/09/2018 - 4:15pm
 
 
HEP Seminar: Philip Harris, MIT, CERN

HEP Seminar: Philip Harris, MIT, CERN

Date: 
Wed, 04/11/2018 - 10:00am
Location: 
705 Pupin Hall
**10:00 AM Start Time**

"Hadronically Identified and Generated, after a Generation"

Philip Harris

Massachusetts Institute of Technology & CERN

Standard model production of the Z (or W) boson decaying to light quarks has not been observed in a hadron collider; it was thought to be impossible. We present a new technique to observe these productions and we observe a clear W and Z peak. With the addition of Machine Learning, we apply this approach to resonances decaying to b-quarks and present, for the first time, the Z boson decaying to b-quarks in a single jet and the first measurement of gluon fusion produced Higgs bosons decaying to b-quarks.  Additionally,  we discuss how we can further improve this Higgs boson  measurement by identifying events directly on custom FPGA based electronics as part of the CMS trigger upgrade.  Finally, as a result, we present a new framework to perform Machine Learning algorithms at incredibly high speeds on FPGA processing elements. 

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04/11/2018 - 10:00am
 
CM / AMO Seminar: Rudolf Grimm, Innsbruck

CM / AMO Seminar: Rudolf Grimm, Innsbruck

Date: 
Thu, 04/12/2018 - 12:00pm
Location: 
705 Pupin Hall

"Impurities in an ultracold Fermi sea: Quasiparticles, phase separation and beyond"

Rudolf Grimm

Institute of Experimental Physics, University of Innsbruck, and IQOQI, Austrian Academy of Sciences, Innsbruck, Austria

Impurity physics has emerged as a new branch of research in the field of atomic quantum gases. A central feature is the wide tunability of interactions between the impurities and the surrounding medium. By using magnetically controlled Feshbach resonances, regimes of strong interactions can be reached which reveal intriguing many-body physics. I will present our experiments on fermionic and bosonic potassium impurities immersed in a deeply degenerate Fermi sea of lithium atoms. For fermionic impurities, we study the spectrum of quasiparticle excitations and the regime where the Fermi liquid picture breaks down. For bosonic impurities, we observe small-sized Bose-Einstein condensates and, for repulsive interactions, their phase separation from the Fermi sea. If time permits, I will also introduce a new quantum gas mixture (dysprosium and potassium) with great prospects for future research on fermionic quantum gases.

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04/12/2018 - 12:00pm
 
Grad Student Seminar: Sebastian Will, Columbia

Grad Student Seminar: Sebastian Will, Columbia

Date: 
Fri, 04/13/2018 - 11:00am
Location: 
Pupin Hall Theory Center, 8th floor

Sebastian Will

Department of Physics, Columbia University

Title TBA

Sebastian Will's research group investigates quantum systems of ultracold atoms and molecules. The group cools atoms and molecules to ultracold temperatures just a sliver above absolute zero - reaching the coldest temperatures allowed by nature. Close to absolute zero temperature, the behavior of particles is ultimately determined by the laws of quantum mechanics. Thanks to the precision tools of atomic physics, the group has full control over the quantum state of each particle and the interactions between them. With ultracold gases of atoms and molecules they create new quantum systems and perform quantum simulations of strongly interacting quantum matter. The special focus is the creation and investigation of ultracold molecules that interact via dipolar long-range interactions. Those will allow us to study exotic quantum phases and quantum phase transitions.

https://www.will-lab.com/

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04/13/2018 - 11:00am
 
Special CM Seminar: Michael M. Fogler, UCSD

Special CM Seminar: Michael M. Fogler, UCSD

Date: 
Fri, 04/13/2018 - 11:30am
Location: 
705 Pupin Hall
*Special Day 7 Time*

"Hyperbolic waves in Nature: from nano to Ter(r)a"

Michael M. Fogler

University of California, San Diego

Waves with a hyperbolic dispersion relation are exotic yet surprisingly widespread phenomena that occur in anisotropic media with internal resonances. Such media have been investigated in numerous fields, ranging from condensed matter physics to plasma physics to optics to fluid dynamics and geophysics. Hyperbolic waves can be found in magnetic materials, in both usual and topological insulators, in superconductors, as well as in our oceans, beaches, atmosphere, and space. The characteristic lengths and frequencies of such waves vary from atomic to cosmic. However, they all exhibit certain common attributes, such as strict directionality, diverging density of states, and anomalous reflection. This talk will contain a primer on hyperbolic materials, a recipe for the death ray, and a survey of our nano-optics studies of hyperbolic phonon-polaritons in graphene and boron nitride.

References:
 
1. L. V. Brown et al, “Nanoscale Mapping and Spectroscopy of Nonradiative Hyperbolic Modes in Hexagonal Boron Nitride Nanostructures,” Nano Lett. 18, 1628 (2018).
2. A. J. Giles et al., “Ultralow-loss polaritons in isotopically pure boron nitride,” Nature Mater. 17, 134 (2018).
3. A. J. Giles et al., "Imaging of Anomalous Internal Reflections of Hyperbolic Phonon-Polaritons in Hexagonal Boron Nitride," Nano Lett. 16, 3858 (2016).
4. S. Dai et al., “Subdiffractional focusing and guiding of polaritonic rays in a natural hyperbolic material,” Nature Comms 6, 6963 (2015).
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04/13/2018 - 11:30am
 
 
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Theory Seminar: Blagoje Oblak, ETH

Theory Seminar: Blagoje Oblak, ETH

Date: 
Mon, 04/16/2018 - 2:10pm
Location: 
Pupin Hall Theory Center, 8th Floor

"Berry Phases of Boundary Gravitons"

Blagoje Oblak

Eidgenössische Technische Hochschule (ETH), Zurich

This talk is devoted to Berry phases that appear in unitary representations of asymptotic symmetry groups in general relativity. These phases arise when a coherent state is acted upon by symmetry transformations that trace a closed path in the group manifold, and they can be evaluated exactly even when the group is infinite-dimensional. We apply these ideas to the Virasoro and BMS groups; seeing their representations as particles dressed with boundary gravitons, the associated Berry phases generalize Thomas precession and provide, in principle, observable signatures of asymptotic symmetries.

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04/16/2018 - 2:10pm
 
Colloquium: Kip Thorne, Caltech

Colloquium: Kip Thorne, Caltech

Date: 
Mon, 04/16/2018 - 4:15pm
Location: 
428 Pupin Hall
Please join us Monday, April 16, 2018, as Kip Thorne of Caltech gives his colloquium.
 
Kip is the recipient of the The Nobel Prize in Physics 2017 and also the scientific consultant and executive producer of the movie Interstellar.
 
Born in Logan Utah in 1940, Kip Thorne received his B.S. degree from Caltech in 1962 and his Ph.D. from Princeton University in 1965. He returned to Caltech as an Associate professor in 1967 and became Professor of Theoretical Physics in 1970, The William R. Kenan, Jr., Professor in 1981, The Feynman Professor of Theoretical Physics in 1991, and The Feynman Professor of Theoretical Physics, Emeritus, in 2009. Thorne's research has focused on Einstein's general theory of relativity and on astrophysics, with emphasis on relativistic stars, black holes and especially gravitational waves. He was cofounder (with R. Weiss and R.W.P. Drever) of the LIGO (Laser Interferometer Gravitational Wave Observatory) Project, with which he is still associated.
 
Thorne was elected to the American Academy of Arts and Sciences in 1972, the National Academy of Sciences in 1973, and the Russian Academy of Sciences and the American Philosophical Society in 1999. He has been awarded the Lilienfeld Prize of the American Physical Society, the Karl Schwarzschild Medal of the German Astronomical Society, the Albert Einstein Medal of the Albert Einstein Society in Berne, Switzerland, the UNESCO Niels Bohr Gold Medal from UNESCO, and the Common Wealth Award for Science, and was named California Scientist of the Year in 2004. For his book for nonscientists, Black Holes and Time Warps: Einstein's Outrageous Legacy (Norton Publishers 1994), Thorne was awarded the American Institute of Physics Science Writing Award, the Phi Beta Kappa Science Writing Award, and the (Russian) Priroda Readers' Choice Award. In 1973 Thorne coauthored the textbook Gravitation, from which most of the present generation of scientists have learned general relativity theory. Fifty-two physicists have received the PhD at Caltech under Thorne's personal mentorship.
 
In 2009 Thorne stepped down from his Feynman Professorship at Caltech in order to ramp up a new career in writing, movies and continued scientific research. His current writing focus is a textbook on classical physics coauthored with Roger Blandford; his current movie focus is Christopher Nolan's Interstellar, on which he is an executive producer, and with Lynda Obst he coauthored the Treatment from which the movie sprang; his current research is on the nonlinear dynamics of curved spacetime. 
 
 
Colleagues outside of Columbia please RSVP through Eventbrite link here
 
 
* A reception of wine & cheese will immediately follow at the Pupin Hall Theory Center on the 8th floor*
 
 
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04/16/2018 - 4:15pm
 
 
Theory Seminar: Mark Raugas, PNNL

Theory Seminar: Mark Raugas, PNNL

Date: 
Wed, 04/18/2018 - 2:00pm
Location: 
Pupin Hall Theory Center, 8th floor

"Using Deep Learning to help construct a sheaf over the arXiv"

Mark Raugas

Pacific Northwest National Laboratory

Significant progress has been made in recent years in Natural Language Processing (NLP), Computer Vision (CV), Signal Processing and Reinforcement Learning (RL) tasks using Deep Learning.  At the same time, the volume of scientific publishing has been ever increasing and it is becoming more and more difficult for researchers to keep pace with preprints in a variety of fields in a meaningful way.  In this talk, I will highlight some efforts at Pacific Northwest National Laboratory (PNNL) in applying Deep Learning to aid scientific discovery in chemistry, computer science, and physics.  I will then describe an emerging effort at PNNL to enhance topic modeling of scientific publications to help detect interesting scientific advances based on an author’s current interests or work.  Methods of computer semantic understanding of technical publications would be developed using applications of linear algebra, sheaf theory, and deep learning.

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04/18/2018 - 2:00pm
 
 
Grad Student Seminar: Elena Aprile, Columbia

Grad Student Seminar: Elena Aprile, Columbia

Date: 
Fri, 04/20/2018 - 11:00am
Location: 
Pupin Hall Theory Center, 8th floor

"Dark Matter"

Elena Aprile

Department of Astrophysics, Columbia University

The Aprile Group uses liquid xenon (LXe) to detect and image radiation from a variety of physics phenomena in astrophysics and particle physics. Prof. Aprile has been involved for many years in the development of cryogenic noble liquid detectors and has carried out, with her students, postdocs and colleagues from around the world, many measurements of the properties of liquid argon (LAr), liquid krypton (LKr), and LXe (see publications). Currently the group is focused on the XENON Dark Matter Experiment, while continuing R&D to improve the performance of noble liquid time projection chambers, with a special emphasis on combining the ionization and the VUV scintillation from these materials for precise energy measurement and imaging.

http://xenon.astro.columbia.edu/group.html

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04/20/2018 - 11:00am
 
 
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Theory seminar: Edgar Shaghoulian, Cornell

Theory seminar: Edgar Shaghoulian, Cornell

Date: 
Mon, 04/23/2018 - 2:10pm
Location: 
Pupin Hall Theory Center, 8th Floor

"Higher form symmetries and the emergence of gravity"

Edgar Shaghoulian

Cornell Uinversity

I will discuss how endowing a field theory with a particular pattern of higher-form symmetry breaking captures many features of an emergent, local gravitational description. This will also provide a new viewpoint on why holographic field theories are formulated as gauge theories and why nonlocal objects like strings and membranes need to exist in the bulk for there to be a local gravitational limit.

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04/23/2018 - 2:10pm
 
Colloquium: Matt Reagor, Rigetti Quantum Computing

Colloquium: Matt Reagor, Rigetti Quantum Computing

Date: 
Mon, 04/23/2018 - 4:15pm
Location: 
428 Pupin Hall

"Parametric Entangling Gates in a Superconducting Quantum Processor And Applications”

Matt Reagor

Rigetti Quantum Computing

A central challenge in building a scalable quantum computer is the execution of high-fidelity entangling gates within an architecture containing many resonant elements. As elements are added, or as the multiplicity of couplings between elements is increased, the frequency space of the design becomes crowded and device performance suffers. By applying flux modulation to tunable transmons, one can drive the resonant exchange of photons directly between energy levels of a statically coupled multi-transmon system. This obviates the need for mediating qubits or resonator modes and allows the full utilization of all qubits in a scalable architecture. The resonance condition is selective in both the frequency and amplitude of modulation and thus alleviates frequency crowding. We discuss using these techniques to scale superconducting qubit processors to lattices containing 19 qubits and the results of initial hybrid quantum algorithms run on such processors.

About the speaker

Matt Reagor is an experimental physicist at Rigetti Quantum Computing. His team is advancing the capability of superconducting quantum processors in close collaboration with a diverse set of engineers. Prior to Rigetti, Matt earned a PhD in the Schoelkopf Lab at Yale on a millisecond quantum memory for superconducting qubits.

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04/23/2018 - 4:15pm
 
AMO Seminar: Ivan Kozyryev, Harvard

AMO Seminar: Ivan Kozyryev, Harvard

Date: 
Tue, 04/24/2018 - 11:00am
Location: 
705 Pupin Hall

**Special Day & Time**

"Direct laser cooling of polyatomic molecules"

Ivan Kozyryev

Harvard University

Qualitatively new vibrational and rotational motions present in complex molecules with three and more atoms offer unique opportunities for advancing various research areas within physics, chemistry and quantum technology.  We have identified a large class of polyatomic molecules, alkaline earth monoalkoxides (MOR), with diverse constituents and geometries that have strong optical transitions and diagonal Franck-Condon factors, enabling photon cycling.  I will describe our results on direct Doppler and Sisyphus laser cooling of the linear triatomic radical strontium monohydroxide (SrOH).  Additionally, using stimulated bichromatic force, we achieved a factor of 4 force enhancement compared to radiation pressure, paving the way for rapid coherent deceleration of molecular beams.  Finally, I will outline the prospects of using laser-cooled polyatomic molecules to probe physics beyond the Standard Model via permanent electric dipole moment search or spectroscopic effects arising from interactions with ultralight bosonic dark matter.

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04/24/2018 - 11:00am
 
HEP Seminar: Zara Bagdasarian, Forschungszentrum Jülich

HEP Seminar: Zara Bagdasarian, Forschungszentrum Jülich

Date: 
Wed, 04/25/2018 - 1:00pm
Location: 
705 Pupin Hall

"Everything you need to know about the Borexino new results"

Zara Bagdasarian

Forschungszentrum Jülich

Borexino is located at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy with the primary goal of detecting solar neutrinos, particularly those below 2 MeV, with unprecedentedly high sensitivity. The ultra-low radioactive background, Borexino’s technical distinctive feature, is the basis of the outstanding achievements obtained so far. Since the start of operations in 2007, Borexino produced the first time measurements of 7Be, pp, and pep solar neutrinos, and set the best available upper limit on the flux of solar neutrinos produced in the CNO cycle (carbon, nitrogen, oxygen). The Borexino collaboration has recently completed the new measurements of the pp, pep, 7Be, hep and 8B neutrinos. These neutrinos are the products of the pp-chain of nuclear fusion reactions generating more than 99% of the Sun’s energy.
 

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04/25/2018 - 1:00pm
 
 
HEP Seminar: Christian Mariaud, LLR, Ecole Polytechnique

HEP Seminar: Christian Mariaud, LLR, Ecole Polytechnique

Date: 
Fri, 04/27/2018 - 1:15pm
Location: 
705 Pupin Hall

**Special Astro-particle Day & Time**

 

"Studies of binary systems at TeV Energies with H.E.S.S."

Christian Mariaud

LLR, Ecole Polytechnique

VHE-emitting binary systems are rare in gamma astronomy, and only seven binary systems are currently known.These objects have common characteristics, with a very massive star of type O or Be and a compact object. The nature of the compact object is often unknown and could be a neutron star or black hole. However, in spite of their relatively small number, several mechanisms of acceleration and gamma photon production are currently under study (microquasar, pulsar with a massive star of type Be, and compact object with a massive star of type O). VHE variability is often related to the revolution and also a modulation of the flux of photons depending on the period of the compact object. The geographical position of the H.E.S.S. telescopes, located in Namibia, enables the study of these binary systems: LS 5039, PSR B1259, HESS J0632+057, 1FGL J1018.6-5856 and LMC P3. In our presentation, we will focus mainly on two binary systems, LS 5039 and PSR B1259. Indeed, these two systems have different characteristics and have been observed for a long time by the network of H.E.S.S. and Fermi-LAT telescopes. Finally, we will consider the possibility of improving the data by studying the impact that the transparency of the atmosphere and the effect of the Earth magnetic field can have on the Cerenkov images.
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04/27/2018 - 1:15pm
 
 
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Theory seminar: Mariana Carrillo-Gonzalez, UPenn

Theory seminar: Mariana Carrillo-Gonzalez, UPenn

Date: 
Mon, 04/30/2018 - 2:10pm
Location: 
Pupin Hall Theory Center, 8th Floor

"The classical double copy in maximally symmetric spacetimes"

Mariana Carrillo-Gonzalez

University of Pennsylvania

In this talk, I will briefly explain the scattering amplitudes double copy. The double copy is a relation between Yang-Mills and gravitational theories but recently it has been shown that it applies more broadly to other theories. By exploring the question on how general this double copy relationship is, classical double copy realizations have been recently explored in flat space. One of this examples constructs exact solutions by using a Kerr-Schild metric. I will focus on the generalization to maximally symmetric curved spacetimes in the context of this Kerr-Schild double copy and show how the Yang-Mills and bi-adjoint scalar equations of motion are encoded in Einstein's equations.

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04/30/2018 - 2:10pm
 
Colloquium: Joe Orenstein, UC Berkeley

Colloquium: Joe Orenstein, UC Berkeley

Date: 
Mon, 04/30/2018 - 4:15pm
Location: 
428 Pupin

"California New Age Physics: Sunshine, Crystals, and Quantum Physics of Bands"

Joe Orenstein

Physics Department, UC Berkeley and Materials Research Division, LBNL

Nonlinear optical properties of materials are important as tools in basic research and optical technology. Recently there has been a tremendous upsurge of interest in optical nonlinear effects, especially in crystals with curved bandstructure geometry. Such materials are candidates for applications based on the conversion of light to dc current. In this talk I describe our discovery that a family of Weyl semimetals has by far the largest second-order susceptibility of any previously known crystal. In puzzling over this result, we uncovered a surprising theorem relating the strength of optical nonlinearity to a quantum invariant property of the bandstructure that unites nonlinear optics with the celebrated “modern theory of polarization.” This quantum invariant provides a new strategy for algorithmic computational searches for nonlinear materials with optimal response functions.

About the speaker

Joseph W. Orenstein earned his Ph.D. in Solid State Physics from the Massachusetts Institute of Technology in 1980. He received an IBM Postdoctoral Fellowship 1978-79, and was a Member of the Technical Staff at the AT&T Bell Laboratories from 1981 to 1989. In 1989, he was made a Distinguished Member of the Technical Staff. He joined the Physics Dept. at UC Berkeley in 1990. He is a Fellow of the American Physical Society.

Joe Orenstein's research group we use light (or electromagnetic radiation to we physicists) to probe condensed matter systems. They measure quantities like transmission and reflection coefficients, and nonlinear optical properties as well. For different experiments, the gourp uses light waves whose wavelength varies from the millimeter range to less than 0.5 micron. Currently, they are studying high-Tc superconductors organic molecular crystals.

More details on Joe Orenstein's research can be found here.

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04/30/2018 - 4:15pm
 
 
 
 
 
 
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