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 Colloquia & Seminars
 Postdoctoral Research Seminars1) Speaker: Michael Foss-Feig Title:Entanglement in long-range interacting systems. Abstract: It is well known that infinite-range interactions can facilitate the generation of massively entangled states with applications in quantum information and quantum metrology. From a theoretical standpoint, such infinite-range interactions are convenient to assume because they greatly simplify the description of dynamics, but in physical systems "infinite-range" is clearly an approximation. In this talk, I will describe what happens to a number of experimentally relevant systems when interactions are long-ranged but not infinite-ranged. 2) Speaker: Zhexuan Gong Title: Propagation of information in long range interacting quantum systems Abstract: Propagation of information in short-range interacting systems is restricted to within a linear "light cone", as proven by the well-known Lieb-Robinson bound, thus ensuring a well defined notion of locality. Whether long-ranged interactions can lead to a different shape of this light cone, and the breakdown of the associated notion of locality, is an important but largely unexplored question. I will describe recent trapped-ion experiments which have observed nonlocal propagation of correlations in certain long-ranged interacting spin models, and will discuss our theoretical efforts to understand how, as the interaction range shrinks, locality is recovered. 3) Speaker: Fred Jendrzejewski Title: From compressed Bose-Einstein condensates to spirals-New Experiments with superfluid atom circuits Abstract: Bose-Einstein condensates in ring geometries are essential ingredients to the ongoing effort at JQI of building increasingly complex superfluid circuits. Such circuits have previously allowed for the observation of persistent currents and hysteresis. Here we report on two new experiments that increase our abilities further. First, we report the direct observation of resistive flow through a weak link in a weakly interacting atomic Bose- Einstein condensate. We use two weak links to separate our ring-shaped superfluid circuit into two distinct regions, a source and a drain. At a critical value of the weak link velocity, we observe a transition from superfluid flow to superfluid plus resistive flow. Second, we demonstrate a new technique to directly observe the current-phase relationship through such weak links. By interfering our ring with a phase reference (formed as a disc), we demonstrate that we can measure the phase of the BEC around the ring and the average current.When: Mon, March 10, 2014 - 11:00amWhere: CSS 2400 EPT Joint Seminar w/ Johns HopkinsJoint Particle theory-experiment Maryland-Hopkins Seminar Seminar will be preceded by lunch at 12.30 pm. The talk is from 2:00 to 3:00 pm. Title: Probing the 1000 TeV Energy Scale: Searches for Muon and Electron Number Violation at Unprecedented Sensitivity Speaker: William Molzon, UC Irvine Abstract: Violation of electron, muon, and tau lepton numbers in the charged sector [CLFV] is an unambiguous signature of new physical processes; the Standard Model, modified to include neutrino mass and mixing, predicts rates for CLFV processes at an immeasurably low rate. In contrast, many models for new physics allow CLFV, and even current limits severely constrain various models’ parameter space. Current and planned advances in muon beam intensities and e+e- collider luminosities, coupled with new detectors with improved rate capabilities and resolutions, provide prospects for much improved experimental sensitivity. I will briefly review the current experimental status and models that predict CLFV and then discuss results from ongoing experiments and prospects for new experiments that will improve on earlier results, concentrating on muon induced processes: μ+→e+γ, μ+→e+e+e-, and μ-N→e-N.When: Mon, March 10, 2014 - 12:30pmWhere: Bloomberg Hall, John's Hopkins University Nuclear Physics SeminarTitle: Neutron in a strong magnetic field and effects from finite volume Speaker: Brian Tiburzi, CCNY Abstract: Computation of magnetic properties of the neutron using lattice QCD in uniform magnetic fields is subject to various systematic effects. I will give an overview of a quantitative attempt to understand these systematics focusing on non-perturbative magnetic field strengths in both infinite and finite volume. While there is rich physics at finite volume (gauge holonomies and the Aharonov-Bohm effect), simple results are nonetheless obtained.When: Mon, March 10, 2014 - 1:30pmWhere: PSC 3150 CMTC SeminarSpeaker: David Abergel Institution: Nordic Institute for Theoretical Physics Title: Excitonic Condensation in Double Layer Graphene: the Role of Disorder Abstract: The existence of an excitonic condensate in double layer graphene has been predicted theoretically, but has not been observed in experiment. We discuss the conditions under which this condensate has a critical temperature high enough to allow detection. Crucially, disorder arising from charged impurities and corrugation in the lattice structure affects the formation of the condensate via the induced charge inhomogeneity. We employ mean-field BCS theory to describe the condensate formation, and a numerical Thomas-Fermi-Dirac theory to describe the disorder. Combining these calculations gives realistic estimates of the likelihood of observing the condensate in different experimental situations. Host: Ed Barnes http://www.physics.umd.edu/cmtc/seminars.htmlWhen: Mon, March 10, 2014 - 2:00pmWhere: 2205 Physics Building Biophysics SeminarSpeaker Name: Irene Chen Speaker Institution : UC Santa Barbara Title: RNA evolution in early life. Abstract: The origin of life is believed to have progressed through an RNA World, in which RNA acted as both genetic material and functional molecules. I will describe our work toward mapping complete evolutionary fitness landscapes and lessons on the role of natural selection and historical accidents in early evolution. I will also describe our work on the emergence, survival, and spread of evolutionary innovations during the origin of life. Notes: *Refreshments at 3:45pm For further information contact: Dr. Wolfgang Losert, CoordinatorWhen: Mon, March 10, 2014 - 4:00pmWhere: 0112 Chemistry Bldg. (Marker Room) Space and Cosmic Ray Physics - No seminar this weekWhen: Mon, March 10, 2014 - 4:30pmWhere: CMTC SeminarSpeaker: Meng Cheng Institution: Microsoft Station Q Title: Unconventional edge phases of Abelian quantum Hall states Abstract: Integer and fractional quantum Hall states exhibit gapless edge excitations which allow probing of many bulk topological properties through transport experiments. We find that the same bulk two-dimensional topological phase can have multiple distinct, fully-chiral edge phases, with experimentally testable signatures. We show that this can occur in the integer quantum Hall states at \nu=8 and \nu=12, as well as in fractional quantum Hall states, the simplest examples of which being \nu=8/7, 12/11, 8/15, 16/15. We also demonstrate that fermionic systems can have chiral edge phases with only bosonic low-energy excitations. We explain these results using the theory of integral quadratic forms. Host: Sriram Ganeshan http://www.physics.umd.edu/cmtc/seminars.htmlWhen: Tue, March 11, 2014 - 11:00amWhere: 2205 Physics Building Informal Statistical Physics SeminarSpeaker Name: Professor Pierre Gaspard Speaker Institution : University Libre de Bruxelles Title : Thermodynamics Meets Information in Copolymerization Processes Notes: As in the past, each seminar will be preceded by an Informal Cafeteria Lunch to which all are welcome, departing from room 1108 about five minutes after 12:00 (Noon). For further information contact: Professor Christopher Jarzynski, This e-mail address is being protected from spambots. You need JavaScript enabled to view it (301)405-4439 Professor John Weeks, This e-mail address is being protected from spambots. You need JavaScript enabled to view it , (301)405-4802 Professor Michelle Girvan, This e-mail address is being protected from spambots. You need JavaScript enabled to view it (301)405-1610When: Tue, March 11, 2014 - 1:15pmWhere: Room 1116 IPST Building, Bldg 85 Physics ColloquiumSpeaker Name: Bonnie Fleming Speaker Institution: Yale University Title: v Measurements, New Physics: Short and Long Baseline ve appearance Abstract: 2012 was a banner year for particle physics with both the Higgs discovery and the measurement of θ13, the last of the unknown mixing angles in the PMNS matrix. With a large value of θ13, the neutrino community is poised to measure long baseline neutrino oscillations and look for CP violation in the neutrino sector. At short baselines, puzzles remain with hints from a number of experiments worldwide suggesting new physics. Long and short baseline accelerator neutrino experiments alike are developing precision Liquid Argon Time Projection Chamber detectors to do these ve appearance searches. The US neutrino program, envisioned and in progress, to develop this technology and address these questions, will be described.When: Tue, March 11, 2014 - 4:00pmWhere: PHYS 1412 CMTC SeminarSpeaker: Maissam Barkeshli Institution: Microsoft Station Q Title: Abstract: Host: Jay Deep Sau http://www.physics.umd.edu/cmtc/seminars.htmlWhen: Wed, March 12, 2014 - 11:00amWhere: 2205 Physics Building JQI Special SeminarSpeaker: Sidney Cahn Institution: Yale University Title: The Search for Nuclear Anapole Moments in Diatomic Molecules Abstract: The Search for Nuclear Anapole Moments in Diatomic Molecules: Nuclear spin-dependent parity nonconservation (NSD-PNC) eﬀects arise from exchange of the Z0 boson (parameterized by the electroweak coupling constants C2{P,N } ) between electrons and the nucleus, and from the interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The latter scales with the nucleon number A of the nucleus as A3/2, while the Z0 coupling is independent of A; the former will be the dominant source of NSD-PNC in nuclei with A ≥ 20. NSD-PNC eﬀects can be dramatically amplified in diatomic molecules by bringing two levels of opposite parity close to degeneracy in a strong magnetic ﬁeld. This opens the prospect for measurements across a broad range of nuclei. As a precursor to the measurement of the nuclear anapole moment of 137Ba, we have experimentally observed and characterized opposite-parity level crossings in 138BaF. These are found to be in excellent agreement with parameter-free predictions and indicate that the sensitivity necessary for NSD-PNC measurements should be within reach. They have also provided a two-level system in which a form of molecular interferometer obtains, whose fringes exhibit Airy function-like behavior. Host: Luis A. OrozcoWhen: Wed, March 12, 2014 - 12:00pmWhere: CSS 2115 Refreshments for CNAM ColloquiumWhen: Thu, March 13, 2014 - 1:30pmWhere: Phys room 1305F; the "new" Toll Room CNAM ColloquiumSpeaker Name: Ivar Martin Speaker Institution: Los Alamos National Lab Title: SPONTANEOUS QUANTUM HALL EFFECT AND FRACTIONALIZATION IN ITINERANT CHIRAL MAGNETS Abstract: When electrons move in a magnetic material, their transport can be profoundly affected by scattering off magnetic ions. Converse is also true: Itinerant electrons themselves can define the magnetic state into which the system orders. Even though typically these magnetic states are simple e.g. ferromagnetic or antiferromagnetic sometimes, complex chiral magnetism can appear. Non-coplanar itinerant magnets are expected to exhibit highly unusual transport phenomena that stem from a quantum coherent effect of non-coplanar magnetic ordering on electrons, which is similar to the Aharonov-Bohm effect. It can lead to the spontaneous quantum Hall effect and ground-state electrical and spin currents. The equivalent strength of the orbital magnetic field can exceed 10^4 Tesla. The stable topological excitations (magnetic vortices) in these states can carry fractional electronic charge and spin and realize anyonic exchange statistics. In this talk I will present several examples of two- and three-dimensional itinerant models of magnetism that exhibit complex non-coplanar ordering even in the absence of spin orbit interaction; I will describe possible material realizations. Host: Vladimir ManucharyanWhen: Thu, March 13, 2014 - 2:00pmWhere: PHYS Room 1201 MCFP ColloquiumTitle: Compositeness and Physics Beyond the Standard Model Speaker: George Fleming, Yale Abstract: The great discovery of a Higgs-like scalar boson around 126 GeV at the Large Hadron Collider (LHC), along with an absence of evidence for TeV-scale supersymmetry (SUSY), has left the theoretical community struggling to find an answer to the hierarchy problem of the Standard Model Higgs boson. A composite Higgs boson can naturally solve the hierarchy problem. It would be a great advance in theoretical physics to understand whether composite Higgs bosons can arise as pseudo-Nambu-Goldstone bosons (pNGB’s) in certain confining gauge theories or as pseudo-dilatons in nearly conformal gauge theories. Without TeV-scale SUSY and direct detection of dark matter at XENON100 and LUX, the WIMP miracle'' may now seem a coincidence, but I will point out that there are still composite candidates that can fit the paradigm.When: Thu, March 13, 2014 - 4:00pmWhere: PSC 3150 Spring Break - No ColloquiaWhen: Tue, March 18, 2014 - 4:00pmWhere: Spring Break - No SeminarsWhen: Sun, March 16, 2014 - 8:00pmWhere: JQI SeminarSpeaker: John Bollinger, NIST Boulder Title: Quantum control and simulation with 2-dimensional arrays of trapped ions Abstract: Trapped ions, when cooled to sufficiently low temperatures form crystalline arrays. I will describe our efforts to extend the quantum control techniques developed with linear chains of ions in rf traps to two-dimensional triangular arrays of hundreds of ions formed in a Penning trap. Penning traps use a uniform magnetic field and static electric fields to confine charged particles. Our qubit is the 124 GHz electron spin-flip transition in the ground state of Be+ in the 4.5 T magnetic field of the Penning trap. We control the spins with an effective transverse magnetic field generated with 124 GHz microwaves. Spin-dependent optical dipole forces are used to engineer long range Ising interactions between the ion qubits, and to characterize the motional degrees of freedom of the trapped ions. This system has the potential for simulating quantum non-equilibrium phenomena with an intractable number of spins. Host: Luis OrozcoWhen: Mon, March 24, 2014 - 11:00amWhere: CSS 2400 EPT SeminarTitle: TBA Speaker: Anson Hook, Princeton Abstract: TBAWhen: Mon, March 24, 2014 - 3:00pmWhere: PSC 3150 Biophysics SeminarSpeaker Name: Karissa Sanbonmatsu Speaker Institution : Los Alamos National Laboratory Title: TBA Abstract: TBAWhen: Mon, March 24, 2014 - 4:00pmWhere: 0112 Chemistry Bldg. Space and Cosmic Ray Physics SeminarSpeaker Name: Keith Strong and Julia Saba Speaker Institution : NASA Goddard Space Flight Center and Univ. of Maryland Astronomy Dept. Title : The Solar Cycle Conundrum Abstract : We have known for 170 years that sunspots come and go on a roughly 11-year timescale. Despite many efforts to develop empirical or physical models of the solar cycle, we have failed to find a method of predicting the timing or amplitude of an upcoming solar cycle with any degree of confidence. While this was once considered an interesting intellectual exercise to test how well we understood the inner workings of the Sun, it now has become an important economic issue as our dependence on space technology increases. The vulnerability of over T in space assets to space weather effects increases with the solar activity levels that are driven by the solar cycle. The Sun is a magnetic variable star so we will look at the basic characteristics of the solar dynamo that have to be reproduced by any viable solar cycle model. Then we will briefly discuss some of the techniques used to predict solar activity and see how well they have done so far in predicting the current solar cycle. Using extended observations of the Sun's magnetic field from SOHO and various ground-based observatories in conjunction with coronal imaging has led us to find some new patterns in solar activity that have shown promise in predicting certain aspects of the solar cycle. Notes: Coffee, Tea & Cookies 4:15-4:30 PMWhen: Mon, March 24, 2014 - 4:30pmWhere: CSS 2400