Dr. Marko Gacesa,
BAER Institute / NASA Ames Research Center

Photoassociation of ultracold molecular ions and controlling atom-ion charge exchange using magnetic Feshbach resonances

Feshbach resonances offer a way to control the strength and sign of particle-particle interactions in ultracold atomic and molecular gases by tuning external magnetic or electric fields. This discovery led to a number of experimental applications in ultracold AMO physics, in particular in preparation and production of dense samples of ultracold molecules. Because of their importance, Feshbach resonances have been measured and characterized in numerous of neutral diatomic mixtures. A natural generalization of studies of neutral ultracold gases includes atom-ion mixtures, which remain much less investigated than neutral systems. Atom-ion interactions are, generally, more difficult to investigate due to their long-range nature and presence of the charge. Nevertheless, the same properties also offer a window to investigate different physical regimes than the ones accessible by the neutral systems.

In this talk, I will present recent results, obtained in collaboration with the group of Prof. Robin Cote, related to using external magnetic and electric fields in controlling charge-exchange in atom-ion collisions. Specifically, I will present our theoretical investigation of magnetic Feshbach resonances and their application to controlled charge transfer in \({}^{9,10}\)Be + \({}^{9,10}\)Be+, and \({}^{40}\)Ca+\({}^{43}\)Ca+ both of which are good model systems for heavier and more complex elements. I will also present the results of first theoretical study of photoassociative formation of cold molecular ions, where we estimated the production rates of NaCa+ molecular ions from trapped cold Na+ ions and Ca atoms. This study is based on experiments conducted in the group of Prof. W. Smith at UConn.

Dr. Thomas Allison,
Stony Brook University


Ultrafast extreme ultraviolet photoemission without space charge


Time- and Angle-resolved photoelectron spectroscopy from surfaces can be used to record the dynamics of electrons and holes in condensed matter on ultrafast time scales. However, ultrafast photoemission experiments using extreme-ultraviolet (XUV) light have previously been limited by either space-charge effects, low photon flux, or limited tuning range. In this article, we describe space-charge-free XUV photoelectron spectroscopy experiments with up to 5 nA of average sample current using a tunable cavity-enhanced high-harmonic source operating at 88 MHz repetition rate. The source delivers \(> 10^{11}\) photons/s in isolated harmonics to the sample over a broad photon energy range from 18 to 37 eV with a spot size of \(58 \times 100 \mu m^2\). From photoelectron spectroscopy data, we place conservative upper limits on the XUV pulse duration and photon energy bandwidth of 93 fs and 65 meV, respectively. The high photocurrent, lack of space charge distortions of the photoelectron spectra, and excellent isolation of individual harmonic orders allow us to observe laser-induced changes to the photoelectron spectrum at the \(10^{-4}\) level in minutes of integration time, enabling time-resolved XUV photoemission experiments in a qualitatively new regime. I will discuss demonstration experiments on Au (111) and progress towards electron dynamics in molecular films.

Dr. Thomas Allison
Stony Brook University


Cavity-enhanced ultrafast spectroscopy: ultrafast meets ultrasensitive


Ultrafast optical spectroscopy methods, such as transient absorption spectroscopy and 2D spectroscopy, are widely used across many disciplines. However, these techniques are typically restricted to optically thick samples, such as solids and liquid solutions. Using a frequency comb laser and optical cavities, we present a technique for performing ultrafast optical spectroscopy with high sensitivity, enabling work in dilute gas-phase molecular beams. Resonantly enhancing the probe pulses, we demonstrate transient absorption measurements with a detection limit of \(\Delta OD = 2 \times 10^{−10}\) (\(1 \times 10^{-9} / \sqrt{Hz}\)). Resonantly enhancing the pump pulses allows us to produce a high excitation fraction at a high repetition rate, so that signals can be recorded from samples with optical densities as low as \(OD ≈ 10^{−8}\), or column densities \( < 10^{10}\) molecules∕cm\(^2\). In this talk, I will discuss initial demonstration experiments, methods for cavity-enhancing multidimensional spectroscopy signals using multiple frequency combs, and progress towards widely tunable cavity-enhanced ultrafast spectrometers operating from the ultraviolet to the infrared.

Jonathan Kwolek,
Department of Physics,
University of Connecticut

Studying Charge Exchange in a Hybrid Ion-neutral Trap


Interactions between neutral and ionized atoms are medium-range, and the spiraling nature of these collisions can lead to long interaction times and large cross sections. The field of ion-neutral interactions is bolstered by methods from atomic physics, which allow us to accurately control and determine the quantum-states of the reactants. Atomic physics opens the door to studying these interactions over a large range of energies, in order to observe interesting effects from the ultracold to hot temperature regimes.

The hybrid-trap enables the concentric trapping of a sample of cold atoms and ions. The dissertation discusses our exploration into the controlled reactions in the Na+Ca^+ system, including measurements of sympathetic cooling and a charge-exchange rate which changes as a function of energy and atomic state. The quantum-state distributions of Na in our magneto-optical trap is also explored, as well as its agreement and subsequent deviation based on a predictive model. The measurements of reaction rates indicate a reaction-energy threshold in two different reaction channels, which can be corroborated by theoretical investigation.

Dr. Daniel Angles-Alcazar,
Center for Computational Astrophysics, Flatiron Institute

The dual role of stellar feedback regulating galaxy evolution and the growth of supermassive black holes


Feedback from massive stars, including supernovae, stellar winds, and radiation, is believed to play a central role in galaxy evolution. In this talk, I will present recent progress in understanding the implications of stellar feedback using cosmological hydrodynamic simulations from the Feedback In Realistic Environments (FIRE) project. In these simulations, stellar feedback regulates star formation locally in galaxies while driving large-scale winds that connect galaxies with their surrounding circumgalactic medium. I will discuss the efficiency of winds evacuating gas from galaxies, the importance of wind re-accretion to galaxy mass assembly, and the surprising contribution of intergalactic transfer of material between galaxies via winds. Zooming into galactic nuclei, I will show that stellar feedback regulates the early growth of the central black hole in low mass galaxies by continuously evacuating the nuclear gas reservoir, which has important implications for the co-evolution of supermassive black holes and galaxies and the frequency and mass scale of massive black hole mergers.

Dr. Nora Kling
Department of Physics,
University of Connecticut

Ultrafast Nuclear Motion: Resolving Hydrogen Migration(s) in Time

Intramolecular hydrogen migration is a natural process that plays a crucial role in many biological, chemical, and physical phenomena, and is the object of current research efforts in fuel cells, proteomics, and combustion chemistry. Using ultrafast, intense lasers and sophisticated pump-probe ion imaging techniques, we can explore the rich dynamics of hydrogen migration reactions, including what timescale they occur on. In my talk, I will present two studies. The first study is on acetylene, a small hydrocarbon, where a hydrogen can migrate across the carbon atoms to form its vinylidene isomer [1,2]. The second study is on ethanol, a complex molecule where both single and double hydrogen migrations occur, and the timescale for each is individually determined [3]. These experimental results, in combination with state-of-the art quantum chemical trajectory calculations, give us new insight into the complex nuclear motions in complex polyatomic molecules.



[1] C. Burger et al. Faraday Discussions 194, 495 (2016).

[2] M. Kübel et al. Phys. Rev. Lett. 116, 193001 (2016).

[3] N. G. Kling et al. submitted for publication

Dr. David Murphy, MIT

Matrix Elements for Neutrinoless Double Beta Decay from Lattice QCD

While neutrino oscillation experiments have demonstrated that neutrinos have small, nonzero masses, much remains unknown about their properties and decay modes. One potential decay mode --- neutrinoless double beta decay (\(0 \nu \beta \beta\)) --- is a particularly interesting target of experimental searches, since its observation would imply both the violation of lepton number conservation in nature as well as the existence of at least one Majorana neutrino, in addition to giving further constraints on the neutrino masses and mixing angles. Relating experimental constraints on \(0 \nu \beta \beta\) decay rates to the neutrino masses, however, requires theoretical input in the form of non-perturbative nuclear matrix elements which remain difficult to calculate reliably. In this talk we will discuss progress towards first-principles calculations of relevant nuclear matrix elements using lattice QCD and effective field theory techniques, assuming neutrinoless double beta decay mediated by a light Majorana neutrino.

Professor Nadia Fomin, University of Tennessee

Life and Death of the Free Neutron

Modern neutron sources provide extraordinary opportunities to study a wide variety of physics topics, including the physical system of the neutron itself. One of the processes under the microscope, neutron beta decay, is an archetype for all semi-leptonic charged-current weak processes. Precise measurements of the correlation parameters in neutron beta decay as well as the neutron lifetime itself are required for tests of the Standard Model and for searches of new physics. The state of the field will be presented and a program of current and future experiments and potential impacts explored.

Dr. Turgut Yilmaz, Department of Physics, University of Connecticut

Topological insulators and their interaction with magnetic impurities and superconductors

Topological properties of materials have recently attracted much attention in the condensed matter physics community due, in part to their possible applications in quantum electronic devices. In particular, topological insulators (TIs) that possess gapless surface states that are topologically protected and can lead to dissipationless quantum electronics. TI's surface state exhibit relativistic momentum dispersion with the Dirac point (DP) located at the time reversal invariant momenta point while the bulk bands are inverted and gapped [1]. Currently, two majority experimental efforts have concentrated on inducing the magnetic and superconducting properties in TI, which would lead to the experimental realizations of quantum anomalous Hall effect (QAHE) and Majorana fermions, respectively [2-3].

Magnetism can be induced in TIs by incorporating impurities into the bulk or on the surface of TIs. If there is a net out-of-plane magnetic moment, an energy gap opens at the DP due to broken time reversal symmetry, which would give rise to QAHE. On the other hand, the superconductivity in can be induced in TI through the proximity effect by growing TIs on the surface of a superconductor. Both, the gapped DP and the superconductivity can be probed by angle-resolve photoemission spectroscopy (ARPES). In this talk, I will present our photoemission studies on the search of broken time reversal symmetry in magnetic TIs and proximity induced superconductivity in TI/superconductor heterostructures. Also, the experimental setup to grow and study TIs at the Physics Department of the University of Connecticut will be presented.

[1] L. Fu, C. L. Kane, and E. J. Mele, Phys. Rev. Lett. 98, 106803 (2007).

[2] X.-L. Qi and S.-C. Zhang, Rev. Mod. Phys. 83, 1057 (2011).

[3] T. Yilmaz, et al., Appl. Surf. Sci. 407, 371 (2017).

Prof. Serge M. Nakhmanson, Department of Materials Science and Engineering, and Institute of Materials Science, University of Connecticut

Mesoscale simulations of ferroic functionalities with finite elements: MOOSE, Ferret and other animals

Ferret is an open-source highly scalable real-space finite-element-method (FEM) based code for simulating transitional behavior of materials systems with coupled physical properties at mesoscale. This code is built on MOOSE, Multiphysics Object Oriented Simulation Environment, and is being developed by a team of collaborators at the University of Connecticut and Argonne National Laboratory. MOOSE allows efficient solving of coupled-physics problems, has a proven record of scaling of execution on up to 10K nodes, and is easily extendable to include new physics and couplings. Real-space FEM approach allows treatment of materials systems possessing complicated geometry and morphology, and evaluation of property dependencies on the system shape, size, microstructure and applied boundary conditions. In this presentation we provide an overview of computational approach utilized by the code, as well as its technical features and the associated software within its tool chain. We also highlight a variety of examples of the code applications, some of which are being pursued in collaboration with a number of different experimental groups. These applications include (a) evaluation of size- and microstructure-dependent elastic and electronic properties of semiconducting core-shell nanostructures; (b) investigation of transitional behavior and topological phases in ferroelectric films, islands, particles and particle-based ferroelectric/dielectic materials; and (c) understanding the workings of photoelectric and electro-optic effects in piezoelectric and ferroelectric materials and nanostructures.

SN acknowledges the efforts of his students John Mangeri, Krishna Chaitanya Pitike and Lukasz Kuna, and senior collaborators S. Pamir Alpay (UConn), and Olle G. Heinonen (ANL), all of whom made major contributions to the projects discussed in this presentation. Funding support from the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program is acknowledged. The SCGSR program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the US Department of Energy. ORISE is managed by ORAU under contract number DE-SC0014664. US National Science Foundation (award number DMR 1309114) is also acknowledged for partial funding of some activities related to the development of the Ferret code.

Dr. Chiara Mingarelli, Center for Computational Astrophysics, Flatiron Institute

Pulsar Timing Arrays: The Next Window to Open on the Gravitational-Wave Universe

Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz to microhertz regime. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in the nanohertz band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent limits which have emerged from international efforts to constrain astrophysical phenomena at the heart of supermassive black hole mergers.

Adam Ginsburg, National Radio Astronomy Observatory, Socorro, New Mexico

High mass star and cluster formation

High mass stars are responsible for most of the photons, heavy elements, and energy in galaxies, thereby driving their evolution. They tend to form in dense environments and clusters, which means we can only observe their formation at relatively large distances. I will discuss observational programs, primarily with ALMA, that show how stars form differently in denser parts of galaxies. At higher densities, more stars form in clusters, more stars form in the vicinity of massive stars, and the stellar initial mass function (IMF) shifts to favor higher masses. ALMA data at high resolution show how the feedback from massive stars shapes their environments. The upcoming ALMA-IMF large program will extend this work, showing how the stellar IMF is shaped throughout our Galaxy.

Dr. Aaron LaForge, Department of Physics, University of Connecticut

Excitation dynamics in helium nanodroplets induced by XUV radiation

As opposed to purely molecular systems where electron dynamics proceed only through intramolecular processes, weakly-bound complexes like helium nanodroplets offer an environment where local excitations can interact with neighboring molecules leading to new intermolecular relaxation mechanisms. Here, we present a systematic, time-resolved study of the excitation dynamics when helium nanodroplets are resonantly excited by XUV free electron laser radiation. At low pulse energy, a single atom is excited leading to the formation of a bubble state which relaxes to the droplet surface on a femtosecond timescale. At high pulse energy, a network of excited atoms is formed within a nanodroplets which then collectively autoionizes with high efficiency. Using the pump-probe technique, we were able to time resolve this process.

John Donoghue, UMass Amherst

A possible QFT pathway for UV complete quantum gravity

This is a study of a renormalizable quantum field theory for gravity. It makes use of a gravitational sector which is weakly coupled at all scales, and a helper Yang Mills gauge theory which becomes strong at the Planck scale. While it has an unstable ghost in the propagator, and other unusual properties, unitarity is satisfied at the one loop level as determined by explicit calculation. Further
explorations will be discussed.

Professor Rainer Weiss, Massachusetts Institute of Technology, 2017 Nobel Prize Winner,
Member of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Scientific Collaboration

Exploration of the Universe with Gravitational Waves

The observations of gravitational waves from the merger of binary black holes and from a binary neutron star coalescence followed by a set of astronomical measurements is an example of investigating the universe by "multi-messenger" astronomy. Gravitational waves will allow us to observe phenomena we already know in new ways as well as to test General Relativity in the limit of strong gravitational interactions -- the dynamics of massive bodies traveling at relativistic speeds in a highly curved space-time. Since the gravitational waves are due to accelerating masses while electromagnetic waves are caused by accelerating charges, it is reasonable to expect new classes of sources to be detected by gravitational waves as well. The lecture will start with some basic concepts of gravitational waves. Briefly describe the instruments and the methods for data analysis that enable the measurement of gravitational wave strains of 10-21 and then present the results of recent runs. The lecture will end with a vision for the future of gravitational wave astrophysics and astronomy.

22nd Annual Katzenstein Distinguished Lecture

Refreshments will be served at 3:00 p.m. outside of GW-38

Dr. Yuya Tanizaki, RIKEN-BNL

Constraints on possible dynamics of QCD by symmetry and anomaly

Low-energy dynamics of Quantum Chromodynamics (QCD) is an important subject for nuclear and hadron physics, but it is a strongly coupled system and difficult to solve. In this situation, symmetry and also anomaly give us an important guide to make a solid conclusion on possible
behaviors of QCD. We will give a brief review on recent development of anomaly matching condition, starting from a simple quantum mechanical example. After that, we explain the newly found anomaly of QCD in chiral limit, and discuss the conclusion of anomaly matching.

Prof. Roger Falcone, University of California, Berkeley and 2018 President of the American Physical Society

Science at High Energy Density and Work of the American Physical Society

Materials taken to extreme densities and temperatures exhibit unique properties due to changes in electronic structure. I will describe experiments, done at facilities that use the world's highest energy lasers and x-ray lasers, to excite such materials and probe their properties. At the end if this talk I will focus on the work of the American Physical Society, in publishing, advocating for science, and reaching out to broader communities.

Dr. Charlotte A. Mason, Harvard-Smithsonian Center for Astrophysics

What Can Galaxies Tell Us About Reionization

The reionization of intergalactic hydrogen in the universe's first billion years was likely driven by the first stars and galaxies. The timeline of reionization is currently uncertain but if it is accurately measured it can unveil the properties of 'first light' sources. Lyman alpha (Lyα) emission from galaxies can potentially probe the intergalactic medium (IGM) at high redshifts but requires modeling physics from pc to Gpc scales. I will introduce a new forward-modeling framework which combines cosmological IGM simulations with interstellar medium models to enable Bayesian inference of the IGM neutral hydrogen fraction from observations of Lyα from galaxies. I will present our new measurements of the neutral fraction at z~7 and z~8 and place them in the context of the reionization history. I will describe ongoing efforts with the HST survey GLASS to build larger spectroscopic samples of galaxies at z>6 to further measure the reionization timeline, and future prospects with JWST.

Prof. J. Brad Marston, Physics Department, Brown University

El Nino as a Topological Insulator: A Surprising Connection Between
Climate and Quantum Physics

Symmetries and topology play central roles in our understanding of physics. Topology, for instance, explains the precise quantization of the
Hall effect and the protection of surface states in topological insulators
against scattering from disorder or bumps. However discrete symmetries and
topology have so far played little role in thinking about the fluid dynamics of oceans and atmospheres. In this talk I show that, as a consequence of the rotation of the Earth that breaks time reversal symmetry, equatorially trapped Kelvin and Yanai waves emerge as
topologically protected edge modes. Thus the oceans and atmosphere of Earth naturally share basic physics with topological insulators. As
equatorially trapped Kelvin waves in the Pacific ocean are an important component of El Nino Southern Oscillation and other climate processes,
these new results demonstrate that topology plays a surprising role in Earth's climate system.

Dr. Jeff Powell, Department of Physics, University of Connecticut

Photoelectron emission from metal and dielectric nanoparticles in intense laser fields

Nanoparticles provide a unique platform to study the mechanisms of light interactions with complex systems, in particular, the motion of electrons driven by strong fields and excitation of plasmonic resonances. Here I report on the systematic analysis of the photoelectron emission from single, isolated, gas-phase, spherical nanoparticles as a function of particle size, composition and laser intensity. Gold, silica (SiO2), and silica core/gold shell nanoparticles ranging in size from 5nm to 750nm were irradiated by 800nm, 25fs laser pulses at 0.2-20 TW/cm2 peak intensities. A high energy velocity-map imaging spectrometer was used to determine the cutoff photoelectron energy for each sample and intensity. Nanoparticle size and composition influence the electron cutoff energy, which provides insight into photoelectron trajectories and rescattering dynamics, both of which are affected by near-field enhancement and plasmonic excitation. In particular, I observe that photoelectrons emitted from gold nanoparticles are much more energetic than those from silica, which, in turn, are much faster than those from isolated atoms or molecules exposed to the same light pulses. This work reveals the complex interplay between the external optical field and the induced near-field of the nanoparticle.

Prof. Dawn Meredith, Department of Physics, University of New Hampshire

Instructor and student resources in the physics course for life science students

Over a decade ago, professionals in life science called for the education for the next generation of practitioners to be more interdisciplinary and quantitative. Physicists listened, and in the last decade we have learned a lot about the students and the potential of this course. I will share some insights about what makes this course different from the course for engineers, best practices and new curricula, and the soon-to-be-live Living Physics Portal that provides community and resources for instructors. In the second part of the talk, I'll discuss research that uncovers some productive cognitive resources that life science students bring to the physics classroom on which new understandings can be built.​

Coffee and tea will be served prior to the talk, at 3:00 p.m., In Room GW-103

Prof. Steve Finkelstein, Department of Astronomy, University of Texas, Austin

Understanding the Reionization of the Universe Now and with JWST

The universe just after the Big Bang was a dark place, while the remnant radiation from the Big Bang cooled, and gas began to pile into dark matter halos. After a few hundred million years, the as-yet unseen first galaxies began to form, and the ionizing radiation produced by their massive stars ionized the intergalactic medium, in a process known as reionization. The search for these first galaxies, and an understanding of the process of reionization, has been a major goal of extragalactic astronomy for decades. While it is commonly assumed that massive stars within star-forming galaxies provide the needed ionizing photons to reionize the intergalactic medium, the commonly assumed ionizing photon escape fractions in the range of 10-50% have thus far exceeded what has been observed (except in a few extreme cases). I will discuss the results of a new semi-empirical model, combining simulated galaxy escape fractions with observed rest-UV galaxy luminosity functions. We find that we can successfully match all observational constraints on reionization by 1) forming stars to physically-motivated halo mass limits; 2) allowing galaxies to be more efficient ionizing photon producers at higher redshift, and 3) allowing a (not strong) contribution from AGNs. This predicts that reionization is a smoother process than previous models, with a predicted volume-averaged ionized fraction of 20% at z=10. JWST will soon dramatically improve our view of the z~10 universe and validate whether significant star-formation is occurring in that epoch, and I will conclude by discussing a recently-approved JWST Early Release Science program which will begin to probe this epoch.

Shany Danieli, Yale University

Hunting low surface brightness galaxies with the Dragonfly Telephoto Array

Dwarf galaxies are a significant component of the galaxy population. Their number density, among other properties, provides strong constraints on theories of galaxy formation, stellar feedback processes, and the distribution and nature of dark matter. However, their low central surface brightnesses makes them difficult to detect and study beyond the Local Group, leading to a biased view of the full galaxy population. To address this problem a new robotic telescope was developed and built, called the Dragonfly Telephoto Array, that is optimized to explore the universe at surface brightness levels below 30 mag/arcsec^2. In this talk I'll describe the technology behind the 1m f/0.4 refractor and present some early results in the dwarf galaxy regime. I will then present our strategy for finding these low surface brightness galaxies as part of the on-going Dragonfly Wide Field Survey that will cover 500 sq. deg. upon survey completion. We will use these data to empirically constrain the Luminosity Function of field galaxies down to the low mass end which is essential for understanding the nature of low-mass dark matter halos.

Shany Danieli is a Physics PhD student at Yale University, working with Prof. Pieter van Dokkum. She specializes in the formation and evolution of dwarf galaxies and Ultra Diffuse Galaxies, both in galaxy groups and in the field (isolated galaxies), using various observational tools such as the Dragonfly Telephoto Array and the Hubble Space Telescope.

Prof. Gerald Dunne, Department of Physics, University of Connecticut

Resurgence and Phase Transitions

Resurgence is a new approach to quantum field theory that combines perturbative and non-perturbative effects in a unified framework. I'll give an overview of the key ideas and discuss applications to phase transitions in physical problems. The main motivation is to find a new way to probe the QCD phase diagram. In this approach, a phase transition is interpreted as a change of dominant saddle in a path integral or partition function. Examples include the Ising model, chiral symmetry breaking in the Gross-Neveu model, the Thirring and Hubbard models, and the large N phase transition in 2d lattice gauge theory.

Dr. Peter D Drummond FAA, Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne, Australia

Testing quantum mechanics with modern technology

Wendell Furry [1] and Sydney Coleman [5] were two of Harvard's most original quantum theorists. What can modern quantum technology contribute to their work? Experimentally tested simulations of opto-mechanics[4] and atom interferometers [3], with thermal noise and losses, will be used to analyse proposals for testing Furry's nonlocal decoherence, and Coleman's QFT tunnelling to the true vacuum. Both these ideas are fundamental to our understanding of the quantum universe. Nonlocal decoherence was proposed in Furry's response to Einstein's EPR paper. Today, this idea is becoming testable for massive objects at low temperatures. Entanglement decoherence and massive Schrodinger cats are testable [4] through an optomechanical memory, simulated using the positive-P representation, thus combining technology at Yale and JILA. Coleman's proposal of a false vacuum models fluctuations in the early universe, leading to large-scale structure in the microwave background. Coleman's ideas will be applied to construct a proposal for a laboratory model of the quantum fluctuations in the 'Big Bang', using a coupled BEC experiment in ultracold 41K, simulated with a Wigner phase-space representation [6].

[1] W. H. Furry, Phys. Rev. 49, 393 (1936).

[2] A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935).

[3] M. Egorov et. al, Phys. Rev. A 84, 021605 (2011).

[4] S. Kiesewetter, R. Y. Teh, P. Drummond and M. Reid, Phys. Rev. Lett. 119, 023601 (2017).

[5] S. Coleman, Phys. Rev. D 15, 2929 (1977).

[6] O. Fialko et. al., J. Phys. B 50 024003 (2017).

Coffee and tea will be served prior to the talk, at 3:00 p.m., In Room GW-103

Jennifer Bergner, Harvard-Smithsonian Center for Astrophysics, Harvard University

Chemical complexity during star and planet formation: new observational and laboratory insights

Planets form by accreting material from a protoplanetary disk, meaning that the inventory of molecules in the disk sets what subsequent chemistry can occur on a newly formed planet. Constraining the organic chemistry in disks and their precursors is therefore key to origins of life studies. I will discuss recent progress in detecting and characterizing simple (HCN and C2H) and complex (CH3CN and HC3N) organic molecules in protoplanetary disks using ALMA, as well as implications for the chemistry at play. As we are sensitivity-limited in the level of molecular complexity that can be detected in disks, observations of organic molecules around low-mass protostars are providing important windows into the initial chemical conditions of disk and planet formation. To complement these observational
approaches, we use laboratory experiments to understand how reactions proceed under conditions of low temperature and low pressure. I will outline our recent work exploring new pathways to chemical complexity in laboratory analogs of
astrophysical ices.

About the speaker: Jennifer Bergner is a graduate student in (Astro)Chemistry at Harvard working with Prof. Karin Oberg at the Harvard-Smithsonian Center for Astrophysics. She is a National Science Foundation graduate research fellow and
specializes in laboratory astrochemistry, focused on the physics and chemistry of interstellar ice analogs.

Dr. Shimshon Kallush, Physics and Optical Engineering Department, ORT Braude College, Karmiel, and The Fritz Haber Center for Molecular Dynamics, The Hebrew University, Jerusalem, Israel

Molecular alignment in hot and cold regimes, and its relationship to quantum coherence

The phenomena of field-free instantaneous quantum revivals of molecular alignment and orientation driven by optical and/or terahertz fields will be introduced. A brief survey over a few applications of the phenomena will be presented within this context:

1. Ultracold photoassociation will be shown to intrinsically contain molecular alignment. Its characteristics and the feasibility to detect directional preferences for the photoassociated species will be discussed.

2. Rotational echoes of alignment under multiple pulses will be shown to lead to unique spatial-temporal structures of the refractive index. Several applications of this feature will be suggested.

3. The quantum picture of alignment raises questions that relate to the ability to embed quantum coherences into thermal quantum systems. The problem of quantification of coherences is defined and some results that predict the ability to induce field-driven coherences will be presented

Dr. Ming Li, Department of Physics, University of Connecticut

High Baryon Densities Achievable in the Fragmentation Regions of High Energy Heavy-Ion Collisions

In high energy heavy-ion collisions, the two colliding nuclei pass through each other leaving behind an almost baryon-free central region. Most of the baryon charges are carried away by the receding nuclear remnants. During the collisions, a large amount of kinetic energy is deposited in the central region where a new form of matter called quark-gluon plasma is formed. At the same time, the colliding nuclei are highly compressed, resulting in very high baryon densities in the nuclear remnants. In this talk, I will explore the high baryon density achievable in the nuclear remnants and study the hydrodynamic evolution of the high baryon density matter.

This seminar was originally scheduled for September 10.

Professor Alexandra Pope, Department of Astronomy, University of Massachusetts Amherst

Rise of dust: Completing our Census of Cosmic Star Formation

Observations at (sub)millimeter wavelengths (~0.25-1.4 mm) provide a unique view of galaxy formation, revealing hidden star formation in the early Universe (a few Gyr after the Big Bang) that cannot be seen at optical wavelengths due to extreme dust obscuration. Previous surveys from single-dish telescopes were sensitive to only the most extreme galaxies forming stars >100 times the rate of the Milky Way, while the more typical galaxies that dominate the total energy budget at these wavelengths remain elusive. I will discuss recent observations of dusty galaxies with the next generation of (sub)millimeter wavelength telescopes -- including the Large Millimeter Telescope (LMT) and the Atacama Large Millimeter Array (ALMA) -- to push studies of dust-obscured activity down to the more typical galaxies that dominate the cosmic star formation history. Finally, I will introduce TolTEC, a revolutionary new camera for the LMT, and the public legacy surveys that will be completed from 2019-2021. These surveys will make a complete census of dust-obscured activity in the Universe.

Coffee and tea will be served prior to the talk, at 3:00 p.m., In Room GW-103 (aka PB-103)

The Physics Graduate Student Association (PGSA) invites all members of the Physics Department to our annual ice cream social event, to introduce our new graduate students and undergraduate majors and welcome everyone back who has recently joined us or returned for the new academic year.

THIS SEMINAR HAS BEEN RESCHEDULED FOR MONDAY, SEPTEMBER 17, 2018

Dr. Ming Li, Department of Physics, University of Connecticut

High Baryon Densities Achievable in the Fragmentation Regions of High Energy Heavy-Ion Collisions

Title: Contributions of Dr. Nora Berrah to the Growth of the Physics Department

Abstract: Dr. Berrah was the Department Head of Physics for the past five years. During that time, she had a major impact on all areas of the department, including important hires in all the major research areas of the department (Particle, Astrophysics, and Nuclear Physics; Atomic, Molecular, and Optical Physics; Condensed Matter Physics), including a new one (Astronomy); encouraging new teaching styles, mentoring early-career faculty, further improving the welcoming climate for undergraduate and graduate students; and raising the profile of the department in the university. Of special interest are four major initiatives she started in Astronomy, Studio Physics, AMO Physics, and Condensed Matter Physics, all of which required considerable effort on her part. In this talk, we will hear about the various hires as well as the four initiatives.