Longtime Science Pioneer Passes Away
Throughout her long life, Cynthia Peterson educated and enriched her family, her students, and her community through science, discovery, and a lifelong enthusiasm for teaching prospective scientists. Through community outreach and during her many years as a professor, Cynthia taught many that wonderment can be found simply by looking up at the night sky.
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New Physics Faculty: Erin Scanlon
Erin Scanlon joins our Department in fall 2020 as Assistant Professor in Residence at the Avery Point Campus. Erin comes to UConn with an impressive track record of university teaching experience and scholarship in physics education research (PER). After earning a master’s degree in physics from Georgia Institute of Technology, Erin joined the faculty at […]
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New Physics Faculty: Chris Faesi
We are very excited to extend a warm welcome to a new UConn Physics Faculty member, Dr. Christopher Faesi. Chris is an astrophysicist, specializing in both observational work and modelling, primarily in the study of star formation. He got his PhD at Harvard University, followed by a postdoc at the Max Planck Institute for Astronomy […]
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Prof. Kyungseon Joo named Chair of CLAS Collaboration at Jefferson Lab
Kyungseon Joo, a professor of physics, has been named Chair of the CLAS Collaboration, one of the largest international collaborations in nuclear physics. CLAS involves 50 institutions from 9 countries and has about 250 collaborators. The collaboration recently completed the upgrade of the CEBAF Large Acceptance Spectrometer (CLAS12) for operation at 11 GeV beam energy […]
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Physics Department Joins APS-IDEA Network
The Physics Department’s Diversity & Multiculturalism Committee (DMC) was accepted into the APS Inclusion, Diversity and Equity Alliance (APS-IDEA). Despite years of efforts on local and national levels, the diversity in many physics departments is not reflective of the diversity nationwide. Our department is no exception in this regard. The new APS initiative was created […]
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Prof. T. Blum, Department of Physics, University of Connecticut, "Lattice QCD at UConn", Graduate Student Seminar12:15pm
9/18
Prof. T. Blum, Department of Physics, University of Connecticut, "Lattice QCD at UConn", Graduate Student Seminar
Friday, September 18th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof. T. Blum, Department of Physics, University of Connecticut
Lattice QCD at UConn
I will give a brief introduction to the Standard Model of Particle Physics, and Quantum Chromodynamics (QCD) in particular. I will then describe how we solve QCD using large scale numerical simulations. I will finish with a few current and important examples. -
Graduate Student Saman Bastami, Department of Physics, University of Connecticut, "Studies on Hadron Structure through Transverse-Momentum-Dependent Parton Distribution Functions", PhD Dissertation Defense1:15pm
9/11
Graduate Student Saman Bastami, Department of Physics, University of Connecticut, "Studies on Hadron Structure through Transverse-Momentum-Dependent Parton Distribution Functions", PhD Dissertation Defense
Friday, September 11th, 2020
01:15 PM - 03:15 PM
Storrs Campus Video meeting
Graduate Student Saman Bastami, Department of Physics,
University of Connecticut
Studies on Hadron Structure through Transverse-Momentum-Dependent Parton Distribution Functions
The detailed description of hadrons in terms of quarks and gluons, the fundamental degrees of freedom of Quantum Chromodynamics, is an open problem. Important aspects of hadron structure can be studied in certain deep-inelastic high-energy processes which have revealed important insights about the longitudinal momentum distributions of quarks and gluons inside hadrons. Our knowledge of the three-dimensional structure is still very limited. Transverse momentum dependent parton distribution functions (TMDs) are one of the main tools to study the transverse structure of hadrons through processes such as semi-inclusive deep inelastic scattering SIDIS) or the Drell-Yan process. This dissertation is dedicated to phenomenological and model studies of TMDs.
All spin and azimuthal asymmetries of the lepton-nucleon SIDIS are calculated at leading- and subleading twist exploring the so-called "Wandzura-Wilczek-type" approximation which consists in a systematic neglect quark-gluon correlations. The results are obtained using available phenomenological information on TMDs as well as constraints from state-of-the-art lattice QCD calculations, and compared to the experimental data from HERMES, COMPASS and Jefferson Lab.
The asymmetries of the pion-induced Drell-Yan process with polarized protons are studied at leading twist. The information about TMDs is taken from non-perturbative calculations in the lightfront constituent quark model, the spectator model and, where available, phenomenological extractions of TMDs. The results are compared to recent data from the first polarized pion-nucleon Drell-Yan experiment performed by the COMPASS Collaboration at CERN, and predictions for future experiments are made.
The "covariant parton model", an effective hadronic model based on the intuitive parton model concept, is extended and formalized. This allows one to compute all time-reversal-even TMDs of leading and subleading twist in a systematic way. This model naturally supports the Wandzura-Wilczek-type approximations and predicts several non-trivial relations between TMDs, many of which are supported in other model frameworks and can be tested in experiments. Applications and limitations of the model are discussed.
Meeting video link: https://zoom.us/j/96866754697?pwd=NEM1WUt3VkxhbVdQQWdacVVubHNvQT09 -
Prof. D. McCarron, Department of Physics, University of Connecticut, "A quantum-leap towards next generation technologies", Graduate Student Seminar12:15pm
9/11
Prof. D. McCarron, Department of Physics, University of Connecticut, "A quantum-leap towards next generation technologies", Graduate Student Seminar
Friday, September 11th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof. D. McCarron, Department of Physics, University of Connecticut
A quantum-leap towards next generation technologies
Recent progress manipulating quantum systems has led to a second quantum revolution that is developing new technologies that leverage the laws of nature at small scales. This talk will give an overview of some of these new technologies alongside their applications - with an emphasis on ultracold systems cooled to one millionth of a degree above absolute zero. I will draw links between these applications and my own research program before giving a brief summary of our experimental progress.
Research Group URL: http://themccarrongroup.com -
Doctoral Dissertation Oral Defense of Saman Bastami1:30pm
9/7
Doctoral Dissertation Oral Defense of Saman Bastami
Monday, September 7th, 2020
01:30 PM - 03:00 PM
Other Zoom
Studies on Hadron Structure through Transverse Momentum Dependent Parton Distribution Functions -
Graduate Student Brandon A. Clary, Department of Physics, University of Connecticut, "Exclusive Phi Production Beam Spin Asymmetry Measurements with CLAS12", PhD Dissertation Defense9:30am
8/21
Graduate Student Brandon A. Clary, Department of Physics, University of Connecticut, "Exclusive Phi Production Beam Spin Asymmetry Measurements with CLAS12", PhD Dissertation Defense
Friday, August 21st, 2020
09:30 AM - 11:30 AM
Storrs Campus Video meeting
Graduate Student Brandon A. Clary, Department of Physics,
University of Connecticut
Exclusive Phi Production Beam Spin Asymmetry Measurements with CLAS12
Measurements of the beam spin asymmetry (BSA) of the exclusive electroproduction of the vector phi(1020) meson through its decay into charged Kaons have been performed. The data set used was based on the RG-A run period from the recently upgraded CEBAF Large Acceptance Spectrometer (CLAS12) in Hall B at Jefferson National Lab (JLab). The run period used a 10.6 GeV longitudinally polarized electron beam and an unpolarized hydrogen target. The available statistics collected allow for detailed studies of the W, -t, xB, and Q2 dependencies of the BSA amplitudes from vector phi meson production. The BSA measurements will shed light on the exchange mechanisms responsible for phi production at JLab energies. In this dissertation, a non-zero BSA is observed, which suggests a possible enhancement of pseudo-scalar exchange mechanism near phi production threshold. Therefore, the non-zero BSA may be a result of the interference of the pseudo-scalar exchange mechanism with a scalar one. Ultimately, information on the dominant exchange mechanism will aid in the development of a Generalized Parton Distribution (GPD) based description of these processes in the context of hard to soft transition.
Webex link: https://uconn-cmr.webex.com/uconn-cmr/j.php?MTID=m0844eee0d13477ad76f35797ae8467db -
Dr. D. Farfurnik, University of Maryland, "Enhancing the coherence properties of quantum dots toward quantum photonic applications", Condensed Matter Physics Seminar10:00am
7/14
Dr. D. Farfurnik, University of Maryland, "Enhancing the coherence properties of quantum dots toward quantum photonic applications", Condensed Matter Physics Seminar
Tuesday, July 14th, 2020
10:00 AM - 11:00 AM
Storrs Campus online
Dr. D. Farfurnik, University of Maryland
Enhancing the coherence properties of quantum dots toward quantum photonic applications
Self-assembled Quantum Dots (QD) exhibit some of the best single photon emission properties, including nearly ideal efficiency and indistinguishability. As such, and considering their compatibility with nanofabrication techniques, on-chip integration of QDs as single photon emitters and non-linear components plays a key role in integrated photonic-based information processing and may pave the way toward the creation of quantum networks. Manipulating and storing quantum information utilizing QD spins, however, is limited by their short coherence times originating from interactions with a nuclear bath. In this talk, I will describe our approaches for addressing this challenge: First, the application of dynamical decoupling (DD) pulse sequences prolongs the coherence times by decoupling the QD spins from the environment. While the performance of such protocols is often limited by the accumulation of pulse imperfections, arbitrary spin control enabling composite and concatenated sequencing could further enhance the achievable spin control fidelities [1]. Such a sequencing is implementable by driving a Lambda system of the QD utilizing an optical signal arbitrarily modulated by a temperature-stabilized electro optical modulator (EOM). I will present a recent experimental demonstration of such a control [2], our analysis for optimizing the EOM working point for enhancing the achievable optical rotation Rabi frequencies, as well as the efficiency of the protocol for QDs strongly coupled to L3 photonic crystal cavities. Second, the resulting coherence properties may be further enhanced by utilizing molecules of coupled QDs (QDM), which offer a singlet-triplet ground state decoherence-free subspace [3]. Beyond the promising combination of such a subspace with the application of DD sequences, leveraging the isolated optical transitions of the QDM may offer single-shot spin readout capabilities. I will present our approach for implementing such a spin readout incorporating microwave pi-pulses, its experimental feasibility utilizing optimally designed transmission lines, and the expected readout fidelities based on the achievable microwave Rabi frequencies [4].
[1] D. Farfurnik et al., ``Optimizing a dynamical decoupling protocol for solid-state electronic spin ensembles in diamond'', Phys. Rev. B 92, 060301(R) (2015)
[2] J.H. Bodey et al., ``Optical spin locking of a solid-state qubit'', npj Quantum Information 5, 95 (2019)
[3] D. Kim et al., ``Ultrafast optical control of entanglement between two quantum-dot spins'', Nat. Phys. 7, 223--229 (2011)
[4] D. Farfurnik et al., ``Experimental realization of time-dependent phase-modulated continuous dynamical decoupling'', Phys. Rev. A 96, 013850 (2017)
Zoom Meeting: https://kth-se.zoom.us/j/61809414846 -
Graduate Student Daniel McNeel, Department of Physics, University of Connecticut, "Shape Coexistence in \(^{28}\)Mg: Structure of a Transitional Nucleus", PhD Dissertation Defense1:00pm
6/11
Graduate Student Daniel McNeel, Department of Physics, University of Connecticut, "Shape Coexistence in \(^{28}\)Mg: Structure of a Transitional Nucleus", PhD Dissertation Defense
Thursday, June 11th, 2020
01:00 PM - 03:00 PM
Storrs Campus Video meeting
Graduate Student Daniel McNeel, Department of Physics,
University of Connecticut
Shape Coexistence in \(^{28}\)Mg: Structure of a Transitional Nucleus
The structure of nuclei outside the region of stability is an area of ongoing experimental research. Recent investigations in the region around \(^{32}\)Mg have discovered inversions in the usual ordering of shell model states. From these discoveries, theories of the evolution towards this "island of inversion" predict low-lying deformed intruder states for several nuclei in the region. One such nucleus, which exists in the region of transition between the normal and inverted hierarchies, is \(^{28}\)Mg. In this nucleus the ground state is expected to be mixed, i.e. it is a superposition of nearby \(0^+\) neutron pairing configurations. An excited intruder \(0^+\) state will have a different configuration and shape than surrounding states, a property known as shape coexistence.
Multi-nucleon transfer is known to be sensitive to the static deformation of a nucleus. It is also sensitive to both the amplitude and phase of configuration mixed states, and enhances transfer to those states which are similar to the ground state of the target plus two nucleons in single particle orbitals. This makes it a valuable tool to investigate the properties of \(^{28}\)Mg. The two-neutron adding reaction \(^{26}\)Mg(t,p)\(^{28}\)Mg has been used to study the properties of the ground state and excited \(0^+\) states. This experiment was carried out at Argonne National Laboratory using the HELIcal Orbit Spectrometer (HELIOS). HELIOS was designed to overcome the difficulties of measuring reactions in inverse kinematics. Experiments in inverse kinematics consist of a heavy particle, in this case \(^{26}\)Mg, incident on the light particle (\(^3\)H).
Because multi-nucleon transfers are more complex than single particle transfers, a calculation of the nuclear structure must guide the understanding of which configurations will be strongly populated. Shell model calculations have been used to evaluate the structure related transfer amplitudes, which were used as input into Distorted Wave Born Approximation (DWBA) calculations for the reaction. The results of this analysis are the relative contributions of different configurations to the ground state and excited \(0^+\) states, which provide a stringent test of the theoretical prediction of shape coexistence and intruder states.
Video link: https://uconn-cmr.webex.com/meet/dgm14002 -
Graduate Student Matthew Phelps, Department of Physics, University of Connecticut, "Cosmological Fluctuations in Standard and Conformal Gravity", PhD Dissertation Defense10:00am
6/2
Graduate Student Matthew Phelps, Department of Physics, University of Connecticut, "Cosmological Fluctuations in Standard and Conformal Gravity", PhD Dissertation Defense
Tuesday, June 2nd, 2020
10:00 AM - 12:00 PM
Storrs Campus Video meeting
Graduate Student Matthew Phelps, Department of Physics,
University of Connecticut
Cosmological Fluctuations in Standard and Conformal Gravity
In the theory of cosmological perturbations, extensive methods of simplifying the equations of motion and eliminating non-physical gauge modes are required in order to construct the perturbative solutions. One approach, standard within modern cosmology, is to decompose the metric perturbation into a basis of scalars, vectors, and tensors defined according to their transformation behavior under three-dimensional rotations (the S.V.T. decomposition). By constructing a projector formalism to define the basis components, we show that such a decomposition is intrinsically non-local and necessarily incorporates spatially asymptotic boundary conditions. We continue application of the S.V.T. decomposition and solve the fluctuation equations exactly within standard cosmologies as applied to both Einstein gravity and conformal gravity, finding that in general the various S.V.T. gauge-invariant combinations only decouple at a higher-derivative level. To match the underlying transformation group of General Relativity and thus provide a manifestly covariant formalism, we introduce an alternate scalar, vector, tensor basis with components defined according to general four-dimensional coordinate transformations. In this basis, the fluctuation equations greatly simplify, where one can again decouple them into separate gauge-invariant sectors at the higher-derivative level. In the context of conformal gravity, we use similar constructions to solve the fluctuation equations exactly within any geometry that is conformal to flat and show that in a radiation era Robertson-Walker cosmology, fluctuations grow as \(t^4\).
Video Meeting URL: https://uconn-cmr.webex.com/meet/map14010