Breaking Up is Hard To Do (for Electrons in High Temperature Superconductors)
Physicists used to think that superconductivity – electricity flowing without resistance or loss – was an all or nothing phenomenon. But new evidence suggests that it’s not so clear cut, at least in copper oxide superconductors. “If we understood why copper oxide is a superconductor at such high temperatures, we might be able to synthesize a better one”, says UConn physicist Ilya Sochnikov. Sochnikov and his colleagues at Rice University, Brookhaven National Lab and Yale recently figured out part of that puzzle, and they report their results in the latest issue of Nature.
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Daniel McCarron wins NSF Early Career Award
Daniel McCarron, assistant professor of physics, the College of Liberal Arts and Sciences, will receive $645,000 over five years for his work on the development of techniques to trap large groups of molecules and cool them to temperatures near absolute zero. The possible control of molecules at this low temperature provides access to new research applications, such as quantum computers that can leverage the laws of quantum mechanics to outperform classical computers.
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Meet the Researcher: Carlos Trallero
When Carlos Trallero started his academic career in physics, he had no idea he would become a pioneer in a field of research that uses high-power lasers to investigate atomic and molecular physical phenomena. Originally from Cuba, where there isn’t much funding for experimental research, Trallero began his academic career by studying theoretical physics. But as a senior graduate student at Stony Brook University, he got the chance to work in a lab doing experimental work and quickly recognized it was his true passion.
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International Summer School “Strong interactions beyond simple factorization”
May 27-June 5 UConn Physics Department hosted an international summer school Strong interactions beyond simple factorization: collectivity at high energy from initial to final state. The school was supported by an NSF grant to Prof. Kovner and was devoted to modern approaches to the physics of high energy hadronic and heavy ion collisions.
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Amelia Henkel, Graduating President of the Undergraduate Women in Physics Club, speaks about her time at UConn
Amelia Henkel, graduating Double Major in Physics and Human Rights, and President of the Undergraduate Women in Physics Club, speaks on the CLAS website about her passion for physics and human rights, and how she mastered challenges in her remarkably interdisciplinary curriculum. “We really need to interact with other disciplines,” says Amelia, “because that’s […]
[Read More]Recent Events
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Prof. P. Mannheim, Department of Physics, University of Connecticut, "Quantum mechanics off the beaten track", Graduate Student Seminar12:15pm
9/13
All Events »Prof. P. Mannheim, Department of Physics, University of Connecticut, "Quantum mechanics off the beaten track", Graduate Student Seminar
Friday, September 13th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. P. Mannheim, Department of Physics, University of Connecticut
Quantum mechanics off the beaten track
We discuss some non-conventional options for quantum theory. We show that
it is not always possible to write the momentum operator as the familiar derivative operator \(-id/dx\) where x is real, and discuss what one should then do. We show that basis states do not need to be normalizable to be complete, and even if normalizable do not have to obey the standard Dirac
completeness relation \(\sum |n>
Prof. B. Spivak, Department of Physics, University of Washington, " Anomalous metals", Condensed Matter Physics Seminar2:00pm
9/10
Prof. B. Spivak, Department of Physics, University of Washington, " Anomalous metals", Condensed Matter Physics Seminar
Tuesday, September 10th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Prof. B. Spivak, Department of Physics, University of Washington
Anomalous metals
The observation of metallic ground states in a variety of two-dimensional electronic systems poses a fundamental challenge for the theory of electron fluids. I will analyze evidence for the existence of a regime, which we call the "anomalous metal regime," in diverse 2D superconducting systems driven through a quantum superconductor to metal transition by tuning physical parameters such as the magnetic field, the gate voltage in the case of systems with a MOSFET geometry, or the degree of disorder. The principal phenomenological observation is that in the anomalous metal, as a function of decreasing temperature, the resistivity first drops as if the system were approaching a superconducting ground state, but then saturates at low temperatures to a value that can be orders of magnitude smaller than the Drude value. The anomalous metal also shows a giant positive magneto-resistance. This behavior is observed in a broad range of parameters. I will exhibit, by theoretical solution of a model of superconducting grains embedded in a metallic matrix, that as a matter of principle such anomalous metallic behavior can occur in the neighborhood of a quantum superconductor-metal transition. However, I will also argue that the robustness and ubiquitous nature of the observed phenomena are difficult to reconcile with any existing theoretical treatment and speculate about the character of a more fundamental theoretical framework. Prof. N. Berrah, Department of Physics, University of Connecticut, "Towards Making Molecular Movies", Graduate Student Seminar12:15pm
9/6
Prof. N. Berrah, Department of Physics, University of Connecticut, "Towards Making Molecular Movies", Graduate Student Seminar
Friday, September 6th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. N. Berrah, Department of Physics, University of Connecticut
Towards Making Molecular Movies
In the past decade, improved laser technology from the Infrared to the X-ray regime has allowed scientists to advance the frontiers of time-resolved ultrafast science. Table-top ultrafast lasers as well as Free Electron Lasers (FELs) science have been identified as one of the highest priority for funding agencies.
We have pursued photo-induced molecular dynamics research with complementary table-top as
well as XUV and X-ray FELs with the ultimate goal of making molecular movies. These movies
follow the electronic and nuclear dynamics induced by the absorption of photons by molecules that occur because of the coupling between the electronic and nuclear motion in the molecules. This coupling first leads to attosecond electron excitation within the molecules, followed by nuclear motion in the femtosecond range, eventually resulting in the formation and breaking of chemical bonds on the picosecond timescale. Research highlights will be presented.
Dr. Molly Gallagher, Department of Physics,University of Connecticut, "Mapping Extragalactic Dense Molecular Gas: Ties to Environment and Star Formation ", Astronomy Seminar2:00pm
9/4
Dr. Molly Gallagher, Department of Physics,University of Connecticut, "Mapping Extragalactic Dense Molecular Gas: Ties to Environment and Star Formation ", Astronomy Seminar
Wednesday, September 4th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Molly Gallagher, Department of Physics,University of Connecticut
Mapping Extragalactic Dense Molecular Gas: Ties to Environment and Star Formation
Gas density plays an important role in galactic evolution via its connection to star formation. Yet because dense gas is difficult to observe, we are only beginning to explore how interstellar gas density and its relationship to the star formation rate depend on galactic environment. We will explore how gas density, star formation rate, and galactic environment interact on scales ranging from Galactic scale down to the scale of individual molecular clouds. This work relies on new dense gas observations of nearby spiral galaxies from the Atacama Large Millimeter/submillimeter Array (ALMA). Prof. V. Kharchenko, Department of Physics, University of Connecticut, "Non-equilibrium Processes in Atomic Science, Astrophysics, and Biology", Graduate Student Seminar12:15pm
8/30
Prof. V. Kharchenko, Department of Physics, University of Connecticut, "Non-equilibrium Processes in Atomic Science, Astrophysics, and Biology", Graduate Student Seminar
Friday, August 30th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. V. Kharchenko, Department of Physics, University of Connecticut
Non-equilibrium Processes in Atomic Science, Astrophysics, and Biology
Non-equilibrium processes arise in transitions between different steady /equilibrium states. Experimental and theoretical investigations of these processes are most formidable tasks for researches in various scientific disciplines, including quantum mechanics, plasma physics, astrophysics, climate change, and biology. Examples of theoretical analysis of non-equilibrium processes in atomic physics, astrophysics, and biology will be discussed and current research projects will be described.
Dr. Jan M Rost, Max Planck Institute for the Physics of Complex Systems, Dresden, Germany, Atomic, Molecular, and Optical Physics Seminar2:00pm
8/21
Dr. Jan M Rost, Max Planck Institute for the Physics of Complex Systems, Dresden, Germany, Atomic, Molecular, and Optical Physics Seminar
Wednesday, August 21st, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Jan M Rost,
Max Planck Institute for the Physics of Complex Systems,
Dresden, Germany
Sculpting electron dynamics through its environment
Interfacing an electron with a well-controlled environment can generate unusual dynamics, in particular if the electron is easily polarizable. The Rydberg Composite, a highly excited Rydberg electron whose spatial density encompasses many atoms or molecules on sites of a designed spatial lattice is one example. We will show that a 2D Composite with a two-dimensional lattice in form of an atomic monolayer has a particularly reach electron spectrum which features energy bands and exhibits regular as well as chaotic features depending on the ratio of lattice spacing and the wavelength of the Rydberg wave function. Possibilities for experimental realizations in the ultracold will be discussed.
The second part of the talk concerns noisy photo electron spectra as generated, e.g., by short and intense SASE free electron laser pulses. Learning the corresponding electron dynamics with a deep neural network by introducing synthetic Hamilton matrices, we can purify the spectrum as if it would have been created with a normal Gaussian pulse. Perspectives of this novel way to construct ultrafast electron dynamics from given noisy spectra will be discussed. Prof. Keith Horne, University of St. Andrews, "Echo Tomography of Black Hole Accretion Flows in Active Galactic Nuclei", Special Astronomy Seminar2:00pm
7/26
Prof. Keith Horne, University of St. Andrews, "Echo Tomography of Black Hole Accretion Flows in Active Galactic Nuclei", Special Astronomy Seminar
Friday, July 26th, 2019
02:00 PM - 03:00 PM
Storrs Campus Gant West P121
Prof. Keith Horne,
University of St. Andrews
Echo Tomography of Black Hole Accretion Flows in Active Galactic Nuclei
Echo Tomography uses light travel time delays to resolve micro-arcsecond structure of black hole accretion flows in active galactic nuclei. I will discuss methods used to map the temperature-radius profile of black hole accretion discs, and to construct velocity-delay maps that probe the geometry, kinematics and ionisation structure of the associated broad emission-line regions. In particular, I will present results from the 2014 STORM campaign using HST, Swift, and ground-based telescopes to monitor spectral variations in the Seyfert galaxy NGC 5548. I will discuss anomalous behaviour observed during the campaign, and present a determination of the inclination and temperature-radius profile of its accretion disc and velocity-delay maps exhibiting evidence for an inclined Keplerian flow extending from 2 to 20 light days. Tilting the inner disc to align with black hole spin may help to address several features we are seeing in the reverberation mapping studies.
Dissertation Defense, Niraj Ghimire- Density Matrix Renormalization Group studies of interacting dipoles in a zigzag chain- Ph. D. defense11:00am
6/26
Dissertation Defense, Niraj Ghimire- Density Matrix Renormalization Group studies of interacting dipoles in a zigzag chain- Ph. D. defense
Wednesday, June 26th, 2019
11:00 AM - 01:00 PM
Storrs Campus Gant West Room 103-A
Dissertation Defense
Niraj Ghimire
Physics Department
University of Connecticut
"Density Matrix Renormalization Group studies of interacting dipoles in a zigzag chain"
The goal of my research is to simulate quantum mechanics, which is known to be a very challenging problem even for the most advanced supercomputers of today. The system I have chosen consists of molecular dipoles in a quasi-one-dimensional optical lattice. For the first part of the talk, I will discuss the situation where the dipoles are polarized in the plane of the lattice at half-filling and double occupancy is not allowed on any lattice sites. The dipoles can hop around between sites and the interactions between them can be attractive or repulsive, with the hopping and interaction allowed up to second neighbors. I am particularly interested in the zero-temperature quantum phases induced by geometrical frustration, a situation where not all the interactions are satisfied. By mapping the dipoles in this lattice to a spin-1/2 model and by using the numerical approximation method known as density matrix renormalization group (DMRG), I have studied this system and produced a complex phase diagram.
For the second part of the talk, I will discuss the situation where a dipole is trapped in each lattice site such that the dipole moment vector can be oriented in any direction. The dipoles interact with one another via dipole-dipole potential and also interact with the external field, but they do not hop around between lattice sites. I will talk about some results for this classical model. Then I will explain how I have mapped it to a spin-2 model (which is quantum mechanical) and explain some results obtained using DMRG.
Major Advisor: Dr. Susanne Yelin
Wednesday, June 26, 2019
11:00 AM
Gant Science Complex
GW-103A