Department of Physics & Astronomy at the University of Utah

The Department of Physics & Astronomy engages in theoretical and experimental research that spans a broad spectrum of modern physics. Our commitment to excellence and success in research is reflected in the strong international reputations of our faculty and programs. The Department of Physics & Astronomy provides research in these areas:

Below is an overview of these research areas. Use the menu on the left to view detailed information about our various research groups.

Astrophysics & Observational Astronomy

Astronomy is a major scientific discipline that remains largely unexplored, yet astronomy is one of the most high-profile specialties in modern science. It receives substantial public attention through generous media coverage, and is well funded by NASA and the NSF. Astronomy complements our existing world-class research programs in theoretical astrophysics, gamma-ray astronomy and cosmic ray physics. Also, the study of astronomy in the 21st century is interdisciplinary, often involving computer science, geology, geophysics, meteorology, biology, chemistry, and mathematics.

The department is very active in high-energy astrophysics, cosmology, particle astrophysics, astrophysical black holes and planet formation. Worldwide international collaborations are the norm. Optical, infrared, X-ray and neutrino astronomy resonates well with current research efforts. New research facilities are under study in Southern Utah and have generated the interest of neighboring institutions such as the University of Nevada at Las Vegas.
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Astrophysics: Relativity & Cosmology

High-energy physicists investigate the most fundamental elements and interactions in nature. Astrophysicists study celestial bodies such as stars and galaxies by observing their light emissions and particles. These two fields operate on very different scales: one deals with subatomic particles, the other with the Universe at large. Yet they intertwine when addressing some of our most profound scientific questions:

What is the origin & fate of the universe?
How was the universe created?
Are there other planets in the universe that support life?
What exactly is “dark matter” & how does it influence the formation, rotation, & evolution of galaxies?
What is the nature of the dark energy that drives the accelerating expansion of the universe?

Researchers at the University of Utah’s Physics & Astronomy Department are carrying out large-scale computer calculations to recreate the conditions of the quark-gluon plasma. We are able to study the formation of protons and neutrons as the Universe cooled. Such information is vital to our understanding of how the Universe came into being.
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Biophysics

The nano-optics group (Gerton) is advancing the boundaries of bioimaging. This work proceeds in collaboration with groups in the Biology and Chemistry departments. The research aims to optimize nanoscale imaging performance in aqueous environments and to ultimately image biomolecular network structures (with the current focus on ESCRT network) with single molecule sensitivity.

Another group (Saffarian) is studying the process by which a new enveloped virus is created on the membrane of its host cell. An enveloped virus similar to influenza or HIV needs to incorporate its genome and many different proteins to be infectious. How all these components are packaged into a new virus; and how the fission from cellular membrane works; are still open questions. There are several groups at university of Utah pursuing these questions using biochemical, crystallographic as well as genetic approaches. In Saffarian lab viral genetic as well as high resolution optical microscopy and fluorescence fluctuation spectroscopy in live cells are used to investigate these questions.

A third group (Vershinin) studies the properties of molecular motors, such as kinesins and dyneins. These proteins are responsible for a wide variety of cargo transport in cells, from single molecules to the largest intracellular assemblies. The group’s focus is on how these motors work together, how they are regulated, and how their functioning is disrupted or altered in various diseases. Biophysics techniques, such as optical trapping and fluorescence microscopy are the primary tools for these investigations.

The biophysics efforts within the department are complemented by strong collaborative efforts throughout the campus (www.biophysics.utah.edu). Equipment and expertise is routinely shared between groups in the College of Science, School of Medicine, School of Pharmacy, and College of Engineering.
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Cosmic Rays

Surrounding the Earth is a constant shower of subatomic particles called cosmic rays. Many originate from our own sun, but some cosmic rays come from far more distant and mysterious origins. The Telescope Array Project is designed to study the rarest, most mysterious, and highest energy cosmic rays. Over time scientists hope to unravel the nature of these mysterious visitors, their origins, and to uncover new knowledge about universe through which they traveled to arrive here at Earth.

The highest energy cosmic rays, called ultra-high energy cosmic rays, are incredibly rare. In one hundred years only one or two will strike within an area as large as a small town. When a high energy comic ray reaches the Earth it enters the upper atmosphere and collides with an air molecule. This collision creates new particles. Each new particle carries part of the energy from the original cosmic ray. The new particles travel a short distance and then collide with air molecules creating still more new particles. While the shower is sweeping through the air it excites the air molecules which fluoresce giving off ultraviolet light. This is the same process that is used to create light in a fluorescent light bulb. The entire air shower from start to finish lasts less than 100 millionths of a second.

Scientists from the University of Utah cosmic ray group are also investigating new methods to detect and measure ultra-high energy cosmic rays. One possibility is the use of radar. As an air shower sweeps through the atmosphere it ionizes some of the air molecules. Radar signals should reflect from the ionized trails created by the passing air shower. Tests are currently underway at the Telescope Array Project to evaluate this possibility. If successful, the next step will be to contrast and calibrate this new method of observation against the well established measurements from air fluorescence and the ground array. The Telescope Array Project is uniquely suited for these new experiments.

The University of Utah has a long and distinguished history leading research into these extremely rare and mysterious visitors from space. International collaborations like the Telescope Array Project are helping to ensure the University of Utah remains a world leader in the new and growing field of astroparticle physics.
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Experimental Condensed Matter Physics

The department has a large and diverse program in the area of experimental condensed matter (solid state) physics. A variety of experimental techniques are employed in these studies, including nuclear magnetic resonance, electron paramagnetic resonance, and optically detected magnetic resonance techniques.

The optical properties of solids are being studied (Vardeny, Gellerman). Picosecond pulsed laser systems are used to study the ultrafast response of conducting polymers (organic chains with remarkable properties, including in some cases the existence of excitations with sub- integral charge), semiconductors, amorphous solids, fullerenes (the exotic carbon balls, e.g. C60, named after Buckminster Fuller), and high-Tc superconductors. Research is also being done in the nonlinear optical properties of solids as applied to fast optical switches (which may well constitute the logic gates of future generations of computers).

Utah is recognized as one of the leaders in the development of tunable infrared lasers, which are being used here to study the electronic properties of various types of defects in insulating ionic and molecular solids. These defects are in part being explored as potential "memory elements" for use in future high density optical information storage devices.

Much of the optical research is done at the Dixon Laser Institute of the University of Utah, formed in 1984 to facilitate collaborations in laser applications research among the Colleges of Science, Engineering, and Medicine. The institute provides experimental research support for visiting scholars and serves as a center for the discussion of optical effects in a variety of materials. In addition, this Institute will play an important role in the department's Medical Physics Program. Besides encouraging novel interdisciplinary research programs, this Institute provides centralized, shared laser resources that expand the potential of each individual researcher.

Low-temperature research (Symko) is primarily focused on macroscopic quantum tunnelling in long Josephson junctions using a 3He-4He dilution refrigerator, and on fluxon dynamics in long junctions. This is of importance in the applications of long Josephson junctions in ultra high speed electronics; such junctions are fabricated for high frequency oscillators. Single electron tunnelling in mesoscopic junctions is also being investigated. The application of the thermoacoustic effect to refrigeration (cooling with sound waves) is also being developed for electronic devices.

An investigation of a wide range of surface phenomena is being performed with the newly developed Scanning Probe Microscopies (C. Williams). These studies range from the nanometer scale visualization and measurement of the properties of semiconductors and insulators to the visualization of single molecules. These new microscopies (atomic force microscopy, scanning capacitance microscopy, electrostatic force microscopy, etc.) are related to the scanning tunnelling microscope (STM) which is capable of imaging the surface structure of solids at the single atom level. These techniques, some of which are being developed in the department, have tremendous potential for application in nearly all the physical sciences. Currently, investigations are being performed to study impurities and charged defects in semiconducting systems and electrostatic charge effects on the chemical properties of molecular systems.
Utah MRSEC

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Medical Physics

Medical Physics is the branch of physics focusing on the broad and diverse application of physics to health care. While medical physics has a role to play in many aspects of medicine, the primary areas of focus are medical imaging (X-ray, MRI, CT, PET, SPECT) and radiation therapy (including both external beam radiotherapy and nuclear medicine treatments with radioactive isotopes). The medical physicist exploits the properties of electromagnetism and radiation interactions with matter to elicit both diagnostic information (imaging) and therapeutic responses in patients with a wide variety of diseases.

The Medical Physics Program offers training and research through a variety of courses and research positions in the laboratories of the program faculty. As health care advances toward new and improved therapies, medical imaging and targeted therapies are playing ever increasing roles in personalized medicine. This is a long term growth area with exciting applications of physics principles to solve real world health care problems.
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Particle Physics

Studies of the behavior of quantum chromodynamics form a major part of the efforts of the particle theory group. In lattice gauge calculations (DeTar) the quantum fields describing quarks and gluons are represented at discrete points in space and time. With such an approximation it becomes possible to carry out a numerical simulation of QCD and solve problems that have not yet

yielded to a pencil-and-paper approach. By extrapolating the behavior of the system as the discrete lattice spacing is reduced (approximating continuous spacetime), it is possible to show that QCD indeed is capable of accounting for quark and gluon confinement. It is also possible to make predictions about the high-temperature behavior of quark-gluon plasmas. These simulations are carried out on the largest computers available in the United States.

Using an analogue to the low-energy behavior of bound heavy quark states, that of dual superconductors (in which it is the electric flux rather than the magnetic flux that is confined), effective interaction potentials for heavy quarks have been derived. With these potentials, QCD can be directly applied to the problem of the calculation of the heavy quark masses.

Recent investigations of the role of topology in field theory (Wu) have uncovered some important new phenomena that straddle the boundary between condensed matter physics and elementary particle physics: fractional statistics (systems that are neither bosonic or fermionic), the quantum Hall effect, Berry's phase (manifested by observable Aharanov-Bohm effects that arise purely from the geometric structure of certain Hamiltonians), Chern-Simons gauge theory and its relationship to string theory, and on the time variation of the gravitational constant that naturally arises in superstring theories. Topological aspects of physical phenomena and the geometric and algebraic structures of physical laws are among Wu's principal interests. The search for a deeper synthesis of the fundamental forces of nature may very well depend on such mathematical insights.
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Theoretical Condensed Matter Physics

Research topics of the condensed matter theory group cover essentially all problems of current interest: transport and optical properties of disordered interacting electron systems, 2-D electron gas with spin-orbit interactions, physics of graphene, the integer and fractional quantum Hall effect, correlated electron systems, quantum phase transitions and various frustrated spin models. Transport properties of strongly correlated systems subject to various external perturbations are also being investigated.
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