Research Areas

Research Areas

The Department of Physics at Lehigh has concentrated its research activities within several fields of physics listed below.

Research opportunities for students: Research projects are available for undergraduate and graduate students in each area listed below. Undergraduate students can do research for credit by signing up for PHY 273. Research topics are arranged informally as early as the sophomore (or occasionally freshman) year at the initiation of the student or formally as a senior research project. Research projects in most of the following areas are also available to applicants to the Lehigh Physics Research Experiences for Undergraduates (REU) program, supported in part by the National Science Foundation. Graduate students complete a small research project (Physics 491) during the summer following their second semester, and then undertake a larger research project when working towards their PhD degree.

Astronomy and Astrophysics

Current research involves theoretical and observational studies of stars and planets, with areas of particular interest being stellar astrophysics, the discovery and characterization of exoplanets, and the search for extraterrestrial life.
Observational: Investigating the formation of disks around Be stars; measuring the properties of Mira and other variable stars; fundamental properties of massive stars; ages, composition, and dynamics of young stellar clusters; interactions between stars and compact objects in high mass X-ray binaries and gamma-ray binaries (McSwain). Discovery of new exoplanets and variable stars; characterizing the properties of populations of variable stars; identifying rare eclipsing or pulsating objects (Pepper).
Theoretical: Modeling the atmospheres and internal structure of stars (McSwain). Design and optimization of astronomical surveys, specifically for exoplanets and stars (Pepper).

Atomic, Molecular, & Optical Physics Experiment

Current research investigates the physics of quantum many-body systems through studies of ultracold atomic gases and the physics of light-matter interaction in molecular and condensed matter systems. Experiments on superfluidity, spin and heat transport, and thermodynamics of strongly-interacting Fermi gases employ laser cooling and optical trapping to produce quantum degenerate atomic gases, and tailored optical potentials, radiofrequency spectroscopy and other techniques to perform measurements (Sommer). Thermalization and condensation of photons is studied in dye media confined within a narrow optical cavity (Kim). Multi- photon interactions mediated by matter (nonlinear optics) are studied towards photonics applications such as all-optical switching and electro-optic modulation (Biaggio) and several optical tools are used and developed for research in condensed matter physics (Biaggio, Dierolf, Toulouse).

Biophysics

Researchers in the physics department employ the tools of physics to study the organization and dynamics of biological systems. They are involved in interdisciplinary collaborations with researchers in biology, bioengineering and related fields.
Theory: Mathematical and computational studies of cell division, cell motion, polarized growth, and mating; physics of cytoskeletal self-organization. Statistical mechanics and soft matter physics applied to actin protein assemblies and their emergent collective properties. (Vavylonis).
Experiment: Application of optical imaging, trapping, and manipulation for cell mechanics studies (Ou-Yang). A combination of fluorescence microscopy, lipid physical chemistry, and fluid mechanics is used to investigate the mechanical principles underlying the response of living cells to fluid flow (Honerkamp-Smith).

Computational Physics

Many of the fields of physics research at Lehigh involve the use of state-of-the-art computers to address large-scale computational problems. Researchers in the physics department employ diverse computational approaches to model complex many-body systems in condensed matter and quantum systems, the role of defects in strongly correlated systems, quantum criticality and non-Fermi liquid behavior (Ekuma); the detection of variable signals in large astronomical surveys (Pepper); coarse-grained models of biological systems with molecular dynamics, statistical, and continuum methods (Vavylonis); large- scale data analysis in high energy and nuclear physics (Reed). Development of reinforcement-learning-based atomic force microscopy (Dierolf). The computational research is performed at both high performance computing facilities on campus and in national facilities.

Condensed Matter Physics

Research in the Physics Department covers a wide area of topics in condensed matter systems.
Experiment: Activities span from molecular materials organic and inorganic semiconductors, wide bandgap semiconductors, point defects, rare earth doping, and ferroelectrics. Exciton dynamics in molecular crystals and organic semiconductors, including singlet exciton fission and triplet exciton fusion, is studied via pump and probe spectroscopy and fluorescence dynamics (Biaggio). Other techniques include nonlinear optical spectroscopy (Biaggio) and infrared optical spectroscopy under application of hydrostatic pressure, and magnetic fields (Stavola). Point defects in insulating materials with ferroelectric domain walls and other dopants; excitation processes of rare earth in wide band gap semiconductors, formation dynamics of single crystals in glass (Dierolf). For Defects in semiconductors, current interest is in defect complexes that contain light- element impurities such as H, C, O, and N, where vibrational spectroscopy and uniaxial stress techniques are used to elucidate microscopic properties (Stavola, Fowler). Other topics include Raman and neutron scattering, dielectric and ultrasonic spectroscopies, collective vibrational dynamics of disordered ferroelectrics and glasses (Toulouse).
Theory: Novel two-dimensional layered materials and their hybrids, heterostructures, and interfaces; Electronic and related properties of bulk semiconductors and insulators; Impurities and defects in materials including their interplay in strongly correlated materials/systems; The physics of carrier localization in model systems and real materials (Ekuma). Topological condensed matter physics, superconductivity, classical and quantum phase transition in strongly correlated and disordered systems, and field theory (Roy).

High Energy Nuclear/Particle Experiment

Current research involves the study of relativistic heavy-ion collisions at the Solenoidal Tracker at RHIC (STAR) and sPHENIX experiments at the Relativistic Heavy Ion Collider (RHIC). This field of research focuses on the study of matter under extreme conditions of temperature, density, and pressure, where the quarks and gluons that make up normal nuclear matter are no longer confined into hadrons. This deconfined matter is called the quark gluon plasma (QGP), and experiments use high-energy probes, such as particle jets and heavy flavor quarks, to determine how quarks and gluons lose energy in this medium (Reed).

High Energy Theory and Cosmology

String theory, quantum field theory and cosmology. Areas of interest include the connection between gravitational theories and quantum field theories, holographic gauge/gravity dualities, the behavior of strongly correlated quantum phases of matter, purely mathematical aspects of string theory as well as the study of inflation and dark energy in supergravity and string theory (Cremonini, Wrase).

Nonlinear Optics and Photonics Experiment

Research topics include nonlinear optical techniques for the study of higher orders of light-matter interaction that enable the coupling of electronic and photonics and the control of light with light, and the development of new organic materials for photonics and optoelectronics applications such as all-optical switching and electro-optic modulators (Biaggio). Other activities include optical frequency conversion, and nonlinear optical effects in fibers and waveguides (Biaggio, Dierolf, Toulouse).

Plasma Physics Experiment

Collisional and collisionless phenomena of very dense plasmas in or near a local thermodynamic equilibrium; radiation transport and lowering of ionization potentials in dense plasmas; nanocrystallites in plasma flow (Kim).

Soft Condensed Matter Physics and Complex Fluids

Biopolymer networks, biomembranes, and colloidal suspensions are investigated using experimental techniques such as confocal microscopy, laser tweezers, electro-osmotic control, microfluidics, in combination with image analysis and computational modeling.
Research areas include phase separation on cell membranes (Honerkamp-Smith); microrheology of macromolecules and living cells, generalized sedimentation equilibrium of colloidal suspensions, active colloidal suspensions far from equilibrium, diffusion in complex and/or crowded environments, light scattering, and formation and evolution of nanoscale complexes in solutions (Ou-Yang); modeling and image analysis of biopolymer and cytoskeletal networks (Vavylonis); nonlinear dynamics in fluid systems (Kim).

Statistical & Thermal Physics

Experiment: Intrinsic fluctuations in fluids under external forcing; light scattering from fractals; 1/f-dynamics of granular avalanches (Kim).
Theory: Disorder and transport in metallic alloys; nanocrystallite formation at near melting point; network theory modeling of entropy production (Kim).

Physics Education

Specific content-oriented instructional improvements. General investigation of student experience and performance via quantitative and qualitative analysis (Licini).