Summer 2025 Research Project offerings are in the following areas of Physics:

• Elementary Particle Physics (2 projects)
• Condensed Matter Physics (2 projects)
• Physics of Soft Matter (1 project)
• Physics of Living Systems (Biophysics) (2 projects)
• Astronomy (2 projects)

Note that the areas of Soft Matter and Biophysics have significant crossover in research, so if you are interested in either area, look at all 3 projects listed under these areas.

RESEARCH PROJECTS

The MilliQan experiment: searching for fractionally charged particles at the Large Hadron Collider  (by Professor David Stuart,  Experimental Particle Physics)

Understanding the dark matter observed to dominate the mass of the universe is a key goal of particle physics and has led to models for a dark sector of new particles. Mixing between the photon and a dark sector photon would give dark sector particles a suppressed coupling to the photon which would manifest as fractionally charged particles. A new experiment, called MilliQan, is searching for production of particles at the LHC with charges down to a thousandth of the electron charge. The detector elements consist of large plastic scintillators with photo-multiplier tubes that are readout by waveform digitizers. The intern will be trained in the operation of the detector, carry out bench-tests with the detector components, and analyze data from the experiment's ongoing operation.

The Caratelli group (http://hep.ucsb.edu/people/dcaratelli/) studies the properties of neutrinos: an elementary particle that is both ubiquitous yet mysterious. The discovery that neutrinos have non-zero mass puts them at odds with the standard model of particle physics and makes them a powerful probe for new discoveries in particle physics. To study these particles, we rely on large detectors called Liquid Argon Time Projection Chambers (LArTPCs) that take high-resolution "photographs" of neutrino interactions with matter. Interpreting these images is a visual task which requires complex algorithms to understand the images we collect. Machine Learning has emerged as a powerful tool to achieve this task. In this project, we will attempt to develop a method to distinguish between particles in our detector by relying on the kinematics of their decay leveraging Graphical Neural Networks (GNNs). This represents a novel way to analyze LArTPC images, and if successful can lead to new methods for measuring neutrino interactions and searching for particles yet to be discovered. As part of this work, we will also try to make these networks robust to uncertainties in our simulation by mixing our data with known mis-modeled effects in our detector. During the internship, the REU student will become familiar with visualizing and interpreting LArTPC neutrino interaction images, learn how to use the software tools needed to train and evaluate GNNs, evaluate their performance, and study what features in the data are contributing to the network's results.

Investigating Novel Josephson Junctions  (by Professor Chris Palmstrom, Condensed Matter Physics / Materials) 

The study of novel materials and structures allows us to explore interesting physics and to form the basis for making new devices. A fundamental understanding of growth is critical to the advancement of materials and structures. In order to develop structures with novel properties, it is essential to control the interface structure and chemistry at the atomic level. The Palmstrom group has a strong emphasis on heteroepitaxial growth of dissimilar materials via molecular beam epitaxy (MBE). These include materials with different crystal structures, bonding, and electronic, magnetic, optical and topological properties. Recent efforts in the group have been to investigate novel Josephson Junctions, which are a critical component of superconducting qubits used in superconducting quantum computers. The proposed REU project is to investigate tunneling characteristics of superconductor/semiconductor/superconductor Josephson Junctions fabricated using a novel MBE growth system that enables the growth at cryogenic temperatures (<10K) to minimize interfacial reactions and compare properties of different superconductors, semiconductors and deposition conditions. The tunneling measurements will be made at temperatures down to ~50mK and the data analysis will involve fitting experimental data with models involving interfacial and bulk defects with the aim of correlating properties with growth conditions. This project is suitable for rising Juniors or rising Seniors.

Ultrafast imaging of spins in van der Waals materials (by Professor Chenhao Jin, Condensed Matter Physics) 

Condensed matter physics aims to understand how interactions between elementary particles give rise to the diverse properties of materials. Recently, van der Waals materials have become an exciting platform for this purpose as they can be thinned into single atomic layers and then stacked into artificial systems with unprecedented properties. One major challenge in their experimental investigation is on the technical side. While there are many power techniques to probe how charges distribute and move inside them, it is much harder to probe charge-neutral (quasi)particles such as spins. Jin lab develops new optical techniques to address this challenge in the most direct way – making movies of how spins move in space and time. This overarching goal involves diverse experimental and theoretical skills; and the intern’s specific project will depend on their interests and background. Natural starting point includes preparing van der Waals materials, building specific elements for the “movie recorder” (either hardware or software), analyzing the movies, etc.

Controlling liquid-liquid phase separation dynamics with active fluids (by Professor Zvonimir Dogic & Professor Cristina Marchetti,  Soft Matter Physics) 

Controlling soft interfaces is of fundamental interest and is also a key to creating diverse functional soft materials. Traditionally, interfacial control is accomplished through surface modifying agents, such as surfactants and block copolymers, which preferentially adsorb onto interfaces. The aim of this project is to explore an entirely different non-equilibrium mechanism for controlling and shaping soft interfaces. Specifically, we will use a microtubule-based active fluid that uses chemical energy from ATP hydrolysis to generate autonomous turbulent-like steady-state flows. We will merge this fluid with a passive phase separating system consisting of two immiscible polymeric solutions. We will explore how activity and autonomous turbulent flows influence the dynamics of phase separation. The focus of the project will be on characterizing the regime where active flows enhance the coarsening of smaller droplets with each other while simultaneously breaking up larger droplets, thus generating a non-equilibrium steady state consisting of finite-sized droplets. The REU student will learn sample preparation methods and will use optical microscopy to track and identify droplet fission and fusion events and thus quantify the process of phase separation. The student will also work closely with theoretician Cristina Marchetti to gain intuition on the physics behind these measurements and, if appropriate, will develop simple theoretical models that capture the essential physics.

Biophysical Aspects of Dynamics in Animal Gastrulation  (by Professor Sebastian Streichan, Physics of Living Systems / Biophysics)

Morphogenesis is the problem of how the genetic makeup encodes the form of embryos and organs. This is a dynamic problem at the interface of physics and biology. As quantitative biologists and physicists, we often seek to explain biological phenomena using previously understood physical principles. For example, during morphogenesis, cells flow along the surface of the embryo, much like a fluid. It is much less common that we explore how these same biological phenomena might enhance our understanding of less developed physics. One of the biggest obstacles for these explorations was the ability of scientists to manipulate the many complicated factors that determine developmental trajectories. Morphogen gradients, gene expression patterns, and geometric mechanical constraints each interact with one another to drive the ultimate shapes of growing tissues. It is only with recent advances in synthetic biological systems that we can begin to separate each of these factors and determine the important roles that they contribute to the growing organism.  The proposed project will use one of these synthetic systems, generated using explants from zebrafish embryos, to explore how two-dimensional boundary dynamics drives three-dimensional cellular flows. The undergraduate student will use explants placed on substrates of different geometries to explore how the topology of the surface changes the cellular kinematics of a developing organism. This project is suitable for students of all levels, and will expose them to emerging scientific concepts at the interface of physics and biology, advanced optics and microscopy concepts, and a rigorous quantitative approach to developmental biology phenomena.

Filming proteins in action (by Professor Mark Sherwin,  Experimental Condensed Matter Physics & Biophysics)

Proteins are ubiquitous biomolecular machines whose various functions facilitate life on earth. Static protein structures are well-understood via modern advancements in x-ray crystallography, (solid-state) nuclear magnetic resonance and most notably cryo-electron microscopy, as is evidenced by the 200,000+ protein structures logged in the Protein Data Bank (PDB) to date. Recently, the chemistry Nobel prize was awarded to AlphaFold, an artificial intelligence tool trained on PDB structures to predict protein conformations given an amino acid sequence. However, AlphaFold is currently not equipped to simulate protein function. To augment our existing protein archive and the power of our predictive tools, we need quantitative “movies” that capture distance changes between protein sites in real time and ideally in biologically relevant conditions. This task represents a principal frontier in structural biology.

In longstanding collaboration with Professor Songi Han’s group (Department of Chemistry and Biochemistry, now at Northwestern), the Sherwin Lab has developed a “camera” to “film” proteins in action. Our method involves using electron paramagnetic resonance spectroscopy at very high magnetic fields to obtain time-resolved spectra of triggered proteins with paramagnetic spin centers attached at cleverly chosen locations.

The project has seen early success and is at a stage where both exciting experiments and further innovations are at hand. In collaboration with local protein scientists Profs. Max Wilson (Molecular and Cellular Biology) and Arnab Mukherjee (Chemical Engineering), we have been able to perform and unpack experiments using our newest technique, “Rapid-Scan Time-Resolved Gadolinium Gadolinium Electron Paramagnetic Resonance” (TiGGER). In a simple proof of concept experiment illustrating how our technique can let us directly “see” an already accepted phenomenon, we observed Jα-helix unfolding upon blue light activation in a phototropin called AsLOV2. Now we are looking forward to probing still-standing mysteries regarding this domain, such as the possibility and characteristics of transient dimerization, and the functional role of light-induced regional disordering.

The summer curriculum for an interested REU student would involve the opportunity to independently design and perform rs-TiGGER experiments with AsLOV2 as well as a chance to grapple with the physics engineering side of the technological development process:

Learn foundational concepts in EPR and relevant biological background required to understand the rs-TiGGER technique and how we can use it to probe AsLOV2 dimerization during dark recovery. Shadow your grad mentor running experiments and learn how to operate rs-TiGGER independently. Design and execute your own experiment(s) to test the hypothesis that the Jα helix mechanically inhibits dimerization in the dark state by blocking β sheet association.

Perform literature review to understand the physics of Fabry-Perot resonators and how they can be used to indirectly increase time resolution by improving signal to noise ratio. Attempt to implement your own sample cell which exhibits Fabry-Perot interference (we will provide you some materials we think are a promising start). Along the way, you will likely learn both continuous wave and pulsed EPR modes and how to use the Vector Network Analyzer (VNA). If you succeed, you may open the door to observing transient biological phenomena that have never been directly measured before.