Summer 2024 Research Projects are in the following areas of Physics:

• Elementary Particle Physics
• Atomic, Molecular and Optical Physics
• Condensed Matter Physics
• Physics of Soft Matter
• Physics of Living Systems (Biophysics)
• Astronomy

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.

New Detector Technologies for Neutrino Physics (by Professor David Caratelli,  Experimental Particle Physics)

The Caratelli group (http://hep.ucsb.edu/people/dcaratelli/) focuses on experimental particle physics, with an emphasis on neutrino physics. The neutrino is a fundamental particle that is 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 fundamental physics. Furthermore, because neutrinos are produced in processes such as nuclear fusion, intense fluxes of neutrinos are emanated by many astrophysical sources including the Sun and Supernova bursts (the violent explosions of dying stars). This research project will involve hardware development for gas- and liquid-based argon Time Projection Chamber detectors which aim to measure faint signatures produced in neutrino interactions, as well as simulation aimed at optimizing detector design for future experiments.

Flexible Optical Potentials for Quantum Simulation with Ultracold Lithium, Strontium, and Potassium (by Professor David Weld, Atomic, Molecular and Optical Physics) 

The precision and control that can be attained in experiments on degenerate quantum gases have advanced to the point where cold atoms can be used to study many-body quantum phenomena relevant to other systems, most notably condensed matter.  This field, often called ``quantum simulation,’'  is especially well-suited to undergraduate involvement both because of the field’s fundamentally interdisciplinary nature and because the diverse experimental techniques lend themselves to modularity. The Weld group’s research in this field and in the area of quantum dynamics is based on three main experimental platforms: two large Bose condensate experiments based around lithium and strontium, and an optical-tweezer experiment using ultracold potassium. The undergraduate intern on this project will work with one or more of these degenerate quantum gas experiments.  The intern’s contributions will focus on the generation and control of optical potentials to enable new forms of dynamical quantum simulation. Specific project details will depend on the intern's interests and background. The optical, electronic, and software infrastructure which the intern will create will enable generation and optimization of shaped optical potentials for use in experiments exploring the response of quantum systems to nonadiabatic variations of the potential.

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.

High-field electron magnetic resonance spectroscopy (by Professor Mark Sherwin,  Experimental Condensed Matter Physics & Biophysics)

Electron magnetic resonance (EMR) spectroscopy can be used to probe the local environments of electron spins providing a unique and powerful window into structure and dynamics of condensed and biological matter. At UCSB, the Institute for Terahertz Science and Technology (ITST) led by Professor Sherwin currently hosts a unique capability of performing pulsed EMR spectroscopy at magnetic fields up to 12.5 Tesla (soon 16 Tesla) and frequencies of 240 GHz (soon 170-450 GHz), using as a source either a solid-state device or UCSB’s unique free-electron lasers. Current EMR activities are ideally suited for undergraduates with interests varying from instrument design to experimentation and data analysis. For example, an intern with relatively little experience might design, 3D print, and test an important component for the EMR spectrometer. An intern who knows Python or MatLab might work on new methods for analyzing large amounts of data accumulated as we “film” proteins in action using high-field electron paramagnetic resonance using our recently-developed capability to record complete EPR spectra of spin-labeled proteins every few ms. An intern who has completed quantum mechanics might apply this subject by doing measurements of high-field EMR spectra of quantum magnets, and analyzing these spectra using a program like EasySpin to extract parameters like g-anisotropy, which are important to reconstructing their effective spin Hamiltonians.

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.