# IU Summer REU Research Projects in the Department of Physics

Here are a few examples of potential REU research projects based in the

Department of Physics at Swain Hall West.

## Astrophysics

**Prof. ****Liese vanZee, Astronomy**

Measurement of the gas phase kinematic properties of nearby galaxies enables studies of both their gravitational potential and the connection between baryonic components (gas, stars, and dust) and dark matter halos. Students use the combination of observations of the neutral gas (from the 21cm spin-flip of neutral hydrogen) and observations of the ionized gas (from the Hydrogen Balmer-alpha line and the forbidden lines of [NII] and [SII]) to measure rotational velocities and local velocity dispersions. To measure the dark matter potential, students correct the observed rotation curve for inclination effects and decompose the rotation curve into baryonic and non-baryonic components. Students also analyze the velocity dispersion measurements to investigate whether the ionized gas is gravitationally bound to the system. These measurements provide insight into the physical conditions and evolutions of the interstellar medium in galaxies.

## Atomic, Molecular, and Optical Physics

##### Experimental Quantum Information Processing

**Prof. ****Phil Richerme, Physics**

Individual atoms can be trapped, collected into arrays, and cooled to their quantum ground states to form a synthetic quantum material. These engineered quantum systems can be studied and reprogrammed in a well-controlled laboratory environment, allowing for investigations of quantum many-body systems that are inaccessible in real materials or through numeric simulations. Undergraduate students assist in the development of laser, optical, electronic, and vacuum systems needed to run the apparatus. In the past two years, Prof. Richerme has supervised one Summer REU student as well as ten IU undergraduates.

##### Engineering Long-Range Interactions Between Ultracold Atoms

**Prof. Brian Desalvo, Physics**

Using laser cooling and evaporative cooling, dilute gases of neutral atoms can reach extraordinarily low temperatures where quantum mechanics dominates their behavior. Although the conditions are extreme, these gases offer a simple and flexible system for quantum simulation as well as novel ways to store and manipulate quantum information. Different isotopes of the same atomic species offer the ability to create quantum degenerate gases with either bosonic or fermionic statistics, and by using laser light and magnetic fields one can tune the geometry, dimensionality, and even interparticle interactions of these gases at will. In the DeSalvo Lab, we explore these gases both in and out of equilibrium and seek to develop new methods to control long-ranged interactions between the atoms, ultimately allowing access to a rich variety of novel quantum phases.

## Biophysics

##### Neural Networks and Dynamical Systems

**Prof. John Beggs, Physics**

Cortical slices and cultures are prepared from rat and mouse brains. These simplified slice networks are placed on advanced microelectrode arrays, allowing up to hundreds of individual spiking neurons to be sampled at high temporal resolution. We borrow concepts from statistical physics (models of frustrated magnetic materials, models of avalanching systems, models of complex networks) to describe the activity we see in data sets recorded with the microelectrode arrays. Current projects on which undergraduates have worked include measuring information flow between neurons, modeling trajectories of network activity through a simplified state space, developing maximum entropy models to describe the probability distribution of network states, applying new measures of synergy between information flows to cellular automata models and to neurophysiological data.

##### Visual Information Processing

**Prof. Rob de Ruyter, Physics**

Vision in animals, including humans, is based on an ongoing interpretation of optical signals gathered by the eye, and the physical properties of these highly complex signals put fundamental limits on visual information processing. We study visually guided behavior in a specially developed flight tracker system. The fly uses adaptive computational strategies to cope with the complexity of the visual input data stream, and we try to understand these strategies on a quantitative basis, hoping to uncover fundamental principles of biological computation.

## Condensed Matter

##### Controlled Synthesis and Characterization of Nanostructured Topological Crystalline Insulators

**Prof. Shixiong Zhang**

Topological crystalline insulators (TCIs) are a novel class of quantum materials that have unique metallic states on their surfaces. Such materials are expected to have potential applications in several fields, including tunable electronics and spintronics. The REU students will perform bottom up synthesis of various types of TCI nanostructures and carry out nanoscale characterization of the physical properties. This project will provide students unique opportunities to participate in of condensed matter physics, materials science and nanotechnology.

##### Topological States of Matter

**Prof. Babak Seradjeh**

In the past decade, the theory and experimental promise of topologically ordered states has been greatly expanded beyond the paradigmatic quantum
Hall effect, leading to the discovery of several families of two- and three-dimentional topological insulators and candidate topological superconductors.
The electrons in these systems are inert in the bulk, yet cost vanishingly little energy to excite at the system boundaries or inside bulk defects.
These topological "zero modes" are typically governed by the Dirac equation, leading to some spectacular properties, such as half-integer charge fractionalization,
quantized magneto-electric effect, emergent magnetic monopoles, and nonlocal entanglement. The student in this project will investigate aspects of model
topological insulators and superconductors by employing analytical and simple numerical methods using Mathematica or Matlab, or coding in C/C++/Fortran.
The problems are designed to understand the fundamental principles governing the system, their connection to experiments, and potential applications and
architectures for novel devices. The student will become familiar with relevant experiments, will learn the underlying concepts and a selection of theoretical techniques,
including exact diagonalization, field theoretic, variational and perturbative methods.

## Elementary Particle Experiment

##### The NOvA Neutrino Oscillation Experiment

**Prof. Mark Messier, Physics**

NOvA studies the muon-to-electron neutrino oscillation using both neutrinos and anti-neutrinos. Students will help to develop and test event reconstruction software and use the standard tools of high energy physics to simulate detector performance, analyze events from the detector, and test ideas for improvements or enhancements to the existing detectors.

## Elementary Particle Theory

##### Dark Energy

**Prof. Mike Berger, Physics**

The introduction of an interaction for dark energy to the standard cosmology offers a potential solution to the cosmic coincidence problem, a scheme for introducing a holographic foundation for dark energy, as well as the possibility of giving a unified description of early inflation and present accelerated expansion of the Universe. Students perform analytical work as well as numerical simulations to investigate possible physical choices for the behavior of dark matter in the Friedmann-Robertson-Walker framework. The goal is to obtain a good fit to the observational data supporting an accelerating Universe, and a successful model would represent a possible alternative interpretation of the expansion history of the Universe.

##### Theoretical Studies of Relativity Tests

**Dr. Ralf Lehnert, Physics**

Special relativity (SR) is one of the most basic and best confirmed theories physics. However, recent theoretical ideas in the context of new models beyond established physics suggest that there may, in fact, be the possibility of small departures from SR. Such hypothetical deviations from SR would affect many physical systems, such as the relation between energy and momentum for free particles. Predictions of this type can be employed for ultra-sensitive experimental tests of SR. This project involves modeling such deviations from SR with the goal to identify possible high-precision relativity tests. The prerequisites for research along these lines include an elementary knowledge of SR and basic undergraduate electrodynamics and quantum mechanics.

# IU Summer REU Research Projects at the Center for Exploration of Energy and Matter/Nuclear Theory Center

Here are a few examples of potential REU research projects based at the

Indiana University Center for
Exploration of Energy and Matter.

## Low Energy Neutron Source (LENS)

##### Small Angle Neutron Scattering (SANS) Studies of Nanostructured Materials

**Prof. David Baxter, Physics and CEEM**

The presence of the LENS facility within the department offers a number of unique opportunities for undergraduate research on materials. Prof. Baxter has particular interest in the
SANS technique which probes the mesoscopic structure of materials (length scales from 1 to 100 nm), and in studying hydrogenous materials that may be suitable for improved neutron
moderators through neutron transmission experiments. With both techniques it is possible to introduce students to the fundamentals, collect data on several samples, and complete the
analysis of suitable samples within a period of 5 to 8 weeks. Specific projects we envision pursuing with students supported by this grant include neutron transmission of materials
that may be used in future very cold neutron (VCN). Publication of these data is eagerly anticipated by the VCN community as these data are needed for testing new simulation codes for
future source design. SANS projects of interest include geological samples (clays and coals), bone, and nanoparticles ranging from virus capside surrounding magnetic nanoparticles to
molecular-sized graphene sheets (produced by colleagues in Chemistry).

## Nuclear Physics and Nuclear Chemistry Experiment

##### Many Body Nuclear Dynamics

**Dr. Sylvie Hudan and Prof. Romualdo DeSouza, CEEM and Nuclear Chemistry**

Many body nuclear dynamics examines the nuclear equation of state and the interplay between the statistical and dynamical break-up of nuclei under
extreme conditions of density, temperature, shape, and isospin. Recent projects include Studying Nucleon Transport in Hot Nuclear Matter and Studying
Mid-Peripheral Heavy-Ion Collisions. Dr. Hudan has supervised three REU students in the past five years.

##### Exotic spin-dependent interactions

**Prof. Mike Snow, Physics and CEEM**

Prof. Snow has conducted a number of tabletop experiments to search for possible exotic spin-dependent interactions of nature that are predicted in certain string theories. This work concentrates on interactions with ranges between millimeters and microns. The small scale of these experiments makes it possible to involve students in the experiments at the hardware level, and students are able to complete a coherent project during the summer. Students design key instrument components using Inventor and test them in the labs at CEEM before they are deployed at national laboratories such as LANSCE, SNS, and the NIST reactor.

## Nuclear Physics Theory

##### Molecular dynamics simulations of neutron star crust

**Prof. Adam Szczepaniak, Physics and Nuclear Theory Center**

The student will study properties of quark-gluon interactions in Quantum Chromodynamics formulated as a many-body, Hamiltonian system with
physical degrees of freedom. The student will investigate the distribution of energy density in presence of quark and antiquark sources and
its connection with phenomenological models of hadrons. Professor Szczepaniak has supervised five REU students working on theoretical projects in the
past six years.

##### Molecular dynamics simulations of neutron star crust

**Prof. Chuck Horowitz, Physics and Nuclear Theory Center**

Neutron stars are extraordinarily dense objects more massive than the sun but only about 20 km across. They offer a unique laboratory for study of nuclear matter at varying densities. The student will perform and analyze the results of molecular dynamics simulations to determine properties of the star's solid outer layers.

Star crust 10 billion times stronger than steel.