Colloquium Calendar

Title: "Exploring quantum simulation and entanglement dynamics of complex quantum systems with quantum computers"

Abstract: Quantum computers are opening new frontiers in fundamental physics, offering unprecedented opportunities to explore complex quantum systems. In this talk, I will present our recent quantum simulations focused on two key directions: (1) large-scale frustrated quantum spin chains and (2) black hole entanglement dynamics. Using IBM’s superconducting quantum computers, we successfully implemented a Heisenberg spin chain with competing nearest-neighbor and next-nearest neighbor interactions, achieving real-time evolution with up to 100 qubits and accurate expectation value measurements utilizing scalable constant-depth quantum circuits and error mitigation. I will also discuss our quantum simulation of black hole scrambling dynamics conducted with IBM's superconducting quantum computers. We employed randomized measurement and swap-based many-body interference protocols to investigate entanglement entropy dynamics, providing insights into the Page curve and the black hole information puzzle. Finally, our research showcases quantum computers as a nascent but powerful tool for exploring complex quantum systems and beyond.

Title: The Deep Underground Neutrino Experiment (DUNE): An International Experiment for Neutrino Science

Abstract: 

DUNE is a future experiment designed to answer two major open questions in neutrino science: What is the neutrino mass ordering (mass hierarchy); and do neutrinos violate CP invariance? In order to answer these questions, DUNE will measure neutrino oscillations over a long baseline utilizing the 1.2 – 2.4 MWatt wide-band neutrino beam from the Long-Baseline Neutrino Facility (LBNF) at Fermilab, a 40 kTon fiducial volume liquid argon time-projection chamber far detector located 1300 km from the beam source in the Sanford Underground Research Facility (SURF) in Lead, South Dakota, and a near detector system at the source. This talk will review recent results from neutrino oscillation measurements and present the design of DUNE along with its expected physics sensitivities. 

In addition to this summary, I will present details of two specific DUNE projects which Wichita State University is participating in: the design and analysis of the DUNE near detector system; and the development of core computing software, including a new data processing framework.

Title: Lagrange Communication Advanced Realtime Space-weather Array (LCARS): NASA Mission Concept

Abstract:: A Space-borne communication and sensor array outside of Earth’s orbit usable for Inner Solar System Communications (ISS Comms), Deep Space Network Communications (DSN Comms), and space weather is under study. We present updates of ongoing mission concept development for the Lagrange Communication Advanced Realtime Space-weather Array (LCARS)

LCARS Space Platforms would be placed at key solar system locations, autonomously warning Earth and protecting space assets.  Each LCARS Space Platform (LCARSSP) orbits the Earth-Sun Lagrange points:

• Surveillance of interplanetary medium and solar observations.
• Interplanetary and Heliospheric communications

The Lagrange point utility is shown from existing use as key location for the Space Weather monitoring and observational assets. For example, L1 hosts ACE, SOHO, WIND, DSCOVR, etc.; L2 hosts WIND, Planck, Gaia, JWST, Euclid, etc.; L4 hosted (STEREO A) and L5 hosted (STEREO B).

Each LCARSSP maintains relative position to Earth, allowing continuous monitoring of the sun and solar wind, the issuance of early warning alerts for terrestrial and space-based assets, and the collection of near 3D continuous data to aid in Earth-Sun space weather modeling.

The LCARS Array is also a Communications Infrastructure Mission that supports mission data transport through multi-bandwidth comms including radio, terahertz and laser for inter- LCARSSP and Lunar comms, and a gimbled deep space dish enhancing NASA’s DSN. The proposed array includes an autonomous inter- LCARSSP network for high bandwidth data flow throughout the solar system. 

We present detailed updates to our mission concept including timeline* for R&D and deployment by 2050. We focus on key technologies required during the next decade to support implementation, launch, and deployment by 2050.  These technologies span broad range of domains including comms systems, AI autonomation, modular spacecraft, self-assembly spacecraft, modular observational bays, retractable and variable shaped deep space reflector, etc.

Title: Tuning into Cosmic Neutrinos at High Elevation 

Abstract: Neutrinos are the ideal messenger for high-energy astrophysics. Weakly interacting and uncharged, they propagate undeterred and unabsorbed through the universe. In the last decade, the IceCube experiment has brought us the discovery of a flux of high-energy, TeV-scale neutrinos and through a multi-messenger lens — the combined observations of neutrinos and other messengers like photons —  we are starting to see hints of energetic neutrino sources for the first time. At higher energies still, beyond the PeV scale, we can probe the most energetic sources of both neutrinos and cosmic rays, but current neutrino experiments become too small to observe a sizable flux. Radio experiments can achieve the large exposures necessary by taking advantage of the coherent broadband radio emission resulting from ultra-high-energy (E>10^17 eV) neutrino interactions as well as the large volumes visible from high elevations. In this talk, I will review results from current and future high-elevation radio experiments, with a particular focus on Earth-skimming tau neutrinos and cosmic ray air showers as observed with from mountains and high-altitude balloons.

Title: Life After Physics 

Abstract:

What happens if you find yourself with an advanced degree in physics and you start to wonder if academia is not right for you? Is this normal? And what kind of jobs are out there for former physicists? In this talk I'll give some background on these questions, discuss my own journey from physics to software engineering, describe why a career in writing software might be right for you, and how to go about making the leap into a life after physics.

Title: Spin transport and spin-orbit torque in metallic heterostructures

Abstract: Current-induced spin-orbit torque enables electric control of magnetization in spintronic devices. I will start by discussing the basic phenomenology and mechanisms of spin-orbit torque. I will then discuss first-principles calculations of spin transport and spin-orbit torques in disordered films and multilayers using the nonequilibrium Green's function technique. Of particular interest is the generation of spin-orbit torque with unconventional spin polarization that can enable the switching of magnetization perpendicular to the film plane; this requires certain symmetries to be broken. I will discuss unconventional torques in ferromagnet/nonmagnet/ferromagnet trilayers, as well as spin currents generated by the so-called spin-splitting effect in altermagnets and anisotropic ferromagnets, which could be harnessed for this purpose.

Title: Exciton dressing by extreme nonlinear magnons in a layered semiconductor

Abstract: Collective excitations presenting nonlinear dynamics are fundamental phenomena with broad applications. A prime example is nonlinear optics, where diverse frequency mixing processes are central to communication, sensing, wavelength conversion, and attosecond physics. In this talk, I will present our recent results focused on the magnon behavior in the layered antiferromagnetic semiconductor CrSBr. I will demonstrate nonlinear opto-magnonic coupling to low order harmonics of the fundamental magnon. I will further show how we can create tunable optical sidebands from sum- and difference-frequency generation between two optically bright magnon modes under symmetry breaking magnetic fields. Moreover, the observed difference-frequency generation mode can be continuously tuned into resonance with one of the fundamental magnons, resulting in parametric amplification of magnons. Finally, I will show how we can access extreme high harmonic generation of the magnons by presenting exciton states dressed by up to 20 harmonics of magnons. These findings realize the modulation of the optical frequency exciton with the extreme nonlinearity of magnons at microwave frequencies, which could find applications in magnonics and hybrid quantum systems, and provide new avenues for implementing opto-magnonic devices.

Title: The Devil is in the (Axion) Details

Abstract: Over the last decade, one of the most popular solutions to the dark matter problem has been a hypothetical class of particles known as axions or axion-like particles. In this talk, I will discuss why the axion is such an attractive candidate and also explain the challenges we face in determining whether axions are the dark matter and which axion(s) are the dark matter. I will highlight results from my research group that indicates: the devil is in the details.

Title: The Roman survey for strong gravitational lenses amenable to millilensing characterization

Abstract:

Galaxy-galaxy strong gravitational lenses can constrain dark matter models and the Lambda Cold Dark Matter cosmological paradigm at sub-galactic scales. Currently, there is a dearth of images of these rare systems with high signal-to-noise and angular resolution. The Nancy Grace Roman Space Telescope, scheduled for launch in late 2026, will play a transformative role in strong lensing science with its planned wide-field surveys. With its remarkable 0.281 square degree field of view and diffraction-limited angular resolution of 0.11 arcsec, Roman is uniquely suited to characterizing dark matter substructure from a robust population of strong lenses. We present a yield simulation of detectable strong lenses in Roman's planned High Latitude Wide Area Survey (HLWAS). We simulate a population of galaxy-galaxy strong lenses across cosmic time with Cold Dark Matter subhalo populations, select those detectable in the HLWAS, and generate simulated images accounting for realistic Wide Field Instrument detector effects. For a fiducial case of single 146-second exposures, we predict around 93,000 detectable strong lenses in the HLWAS, of which about 500 will have sufficient signal-to-noise to be amenable to detailed substructure characterization. We investigate the effect of the variation of the point-spread function across Roman's field of view on detecting individual subhalos and the suppression of the subhalo mass function at low masses. Our simulation products are available to support strong lens science with Roman, such as training neural networks and validating dark matter substructure analysis pipelines.

Title: Manipulate topological phases and light-spin interactions in Rashba Materials

Abstract:

In this talk, I will present our two recent studies on manipulating the topological properties and light-spin interactions of Rashba materials. In the first part, I will introduce a type of artificial structure, the twisted type-II Rashba homobilayers, as a new platform for realizing topological moiré flat electronic bands. Using bismuth telluride iodide (BiTeI) as a material example, we demonstrate the formation of narrow flat bands and transitions from valley Hall to quantum spin Hall insulators with varying twist angles. The tunability in spin-orbit coupling, interlayer interactions, and twist angles expands the potential of Rashba materials for observing correlated topological phenomena. In the second study, I will discuss a novel second-order light-spin conversion mechanism via Rashba and cubic Dresselhaus spin-orbit couplings in ferroelectric Rashba semiconductors. Using first-principles simulations on α-phase germanium telluride (GeTe), we predict a photoinduced spin current that is significantly larger than the charge photocurrent and can be switched via an electric field. This approach offers light-driven and electrically tunable spin current for spintronic applications. 

Title: Momentum-Space Imaging of Electron and Exciton Dynamics in 2D Materials 

Abstract:

Our conceptual pictures and theoretical formulations regarding the dynamics of quasi-particles in crystalline materials, such as electrons, holes, and excitons, are formulated in momentum space. For example, when we think about how a semiconductor absorbs or emits light, we draw the band structure and arrows connecting the valence band and conduction band, along with scattering mechanisms characterized by energy and crystal momentum. However, our observables of these phenomena involve integrals over many states in momentum space, and are also blind to so-called “dark” states that do not interact with light. Significant interpretation is then required to connect optical spectra to the underlying momentum-space dynamics, and it is easy to get these interpretations wrong. 

Recently, breakthroughs in technology for time- and angle-resolved photoemission (tr-ARPES), developed at Stony Brook and a few other labs, make direct momentum-space snapshots of electron dynamics across the full Brillouin zone no longer just a theoretical construct but a recorded reality. In this talk, I will discuss both the optical science behind these recent breakthroughs in tr-ARPES and recent results from my lab. Specifically, I will discuss pseudo-spin dynamics in graphene, valley polarization dynamics in monolayer WS2, and the mixture of metastable exciton states produced in MoSe2/WS2 heterostructures after above-bandgap excitation. Direct visualization of momentum-space wave functions enables new discoveries unseen in previous measurements in each case, but this only represents a small glimpse of the science now accessible with these new techniques. Finally, I will present an outlook for some upcoming experiments and where the field is going with further advances in the techniques.

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