The UChicago Pritzker School of Molecular Engineering was well-represented as physicists from around the world gathered to celebrate the American Physical Society’s 125th anniversary.
The APS March Meeting 2024, held earlier this month in Minneapolis, was a scientific research conference convening 13,000 physicists and students from around the world to connect and collaborate across academia, industry and major labs.
The highlights included:
- 7 presentations from Pritzker Molecular Engineering faculty
- 20 presentations from University of Chicago faculty
- 14 UChicago departments represented
- The inaugural PME Industry Networking Night
PME presentation highlights
Multiconfiguration Pair-Density Functional Theory for Strongly Correlated Systems
Laura Gagliardi, Richard and Kathy Leventhal Professor in the Department of Chemistry, the Pritzker School of Molecular Engineering, and the James Franck Institute. Director of the Chicago Center for Theoretical Chemistry.
An overview of recent developments in multiconfiguration pair-density functional theory (MC-PDFT) will be presented, with special emphasis on linearized PDFT (L-PDFT).[1] The method involves the construction of an effective L-PDFT Hamiltonian operator, achieved by expanding the MC-PDFT energy expression to first-order in a Taylor series of the wave function density. This approach allows for the accurate prediction of potential energy surface topologies near conical intersections and locally avoided crossings, even in challenging cases like phenol, methylamine, and the spiro cation. Additionally, we will introduce quantum embedding and localization methods tailored to characterize systems ranging from extended, strongly correlated molecules to periodic systems. We will present the integration of quantum embedding with MC-PDFT, utilizing densities derived from periodic density matrix embedding theory.[2] Our discussion will feature examples of calculations related to local excitations within both solid-state materials and molecules.
Juan de Pablo, Liew Family Professor of Molecular Engineering
Hidden time-reversal symmetry and exact solutions of driven-dissipative spin models
Aashish Clerk, Professor of Molecular Engineering
Quantum systems subject to both driving and dissipation often have complex non-thermal steady states, and are at the forefront of research in many areas of physics. I’ll discuss how a subtle kind of anti-unitary symmetry (what we term "hidden time-reversal symmetry") can enable exact solutions of several non-trivial many-body models (described by Lindblad master equations) in regimes where conventional approximations fail. The focus will be on a driven-dissipative transverse field Ising model, which describes a collection of Rabi-driven qubits interacting via long range Ising interactions, and subject to loss (both single qubit and collective). Our solution reveals a wealth of phenomenon, from the emergence of phase transitions as the number of qubits grow, to disorder effects associated with inhomogeneous driving [1]. This system could be directly realized in a number of different platforms, including trapped ion quantum simulators and superconducting circuits. I will also discuss the application of our method to other driven-dissipative many-body models, including boundary-driven spin chains [2] and driven photonic systems.
Electronic structure and coherent states of spin defects in solids and molecules
Giulia Galli, Liew Family Professor of Molecular Engineering
In this talk, I will describe theoretical and computational strategies based on quantum mechanical calculations, aimed at predicting the electronic structure and coherent states of spin defects in two- and three-dimensional semiconductors and insulators and in molecular complexes. I will present results obtained on both classical and near-term quantum computers and discuss the use of spin defects as qubits and their application for quantum sensing and communication technologies.
Biomimetic Designs for Semiconducting and Light-Emitting Polymer
Sihong Wang, Assistant Professor of Molecular Engineering
The vast amount of biological mysteries and biomedical challenges faced by humans provide a prominent drive for seamlessly merging electronics with biological living systems (e.g. human bodies) to achieve long-term stable functions. Towards this trend, one of the key requirements for electronics is to possess biomimetic form factors in various aspects for achieving long-term biocompatibility. To enable such paradigm-shifting requirements, polymer-based electronics are uniquely promising for combining advanced electronic functionalities with biomimetic properties. In this talk, I will introduce our new molecular design and chemical synthesis concepts for semiconducting and light-emitting polymers, which enabled the incorporation of various biomimetic properties, such as stretchability, bioadhesive properties, tissue-like softness, and immune-compatible properties. First, I will discuss our new polymer design concepts in incorporating stretchable, tissue-adhesive, and biocompatible properties onto semiconducting polymers with redox-active properties, which can be used for biosensing and neuromorphic computing. Next, I will show our design of stretchable light-emitting polymers with high quantum efficiency, which is enabled by the use of thermally activated delayed fluorescence. Collectively, our research is opening up a new generation of electronics that fundamentally changes the way that humans interact with electronics.
Exploring the Application of Electrochemical Stimulus to Dynamic Disulfide Based Polymers
Shrayesh Patel, Assistant Professor of Molecular Engineering
Dynamic polymers incorporating disulfide bonds have been studied on account of the wide range of available stimuli that can be used to break the bond and induced dynamic bond exchange, such as heat, light, and base. However, the application of voltage as an electrochemical stimulus has been largely unexplored. Here, this talk will focus on how we are leveraging the electrochemical properties of disulfide-based polymer particles to demonstrate unique adaptive functionality. Specifically we have synthesized poly(glycidyl methacrylate) microparticles crosslinked with redox-responsive bis(5-amino-l,3,4-thiadiazol-2-yl) disulfide moieties (DS) to yield redox active particles (DS-RAPs). The resulting DS-RAPs show improved electrochemical reversibility compared to a small molecule disulfide analogue in solution, attributed to spatial confinement of the polymer-grafted disulfides in the particle. Moreover, by taking advantage of the electrochemical stimulus response, we have shown DS-RAPs particles can be cleaned from a fouled electrode surface under reductive potential and convective fluid flow, and thus introducing an innovative particle design strategy with intrinsic cleaning functionality. Lastly, the electrochemical stimulus-response and the resulting controlled electrolyte swelling has opened up a new pathway for responsive colloidal particles in solution. Overall, the novelty of this work focuses on the application electrochemical stimulus to drive the redox reactivity and dynamic nature of the DS-RAPs to enable unique functionality.
Electrochemically Active Metasurfaces
Po-Chun Hsu, Assistant Professor of Molecular Engineering
Electrochemistry is a powerful tuning knob for inducing drastic material property change. By applying an electrical bias while using counterions to maintain charge neutrality, electrochemistry can vary the carrier density or even trigger a phase transformation in an electrically addressable manner. Electrochemistry is an ideal tool in many applications where tunable range, scalability, or non-volatility is crucial. However, electrochemically active metasurfaces are still largely underexplored, probably due to the lack of a property database to perform metasurface design and optimization. More co-development is needed among fundamental materials science, metasurface design, and electrochemical device engineering. In this talk, I will present two examples of electrochemically active metasurfaces. (i) Conducting polymer near-perfect dynamic thermal emitter. We conducted infrared ellipsometry to measure the potential-dependent optical property and designed a tunable MIM near-perfect absorber for wearable variable emittance (WeaVE) devices for personal thermoregulation. (ii) Reversible metal electrodeposition for active beam steering metasurface. Because reversible electrodeposition can create and dissolve metals on demand, active metasurface can be achieved by creating and dissolving the meta-atoms or affecting the periodicity. As a proof of concept, we will demonstrate a reflection-type beam steering metasurface based on this principle and discuss the outlook and future challenges and opportunities.