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The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

Abstract: Modern metrology involves a tight integration of sensors with computation. Suppose that a quantum computer were inserted into this pipeline as the first step in receiving and transforming sensor signals, before classical processing. What could be accomplished?  I illustrate the possibilities with three scenarios for which quantum computation may enhance sensing: demodulation of phase shift keyed signals, trajectory discrimination, and RF signal detection. This is made possible by utilizing new capabilities provided by quantum error correction and quantum signal processing.

Host: Ana Maria Rey

Abstract: CryoEM and cryoET enable imaging of biological specimens frozen in vitreous ice, revealing 3D molecular or cellular structures at high resolution and in their native state. However, cryoET is limited by the “missing-wedge” problem due to restricted tilt angles, and cryoEM often suffers from preferred orientation, resulting in uneven sampling of angular views and leaving parts of Fourier space poorly covered. We developed IsoNet and spIsoNet to address these inverse problems through data-driven, self-supervised deep learning: both methods learn from collected data alone, using well-sampled orientations to infer under-represented ones. IsoNet restores isotropy in tomograms by reconstructing missing information; spIsoNet adapts these principles to single-particle and subtomogram averaging workflows, improving angular coverage and alignment. Together, our deep learning methods reliably mitigate previously challenging physical constraints in cryoEM/cryoET.

Abstract: The development of pulsed Electron Spin Resonance (ESR) spectroscopy at microwave frequencies above 100 GHz remains a challenging and costly task, primarily due to the limited output power of modern high-frequency solid-state electronics. Nonetheless, a range of critical scientific problems—such as dynamic nuclear polarization (DNP) enhancement of NMR and quantum computing applications involving electron spins—necessitate spin relaxation measurements at THz frequencies.

Text Box:An alternative to pulsed ESR that circumvents the need for high microwave power is rapid scan ESR, which still enables the extraction of spin relaxation times. This method involves fast sweeps of the excitation microwave frequency across the ESR line. When the sweep rate exceeds a certain threshold, characteristic oscillations—often referred to as "wiggles"—emerge in the ESR spectrum [1–3]. As demonstrated by Josef Dadok in NMR [4], it is possible to recover the undistorted, slow-scan spectrum through Fourier Transform analysis.

Importantly, these oscillations also encode valuable information about the electron spin–spin relaxation time (T₂), which can be extracted by fitting the rapid scan spectrum using modified Bloch equations. This approach enables measurement of spin–spin relaxation times on the nanosecond scale.

Moreover, the specific design of modern high-frequency ESR spectrometers supports multifrequency operation, allowing spin relaxation measurements across an exceptionally broad range of magnetic fields—all using a single spectrometer.

Finally, we will outline the future steps required to establish THz rapid scan ESR as a convenient, accessible tool for a wide range of scientific fields—from quantum information science to clinical diagnostics.

Abstract: Magnetism is the posterchild of how the interplay between electron-electron interactions and quantum physics promotes novel macroscopic phenomena. Historically, the evolution of our understanding of magnetism has been related to the discovery of new paradigms in condensed-matter physics, as exemplified by the connections between antiferromagnetism and Mott insulators, spin glasses and non-ergodic states, and spin liquids and fractionalized excitations. Recently, a new framework proposed to classify magnetic phases brought renewed interest in unconventional magnetic states, which are qualitatively distinct from ferromagnets and standard Néel antiferromagnets. Among those, altermagnetic phases have been met with enthusiasm by the scientific community, as they display properties found in both ferromagnets (like the splitting of electronic bands with opposite spins) and conventional antiferromagnets (like the absence of a net magnetization). Formally, what distinguishes these three different magnetic states are the crystalline symmetries that, when combined with time reversal, leave the system invariant. In the case of altermagnets, because these symmetries involve rotations, the system is endowed with unique properties such as nodal spin-splitting and piezomagnetism. In this talk, I will introduce the concept of altermagnetism and discuss its connection to long-standing problems in the field of quantum materials, such as multipolar magnetism and electronic liquid-crystalline phases. I will also present the predicted experimental signatures of altermagnetic order in thermodynamic and transport properties, and show that altermagnets provide a fertile ground to realize non-trivial topological and superconducting phenomena in quantum materials.

Abstract: Polaritons are hybrid light-matter states with unusual properties that arise from strong interactions between a molecular ensemble and the confined electromagnetic field of an optical cavity. Cavity-coupled molecules appear to demonstrate energetics, reactivity, and photophysics distinct from their free-space counterparts, but the mechanisms and scope of these phenomena remain open questions. I will discuss new experimental platforms that the Weichman Lab is developing to investigate molecular reaction dynamics under strong cavity coupling.

While polaritons are now well-established in solution-phase and solid-state systems, they had not been previously reported in isolated gas-phase molecules, where attaining sufficiently strong light-matter interactions is a challenge. We access the strong coupling regime in an intracavity cryogenic buffer gas cell optimized for the preparation of simultaneously cold and dense ensembles and report a proof-of-principle demonstration in gas-phase methane. We strongly cavity-couple individual rovibrational transitions and probe a range of coupling strengths and detunings. In ongoing work, we are harnessing this infrastructure as a testbed for fundamental studies of polariton physics and chemistry.

We are also searching for signatures of cavity-altered dynamics in benchmark solution-phase systems. So far, we have focused on radical hydrogen-abstraction processes, which have well-characterized reactive surfaces and can be initiated with photolysis and tracked directly on ultrafast timescales. We use ultrafast transient absorption to examine intracavity reaction rates with the goal of better understanding exactly how and when reactive trajectories may be influenced by strong light-matter interactions.

Parker Solar Probe successfully completed its prime mission in 2025, measuring solar wind plasma in-situ as close as 8.8 solar radii (~0.04 AU) from the solar photosphere over a series of close-approach orbits. These close approaches to the Sun enable novel exploration of fundamental stellar processes, such as solar wind acceleration, solar wind heating, interplanetary dust destruction, and radial evolution of solar surface structure. These processes leave distinct signatures in near-Sun particle and field observations that allow us to untangle the physical mechanisms driving them. Further, travel through the extreme near-Sun environment has revealed a new regime of strong interactions between a spacecraft and its plasma environment. Insights gained from exploring the physics of these interactions have directly led to novel measurement capabilities on sounding rockets, small sats, lunar landers, and flagship space science missions. This talk focuses on advances in solar wind physics made over the course of the Parker Solar Probe mission, as well as on new space plasma measurement capabilities inspired by these studies.

Please join us for a JAGS Industry Spotlight Seminar featuring Micron. A networking session with the speaker will take place at 12:30pm followed by a technical presentation about the ongoing projects. 

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

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The Department of Physics at the University of Colorado Boulder in collaboration with CUbit and JILA is hosting the third annual Physics and Quantum Career & Internship Fair on Friday, October 17^th from 12:00 - 3:00 p.m. in the Glenn Miller Ballroom.

This event will feature employers across all areas of theoretical, experimental, and computational physics. The fair will connect physics undergraduate and graduate students and recent alumni with laboratory and industry leaders to learn about internships and employment opportunities.

Sign up online

Handshake is CU's online recruiting tool used by thousands of employers. It is recommended, but not required for students to sign up for the 2025 Physics and Quantum Career Fair on Handshake.

Abstract: Non-methane volatile organic compounds (NMVOC) are emitted into the Earth’s atmosphere by varied biogenic and anthropogenic sources. Though the concentrations of these compounds are minute, they exert an outsized influence on atmospheric composition, primarily through their oxidation chemistry. This chemistry leads to the formation of key secondary species including tropospheric ozone, a harmful pollutant, and secondary organic aerosol (SOA), a key component of atmospheric particulate matter with implications for climate and air quality. Oxidation chemistry is a dense web of interconnected reactions. The branch points in this web are reactive intermediates: short-lived, open-shell species that often have several chemical removal pathways available to them. Peroxy radicals, RO2, formed from the reaction of alkyl radicals and molecular oxygen, are key intermediates in the atmospheric oxidation process. In the atmosphere, RO2 generally have 4 pathways available to them: 1) reaction with NO, 2) reaction with HO2, 3) isomerization, and 4) self- or cross-reactions. The relative importance of these pathways is often determinative of the ultimate outcomes of oxidation chemistry, affecting the extent to which oxidation results in the formation of secondary species, including ozone and SOA. Our group uses a variety of model-informed experimental approaches to investigate the fates of atmospheric peroxy radicals and their impacts on atmospheric composition. In this talk, I will focus on a series of recent, unconventional environmental chamber experiments designed to probe the product distributions that arise from isomerizations and self- or cross-reactions or single isomers of RO2.  These pathways remain uncertain, and have only recently been appreciated as important in the formation of secondary organic aerosol. Studying these pathways has proven challenging in traditional environmental chamber experiments due to coupling of oxidant generation with generation of HO2 or NO. To circumvent this, we use direct photolytic approaches to the generation of RO2. Here, an organic precursor with a photolabile functional group is introduced into an environmental chamber and photolyzed under UV lamps, yielding a single-isomer alkyl radical, which then reacts with O2 to form RO2. This simplifies downstream chemistry, and removes the need for an oxidant, giving greater control over experimental conditions and allowing for experiments where pathways 3 and 4 are the dominant fates of RO2. In parallel, we use a modified version of the Framework for 0D Atmospheric Modeling (F0AM) to select experimental conditions, tuning competition between different RO2 fates. By examining product distributions and kinetics, we examine the role of reactivity conditions and RO2 structure in determining RO2 fate and its impacts on downstream product formation and atmospheric composition. Further, I will discuss several computationally-informed environmental chamber experiments that are focused on finding so-called “uncanonical” reactions of RO­2, that is, reactions that involve molecular processes not typically considered for simple RO2 radicals. Using automated reaction mechanism generation, we identify several novel reactions of functionalized RO2. We perform carefully designed environmental chamber experiments with the goal of identifying products that are signatures of these unconventional pathways. The results are highly suggestive of these previously unexplored pathways, but also illustrate the extent to which a mechanistic understanding of atmospheric oxidation remains incomplete, motivating future work in this area.

The corona is a layer of hot plasma that surrounds the Sun, traces out its complex magnetic field, and ultimately expands into interplanetary space as the supersonic solar wind. This complex and unpredictable system varies over many orders of magnitude in space and time, so it's not surprising that we still do not have a complete theoretical understanding of its origins. In this talk, I will present some new observations and theoretical concepts that are helping us get closer to finally identifying and characterizing the physical processes responsible for the corona and solar wind. This will involve data from ground-based telescopes such as DKIST, space telescopes that observe in UV and X-ray wavelengths, and interplanetary probes such as Solar Orbiter and Parker Solar Probe. The theoretical concepts involve waves, turbulent eddies, and their evolution together with particles in collisionless plasmas. I hope to also discuss how this work feeds into the practical world of "space weather forecasting" and how it is being extended to better understand the high-energy activity and dynamic outflows of other stars. There are many lessons to be learned from the decades of advancements that came before us, and I will highlight some insightful work from my own mentors. Also, I am excited to talk about the great work being done on these topics by CU Boulder students. Lastly, I will conclude with future plans, including a brief review of new instruments over the next decade that will help us test (i.e., conclusively validate or falsify) our fanciful theoretical ideas.

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Control of spin and valley polarizations opens opportunities for spintronic and quantum information applications. Monolayer transition-metal dichalcogenides (TMDs) offer an appealing platform to harness such polarizations. TMDs host excitons in valley-shaped regions of their band structure, featuring well-defined carrier spins and obeying chiral optical selection rules. However, the technological potential of excitons in TMDs is impeded by rapid spin–valley relaxation.

I will present our theoretical/computational efforts to address and enhance spin–valley polarizations in TMDs through strong coupling to photons. Recognizing that chiral light is a manifestation of photonic spin, I will show such strong coupling to allow for efficient spin transduction through the formation of "chiral polaritons". I will furthermore show how a breaking of chiral symmetry in optical cavities allows valley–spin relaxation to be suppressed in embedded TMDs.

I will also discuss our efforts to unravel how spin–valley relaxation in TMDs is driven by lattice phonons. Towards this goal, my group has advanced nonadiabatic methodologies that allow delocalized phonon modes and topological effects to be incorporated within a mixed quantum–classical framework. Results for TMDs indicate this approach to enable the modeling of solid-state phonon-driven processes at realistic dimensionalities.

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The Hubble Space Telescope story has been a fascinating study in public policy, engineering, ethics, and science. The Hubble is perhaps the most productive scientific instrument ever created by humans. In May 2009, a team of astronauts flew to the Hubble Space Telescope on space shuttle Atlantis. On their 13-day mission and over the course of 5 spacewalks they completed an extreme makeover of the orbiting observatory. They installed the Wide Field Camera-3, the CU/Boulder Cosmic Origins Spectrograph, repaired the Advanced Camera for Surveys and the Space Telescope Imaging Spectrograph, as well as a number of maintenance activities. These Hubble spacewalks are considered the most challenging and complex efforts ever of people working in space. Now, 16 years later the Hubble is still going strong. Building on the servicing heritage of Hubble the Habitable Worlds Observatory is in the initial planning stages and promises to be a worthy successor to Hubble. As part of the design the Habitable Worlds Observatory will be serviceable, albeit by robotic means. The adventures of Hubble servicing and the future servicing of Habitable Worlds will be presented in this talk.

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Mid-Infrared (MIR) light can interact with molecules by selectively exciting molecular vibrational modes. In combination with photonic structures, MIR can target specific vibrational states of molecular to influence chemical reactions. In this talk, I will explain how photonic environments can modify molecular dynamics through strong light-matter coupling. This strong coupling leads to the molecular vibrational polaritons – a hybrid quasiparticle between light and matter. Using two-dimensional infrared (2D IR) spectroscopy, we have demonstrated that strong coupling to photonic environments can efficiently promote energy transfer within or between molecules, subsequently slowing down competing reaction pathways. We further explored the criteria to fulfill polariton-enabled energy transfer, by which we discovered and verified a new principle to enable intermolecular energy transfer through polaritons in disorder materials. Lastly, we employed a polariton propagation experiment to determine the number of active polariton states versus the inactive dark states. This research progress provide insights into a rational mechanism and designing photonic structures to modify chemical landscapes and influence reaction pathways.

The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

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The Department of Biochemistry invites professors and scientists from other universities and institutes to present seminars at the University of Colorado Boulder throughout the academic year. These seminars provide an opportunity for faculty and students to learn about exciting current research.

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