Colloquia

Emily Gibson

CU Anschutz (Bioengineering)

CU Boulder, Physics

Studying Neural Circuits in the Brain Using Photonics

Understanding how the brain’s complex neural networks perform critical functions and govern behavior, cognition and intuition is a key goal of neuroscience and can lead to improved treatment for various neurological disorders. The development of new tools for studying the brain is critical in this effort. Light microscopy has greatly expanded the capabilities for minimally invasive cellular-level biological studies and in combination with genetically encoded fluorescent indicators allows unprecedented real-time imaging of neural activity. Although imaging in head fixed animals has greatly advanced the field of neuroscience, certain behaviors can only be studied in a freely moving animal in a naturalistic environment.  I will discuss our recent development of miniature head mounted microscopes to measure neural activity employing two-photon and structured illumination microscopy and combining optogenetic neuromodulation to probe neural circuits.

Emily Gibson

CU Anschutz (Bioengineering)

CU Boulder, Physics

Studying Neural Circuits in the Brain Using Photonics

Understanding how the brain’s complex neural networks perform critical functions and govern behavior, cognition and intuition is a key goal of neuroscience and can lead to improved treatment for various neurological disorders. The development of new tools for studying the brain is critical in this effort. Light microscopy has greatly expanded the capabilities for minimally invasive cellular-level biological studies and in combination with genetically encoded fluorescent indicators allows unprecedented real-time imaging of neural activity. Although imaging in head fixed animals has greatly advanced the field of neuroscience, certain behaviors can only be studied in a freely moving animal in a naturalistic environment.  I will discuss our recent development of miniature head mounted microscopes to measure neural activity employing two-photon and structured illumination microscopy and combining optogenetic neuromodulation to probe neural circuits.

Christina Willis

Sustainable Networking Workshop

Dr. Willis will be leading her 90-minute workshop on Sustainable Networking. If you are looking for a job , or will be soon, this is a “must” event for you!

Bio: Dr. Willis specializes in novel, high-power laser development and has worked in metrology; laser tracking and imaging; and LIDAR applications. She was selected to be the 2019–2020 Arthur H. Guenther Congressional Fellow, through which she served a year on a U.S. Senate committee in Washington, DC. She worked as a Legislative Aide for the 2021 session of the Colorado General Assembly and is now Director of External and Government Affairs at quantum technology company Infleqtion.

In her free time, she enjoys yoga, running, writing, and volunteering with a local fire department.

Christina Willis

Sustainable Networking Workshop

Dr. Willis will be leading her 90-minute workshop on Sustainable Networking. If you are looking for a job , or will be soon, this is a “must” event for you!

Bio: Dr. Willis specializes in novel, high-power laser development and has worked in metrology; laser tracking and imaging; and LIDAR applications. She was selected to be the 2019–2020 Arthur H. Guenther Congressional Fellow, through which she served a year on a U.S. Senate committee in Washington, DC. She worked as a Legislative Aide for the 2021 session of the Colorado General Assembly and is now Director of External and Government Affairs at quantum technology company Infleqtion.

In her free time, she enjoys yoga, running, writing, and volunteering with a local fire department.

Stephanie Wissel

Tuning into Cosmic Neutrinos at High Elevation 

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, both from balloon-borne instruments like PUEO and from mountaintop experiments like BEACON and HERON.

Stephanie Wissel

Tuning into Cosmic Neutrinos at High Elevation 

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, both from balloon-borne instruments like PUEO and from mountaintop experiments like BEACON and HERON.

Jeroen Audenaert

The NASA Transiting Exoplanet Survey Satellite (TESS): From Trillions of Data Points to Astrophysical Insights

The Transiting Exoplanet Survey Satellite (TESS) is an MIT-led NASA mission to discover transiting exoplanets, worlds beyond our solar system. Launched in 2018, TESS is now in its third extended mission, continuously observing millions of stars to search for subtle changes in brightness that can reveal everything from exoplanets and nearby asteroids to pulsating stars and supernovae.

The unprecedented volume of data from TESS opens new frontiers, but also poses a key challenge: how can we automatically and accurately analyze this vast, continuous stream of observations? In this colloquium, I will dive into the essential role machine learning and artificial intelligence play in this process, enabling everything from more accurate exoplanet detection models to building better instrument models, paving the way for an era of automated scientific discovery.

Jeroen Audenaert

The NASA Transiting Exoplanet Survey Satellite (TESS): From Trillions of Data Points to Astrophysical Insights

The Transiting Exoplanet Survey Satellite (TESS) is an MIT-led NASA mission to discover transiting exoplanets, worlds beyond our solar system. Launched in 2018, TESS is now in its third extended mission, continuously observing millions of stars to search for subtle changes in brightness that can reveal everything from exoplanets and nearby asteroids to pulsating stars and supernovae.

The unprecedented volume of data from TESS opens new frontiers, but also poses a key challenge: how can we automatically and accurately analyze this vast, continuous stream of observations? In this colloquium, I will dive into the essential role machine learning and artificial intelligence play in this process, enabling everything from more accurate exoplanet detection models to building better instrument models, paving the way for an era of automated scientific discovery.

We have 3 talks: 12 minute time slots: 10 minute talk, 2 minutes for questions.

We will have pizza & drinks available at Colloquium in CTLM 102 starting at 4 PM…

4:05 to 4:17 Calvin Bavor
4:18 to 4:30 Cameron Clarke
4:31 to 4:43 AJ Gray

4:44 to 4:50 – Pizza and clean up time !

Heather Lewandowski

Probing the Frontiers of Interstellar Chemistry Through Cold and Controlled Ion-Molecule Experiments

Ion-molecule reactions are fundamental to the chemistry that drives processes in the interstellar medium, but experimental measurements of these reactions are scarce due to significant technical challenges. We apply techniques from the field of cold atomic physics to examine ion-molecule reactions under well-controlled conditions that replicate the environment of space.

Our focus is on the reactions of small, carbon-based molecules. Benzene, an aromatic molecule, is widely considered a key precursor to larger polycyclic aromatic hydrocarbons (PAHs) in space. Despite benzene’s pivotal role in PAH formation, its formation mechanisms in the interstellar medium remain poorly understood. Scientists have suggested a pathway for interstellar benzene formation beginning with the protonation of acetylene, yet this reaction sequence has not been experimentally verified.

In our work, we present the first experimental study of sequential ion-molecule reactions initiated by acetylene protonation under single-collision conditions. Contrary to predictions, our results show that this reaction sequence does not produce benzene; instead, it terminates at the formation of C₆H₅⁺, a species unreactive to both acetylene and hydrogen. These results rule out a widely assumed pathway for interstellar benzene formation and place new constraints on the physical mechanisms underlying PAH growth in cold astrophysical environments.

Heather Lewandowski

Probing the Frontiers of Interstellar Chemistry Through Cold and Controlled Ion-Molecule Experiments

Ion-molecule reactions are fundamental to the chemistry that drives processes in the interstellar medium, but experimental measurements of these reactions are scarce due to significant technical challenges. We apply techniques from the field of cold atomic physics to examine ion-molecule reactions under well-controlled conditions that replicate the environment of space.

Our focus is on the reactions of small, carbon-based molecules. Benzene, an aromatic molecule, is widely considered a key precursor to larger polycyclic aromatic hydrocarbons (PAHs) in space. Despite benzene’s pivotal role in PAH formation, its formation mechanisms in the interstellar medium remain poorly understood. Scientists have suggested a pathway for interstellar benzene formation beginning with the protonation of acetylene, yet this reaction sequence has not been experimentally verified.

In our work, we present the first experimental study of sequential ion-molecule reactions initiated by acetylene protonation under single-collision conditions. Contrary to predictions, our results show that this reaction sequence does not produce benzene; instead, it terminates at the formation of C₆H₅⁺, a species unreactive to both acetylene and hydrogen. These results rule out a widely assumed pathway for interstellar benzene formation and place new constraints on the physical mechanisms underlying PAH growth in cold astrophysical environments.

Richard Mueller

Measuring the Neutrino Mass: Advancing Detector Design in Project 8

Abstract: Neutrinos occupy a unique role in the Standard Model of particle physics and have been the subject of intense study over the past century. The 1998 discovery of neutrino oscillations proved that these subatomic particles are massive; however, unlike other Standard Model leptons, the mechanism generating their mass remains unclear. This enduring mystery strongly motivates the search for new physics. In this talk, I will highlight recent research by the Project 8 neutrino mass experiment, which aims to measure the neutrino mass with a sensitivity of 40 meV/c^2—well below the current best limit. To achieve this, the collaboration is developing Cyclotron Radiation Emission Spectroscopy (CRES), a novel electron spectroscopy technique designed to resolve electron energies in tritium beta decay. Driven by the selection of large-scale microwave cavities as the primary detector technology, this presentation will focus on the detector’s electromagnetic design, its interaction with single electrons, and quantum signal enhancement strategies for future CRES experiments.

Richard Mueller

Measuring the Neutrino Mass: Advancing Detector Design in Project 8

Abstract: Neutrinos occupy a unique role in the Standard Model of particle physics and have been the subject of intense study over the past century. The 1998 discovery of neutrino oscillations proved that these subatomic particles are massive; however, unlike other Standard Model leptons, the mechanism generating their mass remains unclear. This enduring mystery strongly motivates the search for new physics. In this talk, I will highlight recent research by the Project 8 neutrino mass experiment, which aims to measure the neutrino mass with a sensitivity of 40 meV/c^2—well below the current best limit. To achieve this, the collaboration is developing Cyclotron Radiation Emission Spectroscopy (CRES), a novel electron spectroscopy technique designed to resolve electron energies in tritium beta decay. Driven by the selection of large-scale microwave cavities as the primary detector technology, this presentation will focus on the detector’s electromagnetic design, its interaction with single electrons, and quantum signal enhancement strategies for future CRES experiments.

Michael Wakin

All Aboard the Tensor Train: Structured Data Models for Signal Processing

Abstract: With the ever-growing complexity of signals and data comes the challenge—and the opportunity—of characterizing and exploiting latent structure. While many signals are traditionally modeled as vectors, viewing them as higher-dimensional matrix and tensor data structures has the potential to unlock hidden information and facilitate much more efficient processing.

This talk will survey low-rank and structured matrix/tensor models (such as Tensor Trains) that are increasingly valuable in modern signal processing and machine learning. I will discuss how these high-dimensional data structures are amenable to lower-dimensional parameterizations that reveal critical latent properties.

Highlighted applications will include matrix- and tensor-based initialization strategies for ultrafast laser pulse characterization (in collaboration with Jeff Squier) and Tensor Train models that facilitate efficient quantum state recovery from probabilistic measurements (in collaboration with Zhexuan Gong).

Michael Wakin

All Aboard the Tensor Train: Structured Data Models for Signal Processing

Abstract: With the ever-growing complexity of signals and data comes the challenge—and the opportunity—of characterizing and exploiting latent structure. While many signals are traditionally modeled as vectors, viewing them as higher-dimensional matrix and tensor data structures has the potential to unlock hidden information and facilitate much more efficient processing.

This talk will survey low-rank and structured matrix/tensor models (such as Tensor Trains) that are increasingly valuable in modern signal processing and machine learning. I will discuss how these high-dimensional data structures are amenable to lower-dimensional parameterizations that reveal critical latent properties.

Highlighted applications will include matrix- and tensor-based initialization strategies for ultrafast laser pulse characterization (in collaboration with Jeff Squier) and Tensor Train models that facilitate efficient quantum state recovery from probabilistic measurements (in collaboration with Zhexuan Gong).

Juliet Gopinath

Windows into places unseen: Optical fiber-based quantum sensing and super-resolution imaging

Abstract: I will discuss our advances in quantum fiber sensing, showcasing how distributed fiber sensing can provide new information with enhanced sensitivity in optical fiber. The advancements will enable measurements in difficult to reach environments such as the ocean or underground. Additionally, I will describe our fiber-coupled super-resolution microscope that enables a window into the brain. We use a bend-insensitive donut that can be transmitted through commercially available fiber along with a Gaussian excitation beam to demonstrate stimulated emission depletion microscopy. Resolution below the diffraction limit can enable new advances in neuroscience in the study of neurological disease, learning, memory and grief.

Biography: Juliet Gopinath is the Alfred T. and Betty E. Look Professor of Electrical, Computer and Energy Engineering and Physics at the University of Colorado Boulder. She received her B.S. degree in Electrical Engineering from the University of Minnesota and her M.S. and Ph.D. degrees at MIT. She was a member of technical staff at MIT Lincoln Laboratory from 2005 to 2009. Since then, she has led a research group at the University of Colorado Boulder. Her current research interests include ultrafast lasers, nonlinear optics, integrated photonic devices, spectroscopy and microscopy, quantum networking, structured light, and adaptive optical devices. She has published 103 peer-reviewed journal articles and over 140 conference presentations. She is the recipient of an AFOSR Young Investigator Award (2010), R&D 100 Award (2012), NSF CAREER (2016), University of Colorado Provost Achievement Award (2016), University of Colorado Engineering CEAS Research Award (2025), University of Colorado Boulder Faculty Award for Research (2026) and is an Optica Fellow (2021). She served as an Associate Editor for the IEEE Photonics Society Journal (2011-2017), the Associate Director for Cubit (2019), an Associate Editor for Optica (2020 – 2024), and is currently Secretary/Treasurer for APS Division of Laser Science (2023 – 2026) and Deputy Editor for Optica (2025-ongoing), as well as the 2026 program co-chair for the CLEO (Conference on Lasers and Electro-Optics) conference.

Juliet Gopinath

Windows into places unseen: Optical fiber-based quantum sensing and super-resolution imaging

Abstract: I will discuss our advances in quantum fiber sensing, showcasing how distributed fiber sensing can provide new information with enhanced sensitivity in optical fiber. The advancements will enable measurements in difficult to reach environments such as the ocean or underground. Additionally, I will describe our fiber-coupled super-resolution microscope that enables a window into the brain. We use a bend-insensitive donut that can be transmitted through commercially available fiber along with a Gaussian excitation beam to demonstrate stimulated emission depletion microscopy. Resolution below the diffraction limit can enable new advances in neuroscience in the study of neurological disease, learning, memory and grief.

Biography: Juliet Gopinath is the Alfred T. and Betty E. Look Professor of Electrical, Computer and Energy Engineering and Physics at the University of Colorado Boulder. She received her B.S. degree in Electrical Engineering from the University of Minnesota and her M.S. and Ph.D. degrees at MIT. She was a member of technical staff at MIT Lincoln Laboratory from 2005 to 2009. Since then, she has led a research group at the University of Colorado Boulder. Her current research interests include ultrafast lasers, nonlinear optics, integrated photonic devices, spectroscopy and microscopy, quantum networking, structured light, and adaptive optical devices. She has published 103 peer-reviewed journal articles and over 140 conference presentations. She is the recipient of an AFOSR Young Investigator Award (2010), R&D 100 Award (2012), NSF CAREER (2016), University of Colorado Provost Achievement Award (2016), University of Colorado Engineering CEAS Research Award (2025), University of Colorado Boulder Faculty Award for Research (2026) and is an Optica Fellow (2021). She served as an Associate Editor for the IEEE Photonics Society Journal (2011-2017), the Associate Director for Cubit (2019), an Associate Editor for Optica (2020 – 2024), and is currently Secretary/Treasurer for APS Division of Laser Science (2023 – 2026) and Deputy Editor for Optica (2025-ongoing), as well as the 2026 program co-chair for the CLEO (Conference on Lasers and Electro-Optics) conference.

Randy Bartels

Beyond the first moment: Quantum photon statistics for computational super-resolution microscopy

Abstract: Optical microscopy is fundamental to the study of complex biological and material systems, but its performance is limited both by diffraction and by the information retained in conventional intensity measurements. Standard imaging records only the mean photon flux, the first statistical moment of the optical field, and in doing so discards a richer hierarchy of fluctuations and correlations. Many super-resolution methods overcome classical resolution limits by manipulating probe photophysics. In contrast, our group develops computational approaches that recover spatial information directly from higher-order photon statistics, without relying on the state-switching strategies used in many established methods.

In this talk, I will discuss the physical principles and computational foundations of using non-classical photon statistics from quantum emitters to reveal otherwise hidden spatial detail. In particular, I will present antibunching-based super-resolution microscopy. Because an individual fluorophore must re-excite before emitting again, its fluorescence exhibits antibunching: photons are emitted with correlations that deviate from Poissonian statistics on short timescales. These higher-order correlations contain elevated spatial frequency information that is absent from conventional intensity images. By measuring photon arrival correlations and incorporating higher-order Glauber correlation functions into computational reconstruction algorithms, we recover structure that remains inaccessible to classical integration alone.

To enable practical, high-speed quantum-enhanced imaging, we combine parallelized correlation detection with structured illumination using Single Pixel Imaging with Frequency Modulation (SPIFI). In this framework, stepped spatial-frequency modulation encodes spatial information into the temporal domain, creating a natural interface between structured illumination and photon-correlation analysis. Finally, I will describe our use of Single-Photon Avalanche Diode (SPAD) arrays to capture photon statistics with single-photon sensitivity, high timing precision, and scalable parallel readout. Together, quantum photon statistics, SPIFI-based encoding, and SPAD-enabled computation establish a framework in which optical fluctuations become a practical resource for super-resolution microscopy.

Bio: Randy A. Bartels is an Investigator at the Morgridge Institute for Research and Professor of Biomedical Engineering at the University of Wisconsin–Madison. His work focuses on developing new optical imaging and spectroscopy methods that combine physical insight, advanced instrumentation, and computation to reveal information inaccessible to conventional measurements. He is a Fellow of the American Physical Society and Optica. His awards include the Presidential Early Career Award for Scientists and Engineers (PECASE), the Optica Adolph Lomb Medal, a Sloan Research Fellowship in Physics, and Young Investigator Awards from the NSF, ONR, the Beckman Foundation, and the IEEE Photonics Society. He serves on the editorial board of APL Photonics and is an editor for Science Advances.

Randy Bartels

Beyond the first moment: Quantum photon statistics for computational super-resolution microscopy

Abstract: Optical microscopy is fundamental to the study of complex biological and material systems, but its performance is limited both by diffraction and by the information retained in conventional intensity measurements. Standard imaging records only the mean photon flux, the first statistical moment of the optical field, and in doing so discards a richer hierarchy of fluctuations and correlations. Many super-resolution methods overcome classical resolution limits by manipulating probe photophysics. In contrast, our group develops computational approaches that recover spatial information directly from higher-order photon statistics, without relying on the state-switching strategies used in many established methods.

In this talk, I will discuss the physical principles and computational foundations of using non-classical photon statistics from quantum emitters to reveal otherwise hidden spatial detail. In particular, I will present antibunching-based super-resolution microscopy. Because an individual fluorophore must re-excite before emitting again, its fluorescence exhibits antibunching: photons are emitted with correlations that deviate from Poissonian statistics on short timescales. These higher-order correlations contain elevated spatial frequency information that is absent from conventional intensity images. By measuring photon arrival correlations and incorporating higher-order Glauber correlation functions into computational reconstruction algorithms, we recover structure that remains inaccessible to classical integration alone.

To enable practical, high-speed quantum-enhanced imaging, we combine parallelized correlation detection with structured illumination using Single Pixel Imaging with Frequency Modulation (SPIFI). In this framework, stepped spatial-frequency modulation encodes spatial information into the temporal domain, creating a natural interface between structured illumination and photon-correlation analysis. Finally, I will describe our use of Single-Photon Avalanche Diode (SPAD) arrays to capture photon statistics with single-photon sensitivity, high timing precision, and scalable parallel readout. Together, quantum photon statistics, SPIFI-based encoding, and SPAD-enabled computation establish a framework in which optical fluctuations become a practical resource for super-resolution microscopy.

Bio: Randy A. Bartels is an Investigator at the Morgridge Institute for Research and Professor of Biomedical Engineering at the University of Wisconsin–Madison. His work focuses on developing new optical imaging and spectroscopy methods that combine physical insight, advanced instrumentation, and computation to reveal information inaccessible to conventional measurements. He is a Fellow of the American Physical Society and Optica. His awards include the Presidential Early Career Award for Scientists and Engineers (PECASE), the Optica Adolph Lomb Medal, a Sloan Research Fellowship in Physics, and Young Investigator Awards from the NSF, ONR, the Beckman Foundation, and the IEEE Photonics Society. He serves on the editorial board of APL Photonics and is an editor for Science Advances.

Yamuna Phal

Mid-Infrared Technologies for Biosensing & Material Characterization

The mid-infrared (mid-IR) region of the electromagnetic spectrum, also known as the molecular fingerprint region, has long been a focus of scientific and technological research. Mid-IR microscopy is a non-destructive tool that can measure the molecular content of biological samples by probing fundamental vibrational modes, with potential applications in early disease detection and diagnosis. However, limitations such as long acquisition times, limited spatial detail, and a lack of understanding of light-matter interactions have impeded progress in this field. In this talk, I will present advanced mid-IR spectroscopic imaging platforms that address these challenges to improve perceived spatial resolution and enabling label-free classification of surgical tissue sections within minutes. Additionally, I will discuss the development of technology for imaging site-specific chirality of molecules, including the specific challenges and roadblocks to creating a viable and accurate system. The focus of this talk is on using theory and modeling to guide the development of measurement systems and open new opportunities for sensing biomolecules – in both terrestrial and space environments.

Yamuna Phal

Mid-Infrared Technologies for Biosensing & Material Characterization

The mid-infrared (mid-IR) region of the electromagnetic spectrum, also known as the molecular fingerprint region, has long been a focus of scientific and technological research. Mid-IR microscopy is a non-destructive tool that can measure the molecular content of biological samples by probing fundamental vibrational modes, with potential applications in early disease detection and diagnosis. However, limitations such as long acquisition times, limited spatial detail, and a lack of understanding of light-matter interactions have impeded progress in this field. In this talk, I will present advanced mid-IR spectroscopic imaging platforms that address these challenges to improve perceived spatial resolution and enabling label-free classification of surgical tissue sections within minutes. Additionally, I will discuss the development of technology for imaging site-specific chirality of molecules, including the specific challenges and roadblocks to creating a viable and accurate system. The focus of this talk is on using theory and modeling to guide the development of measurement systems and open new opportunities for sensing biomolecules – in both terrestrial and space environments.