About

Norbert Scherer is a Professor in the Department of Chemistry at The University of Chicago with a research focus on biophysics, materials chemistry, and physical chemistry. His group explores a wide range of experimental and simulation methods to address questions related to formation, structure, and dynamics in driven nonequilibrium optical matter; optical magnetism and collective excitations in nanoplasmonic-based meta-materials; and the connection between transport processes in single and multicellular systems to their functions. His work involves developing new methods such as ultrafast lasers, nonlinear spectroscopy, advanced microscopy, and coupled electrodynamics and Langevin dynamics simulations. Scherer's research has pioneered the self-organization of nanoparticle assemblies into optical matter structures capable of directed motion and collective behavior, including the creation of nanoscale optical machines that convert spin to orbital angular momentum. His studies extend to the optical properties of hybrid nanostructures, including the enhancement of radiative properties of quantum dots within self-organized lattices, with implications for lasing and quantum materials exhibiting entanglement. Additionally, his group investigates novel optical excitations enabled by vector beams of light, such as optical magnetism and dark modes in meta-atoms, advancing the understanding of matter-radiation interactions at the nanoscale. In cellular biophysics, Scherer studies intracellular transport mechanisms, particularly the movement of insulin-containing vesicles in beta cells, aiming to relate transport dynamics to cell function and disease phenotypes like diabetes. His work employs advanced particle tracking, machine learning, and imaging techniques to analyze the complex, out-of-equilibrium behavior of cellular components, with a focus on understanding how transport processes influence cellular activity and function.

Research topics

• Materials science
• Physics
• Optics
• Chemistry
• Molecular physics

Selected publications

• Pseudorotation and N-body Forces in an Optical Matter System

  Open MIND · 2026-02-11

  preprintSenior author

  Isomerization in molecular systems almost invariably occurs through 3-dimensional motion due to the nature of chemical bonding. Pseudorotation is an unusual type of isomerization that occurs in some high symmetry systems that gives the appearance of rigid-body rotation yet only involves atom rearrangements. This paper demonstrates that pseudorotation occurs in 2-dimensions in an optical matter (OM) system of metal nanoparticle constituents. The difference in dimensionality of the dynamics arises from the electrodynamic field-interference nature of optical binding vs. quantum mechanical bonding in polyatomic molecules. The 8-nanoparticle OM "kite" structure we study in experiments and simulations has D2 (D2h) symmetry and a D4 symmetric transition state. The mechanism for pseudorotation involves correlated motion of all 8 nanoparticles with smooth (continuous) evolution of their interactions and without particles jumping in or out of the OM array. While the OM kite structure only occurs with 10% probability vs. other OM isomers, its rate of pseudorotation is rapid relative to transitions to other structural isomers (e.g., "teardrop"). The other isomers have structures that lie on a trigonal lattice with inter-particle separations at distances that enhance field interference and induced polarizations. Even though the kite isomer has inter-particle separations that would manifest destructive interference on a particle pair (i.e., 2-body) basis, the kite structure is the slowest to rearrange into any other isomer. We show that the unusual structure and dynamics of the kite optical matter system result from N-body interactions and forces demonstrating that N-body effects are important in this class of active matter and presumably more generally.

  DOI

• Pseudorotation and N-body Forces in an Optical Matter System

  arXiv (Cornell University) · 2026-02-11

  articleOpen accessSenior author

  Isomerization in molecular systems almost invariably occurs through 3-dimensional motion due to the nature of chemical bonding. Pseudorotation is an unusual type of isomerization that occurs in some high symmetry systems that gives the appearance of rigid-body rotation yet only involves atom rearrangements. This paper demonstrates that pseudorotation occurs in 2-dimensions in an optical matter (OM) system of metal nanoparticle constituents. The difference in dimensionality of the dynamics arises from the electrodynamic field-interference nature of optical binding vs. quantum mechanical bonding in polyatomic molecules. The 8-nanoparticle OM "kite" structure we study in experiments and simulations has D2 (D2h) symmetry and a D4 symmetric transition state. The mechanism for pseudorotation involves correlated motion of all 8 nanoparticles with smooth (continuous) evolution of their interactions and without particles jumping in or out of the OM array. While the OM kite structure only occurs with 10% probability vs. other OM isomers, its rate of pseudorotation is rapid relative to transitions to other structural isomers (e.g., "teardrop"). The other isomers have structures that lie on a trigonal lattice with inter-particle separations at distances that enhance field interference and induced polarizations. Even though the kite isomer has inter-particle separations that would manifest destructive interference on a particle pair (i.e., 2-body) basis, the kite structure is the slowest to rearrange into any other isomer. We show that the unusual structure and dynamics of the kite optical matter system result from N-body interactions and forces demonstrating that N-body effects are important in this class of active matter and presumably more generally.

  PublisherOA PDF

• Optical trapping with optical magnetic field and photonic Hall effect forces

  Nature Communications · 2025-11-24

  articleOpen accessSenior author

  Optical trapping offers robust nanoscale control of matter but, to date, has been dominated by the interaction between a material’s electric polarizability, αe, and the electric part of light, therefore defined by electric-field intensity-gradient forces. Magnetic light-matter interactions, despite their potential to reshape optical trapping research, have remained experimentally unrealized. This paper addresses this long-standing deficiency by realizing optical magnetic field-associated trapping of high-index (i.e., Si) nanoparticles. Experiments, validated by our theoretical framework and Maxwell stress tensor calculations, reveal the essential role of a material’s magnetic polarizability, αm, and electric-magnetic scattering forces arising from the photonic Hall effect. This magnetic contribution allows exploration of stable trapping, distinct from purely electric-field control. Our findings open avenues for nanoparticle manipulation beyond conventional paradigms, enable previously unexamined optical matter formation driven by magnetic interactions, and suggest unexplored N-body effects and symmetry-breaking dynamics in optical matter systems. The authors achieve magnetic trapping at optical frequencies and uncover photonic Hall effect forces by engineering spatially isolated magnetic fields interacting with a single Si nanoparticle at its magnetic dipole resonance.

  PublisherOA PDFDOI

• Non-Equilibrium Dynamics and Non-Gaussian Fluctuations of an Optical Matter System Manifesting Pseudorotation

  ACS Nano · 2025-10-08

  articleSenior authorCorresponding

  Gaussian fluctuations are intrinsic to systems in thermal equilibrium and are also a tenet of near-equilibrium systems related by linear response. We recently introduced a Gaussian (fluctuation) approximation to demonstrate that the entropy production rate and power dissipation are equal to each other in multiparticle overdamped nonconservative nonequilibrium systems. The fluctuations of the nanoparticle constituents of the optical matter (OM) systems studied, characterized through their collective modes of motion, satisfied the Gaussian approximation. Here, we report a type of collective mode and motion in a different OM system that manifests strong non-Gaussian behavior. We show through experiments and simulations that the collective motion is a pseudorotation of the overdamped and nonconservative 8-silver-nanoparticle OM structure in water. The OM system has D2 point group symmetry (in 2-dimensional space) and exists in a nonequilibrium steady state (NESS) at various temperatures and solution ionic strengths. We developed a weighted principal component analysis (w-PCA) and state-free nonreversible VAMPnet (Variational Approach to Markov Process solved via neural network) method to identify the collective modes of the nanoparticle motion and the time scales of their dynamics, including pseudorotation. We show that the confinement exerted by the outer four particles on the inner four particles has a significant temperature-dependent impact on the pseudorotation dynamics. We attribute the counterintuitive change of the dynamics with increasing temperature─changing from monomodal Gaussian-like to bimodal with the same mean─to the implicit nature of the interparticle interactions and resultant forces. The nonconservative force field determined at each time step of our simulations is an intrinsic characteristic of these nonequilibrium many-body interacting OM systems. We anticipate that our w-PCA+VAMPnet method will be useful in studies of collective motions of complex overdamped and nonconservative systems, and of particle dynamics in other systems such as cluster liquids (e.g., liquid sulfur).

  PublisherDOI

• Micro𝕊plit: Semantic Unmixing of Fluorescent Microscopy Data

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-02-11 · 5 citations

  preprintOpen access

  Abstract Fluorescence microscopy, a key driver for progress in the life sciences, faces limitations due to the microscope’s optics, fluorophore chemistry, and photon exposure limits, necessitating trade-offs in imaging speed, resolution, and depth. Here, we introduce Micro𝕊plit, a computational multiplexing technique based on deep learning that allows multiple cellular structures to be imaged in a single fluorescent channel and then unmix them by computational means, allowing faster imaging and reduced photon exposure. We show that Micro𝕊plit efficiently separates up to four superimposed noisy structures into distinct denoised fluorescent image channels. Furthermore, using Variational Splitting Encoder-Decoder (VSE) networks, our approach can sample diverse predictions from a trained posterior of solutions. The diversity of these samples scales with the uncertainty in a given input, allowing us to estimate the true prediction errors by computing the variability between posterior samples. We demonstrate the robustness of Micro𝕊plit networks, which are trained for each splitting task at hand, across various datasets and noise levels and show its utility to image more, to image faster, and to improve downstream analysis. We provide Micro𝕊plit along with all associated training and evaluation datasets as open resources, enabling life scientists to immediately benefit from the potential of computational multiplexing and thus help accelerate the rate of their scientific discovery process.

  PublisherDOI

• Multi-scan structured illumination microscopy for rapid and efficient volumetric super-resolution imaging

  Optics Letters · 2025-04-24 · 1 citations

  articleSenior author

  Structured illumination microscopy (SIM) is a widely adopted super-resolution imaging technique. Conventional 3D-SIM requires at least 15 exposures at each z-plane to achieve ∼2 × improved lateral and axial resolution. However, this requirement for a large number of exposures for "super-resolution" exacerbates photobleaching and slows imaging speed, thus significantly limiting its application in volumetric biological imaging. Here, we introduce multi-scan SIM (MS-SIM) that integrates a simple beam splitter for simultaneously imaging three different focal planes and a deformable mirror that enables rapid z-scanning over three contiguous sub-volumes. We demonstrate the MS-SIM system through high-quality live whole cell SIM imaging at ∼1 Hz. The high efficiency and flexibility of MS-SIM can significantly impact 3D super-resolution imaging of biological and dense colloidal systems.

  PublisherDOI

• Symmetry breaking-induced N-body electrodynamic forces in optical matter systems

  Nature Communications · 2025-07-08 · 6 citations

  articleOpen accessSenior author

  Breaking symmetry can give rise to non-reciprocal forces–unequal and opposite forces–typically observed in active matter systems involving asymmetric 2-body interactions. So far, there are few examples of N-body non-reciprocal forces induced by symmetry breaking. Here we show, through experiment, numerical simulation, and theoretical analysis, that N-body non-reciprocal forces emerge in optical matter systems comprised of three or more electrodynamically interacting (nano)particles when spatial symmetries are broken. The requisite symmetry breaking is realized in experiment by trapping Ag nanoparticles in a curved geometry using an optical ring trap. The ordered ring of nanoparticles is observed to rotate collectively in a direction governed by the handedness of the trapping beam’s circular polarization. This force, distinct from spin-to-orbit angular momentum conversion, depends strongly on particle number and inter-particle separations. These N-body non-reciprocal interactions induced by symmetry breaking are general and should arise in other “coherently illuminated” active matter systems. Non-reciprocal forces due to symmetry breaking have been typically observed in active matter systems with two-body interactions. Here, by breaking the spatial symmetry of ‘dry’ active matter systems with many identical nanoparticles, the authors observe collective dynamics driven by N-body electrodynamic forces.

  PublisherOA PDFDOI

• Power dissipation and entropy production rate of high-dimensional optical matter systems

  Physical review. E · 2024-10-07 · 2 citations

  articleSenior author

  Entropy production is an essential aspect of creating and maintaining nonequilibrium systems. Despite their ubiquity, calculation of entropy production rates is challenging for high-dimensional systems, so it has only been reported for simple (i.e., l-particle) systems. Moreover, there is a dearth of nontrivial experimental systems where precise measurements of entropy production rate and characterization of the nonequilibrium steady state (NESS) are simultaneously possible. We report an approach to calculate the entropy production rate of overdamped, nonconservative, $N$-body systems and demonstrate this on a six-particle triangle optical matter (OM) system as a nontrivial example. OM systems consist of (nano-)particles organized into ordered arrays that are bound by electrodynamic interactions associated with the scattering and interference of light, and the associated induced-polarizations in and among the particles in coherent optical beams. The flux of laser light in OM systems in a solution environment necessitates that they dissipate energy, produce entropy, and relax to a NESS. The NESS may have several ordered particle configurations (i.e., isomers) that can interchange by barrier crossing processes. Understanding the power dissipation and entropy production rate of a NESS in an OM system along different (collective) modes of motion can advance understanding of the relative stability of the NESSs as well as inform design and control of OM structures. Therefore, we compute the components of the entropy production rate and power dissipation along the collective coordinates of the 6 Ag nanoparticle triangle OM system from OM NESS trajectory data and verify the Seifert relation [U. Seifert, Rep. Prog. Phys. 75, 126001 (2012)] for these complex systems with a nuanced interpretation.

  PublisherDOI

• 0ptical trapping with optical magnetic field and photonic Hall effect forces

  arXiv (Cornell University) · 2024-08-19 · 1 citations

  preprintOpen accessSenior author

  Optical trapping is having ever-increasing impact in science $-$ particularly biophysics, photonics and most recently in quantum optomechanics $-$ owing to its superior capability for manipulating nanoscale structures and materials. However, essentially all experimental optical trapping studies in the optical dipole regime have, to date, been dominated by the interaction between a material's electric polarizability, $α_{e}$, and the electric part of the incident electromagnetic field, and therefore described by electric field intensity gradient forces. Optical trapping based on optical magnetic light-matter interactions has not been experimentally addressed despite it's immediate extension of the boundaries of optical trapping research and applications. This paper addresses this long-standing deficiency through the realization of optical magnetic trapping of large index of refraction (i.e., Si) nanoparticles and also presents a formalism for quantitative understanding of the experimental findings. Our experimental optical trapping results require including optical magnetic polarizability, $α_{m}$, and electric-magnetic scattering forces associated with the Photonic Hall effect that are qualitatively and quantitatively validated by Maxwell stress tensor calculations. Our findings bring new opportunities for nanoparticle manipulation, potentially relax the limitations Ashkin claimed based on the optical Earnshaw's theorem, motivate optical matter formation by optical magnetic interactions, and suggest new N-body effects and symmetry breaking to drive dynamics of optical matter systems.

  PublisherOA PDFDOI

• Aberration-free, multi-plane, multi-color, and deep learning-empowered virtual multi-channel structured illumination microscopy

  Biophysical Journal · 2024-02-01

  articleSenior author
  PublisherDOI

Recent grants

• Creating and Probing Optical and Material Nonlinearities in Single Nanoparticles, Dimers, Clusters and Arrays

  NSF · $510k · 2006–2009

• NIH Grant R01GM057768

  NIH · $414k · 2001

• NIH Grant R01GM067961

  NIH · $1.1M · 2008

• Excitation Transport and Coherence in Nano-Plasmonic Wire Materials by Experiment and Simulation

  NSF · $516k · 2011–2014

Frequent coauthors

• David C. Arnett

  42 shared

• Stephen K. Gray

  35 shared

• Aaron R. Dinner

  33 shared

• Matthew Pelton

  33 shared

• Zijie Yan

  Shanghai Municipal Center For Disease Control Prevention

  27 shared

• Lewis D. Book

  Northrop Grumman (United States)

  27 shared

• Julie A. Gruetzmacher

  University of Chicago

  26 shared

• René A. Nome

  Universidade Estadual de Campinas (UNICAMP)

  26 shared

Labs

• Scherer LabPI

Education

• NSF Postdoctoral Fellow, Chemsitry

  University of Chicago

  1992

• PhD in Chemical Physics, Chemistry

  California Institute of Technology

  1989

• BS in Chemistry

  University of Chicago

  1982

Awards & honors

• Fellow, American Association for the Advancement of Science…
• Fellow, Optical Society of America 2015
• Peter Debye Prize 2015
• Department of Defense Vannevar Bush Faculty Fellowship 2014
• John Simon Guggenheim Memorial Foundation Fellowship 2006