Pioneer of experimental quantum optics with entangled and hyper-entangled photons; research spans quantum information processing, quantum communication, quantum-enhanced metrology and sensing, and fundamental tests of quantum mechanics using single- and entangled-photon sources.

Develops single-molecule spectroscopy and imaging/signal-processing methods to study protein dynamics at interfaces and predictive separations.

Develops mass spectrometry-based imaging and proteomics technologies, including integration of tissue expansion microscopy with mass spectrometry imaging to achieve higher spatial resolution molecular maps of tissues such as tumors and brain.

Studies photophysics and photochemistry of plasmonic nanomaterials using single-particle optical imaging and ultrafast spectroscopy, with applications to solar energy conversion.

Studies active galactic nuclei, supermassive black hole binaries, and time-domain phenomena using large optical/IR spectroscopic and imaging surveys.

Directs the Laboratory for Astronomical Imaging; develops millimeter/submillimeter interferometric imaging instrumentation (e.g., for ALMA) and studies star and protoplanetary disk formation.

Works in quantum optics and AMO physics: generation, characterization, and engineering of photonic quantum states, atomic and solid-state quantum memories, single-photon-level atomic/molecular spectroscopy, and optical magnetometry for quantum sensing; leads UIUC's public quantum network project.

Studies galaxy formation and evolution using spectroscopic surveys of high-redshift galaxies with JWST and other facilities.

Studies the structure, kinematics, and dynamics of star clusters and star-forming regions, stellar binary populations, and alternative stellar-evolution pathways such as blue stragglers.

Develops cryogenic microcalorimeter/TES-based X-ray and far-infrared detector arrays used in X-ray astronomy and CMB instrumentation.