Associate ProfessorMaterials Science and EngineeringUniversity of Maryland
My group studies what electrons and excitons do in two-dimensional semiconductors when Coulomb interactions dominate. We build the van der Waals heterostructures that host Wigner crystals, moiré Mott and Hall insulators, and long-lived interlayer excitons, and we develop the optical spectroscopies that read these phases out and reshape them: polaron dressing, atomically thin mirrors and cavities, and lattices for excitons far below the diffraction limit. The long-term aim is quantum matter that can be engineered with light and used as a resource for quantum simulation and quantum photonics.
Research program Publications Google Scholar CV (PDF) youzhou@umd.edu
The program
One question, approached in three coupled ways.
When electrons and excitons in a two-dimensional semiconductor interact more strongly than they move, they organize into phases with no single-particle analogue. We make those phases, use excitons to measure them, and use engineered light–matter coupling to steer them.
Stacking MoSe2, WSe2, and hBN into gated heterostructures lets interlayer Coulomb interactions lock electrons into a bilayer Wigner crystal, lets moiré potentials produce excitonic Mott insulators and quantum anomalous Hall states, and keeps interlayer excitons tightly bound yet bright while a gate moves and gathers them.
Nature 2021 · PRL 2024 · Nat. Commun. 2024 · PRX 2025
An exciton placed in a correlated electron sea becomes a polaron, and its optical spectrum reports on the surroundings. Wigner polarons read out the stiffness, fluctuations, and melting of an electron crystal; attractive polarons reveal quantum anomalous Hall states in twisted WSe2; exciton diffusion senses the onset of a Mott insulator. Optics becomes a quantitative many-body probe.
A single semiconductor layer can act as a near-perfect, electrically switchable mirror, and two of them form a cavity a few atoms thick with chiral flat bands. Fermi-polaron resonances give an optical nonlinearity strong enough to matter at low light levels, and plasmonic or electrostatic lattices confine excitons on scales far smaller than the wavelength of light.
PRL 2018 · PRL 2020 · Nat. Photonics 2024 · Sci. Adv. 2024 · Sci. Adv. 2025 · PRL 2025
Signature results
Five results, chosen for what they opened up.
Nature · 2021
In a MoSe2/hBN/MoSe2 heterostructure, interlayer Coulomb interactions lock the electrons of the two layers into an interlocking bilayer Wigner crystal. Excitons sense the crystal's formation, so their spectra map its phase diagram and its quantum melting as density and temperature are tuned.
This established exciton spectroscopy of van der Waals bilayers as a clean platform for electron crystals, and set up the questions the group has pursued since: how such crystals move, melt, and can be read out.
Zhou et al., Nature 595, 48 (2021)
Coverage: Quanta Magazine · Harvard Gazette · Journal Club for Condensed Matter Physics
Nature Physics · 2026
Excitons injected into a monolayer Wigner crystal are dressed by the crystal's own distortion and form Wigner polarons. Their spectra give direct access to the crystal's stiffness, its quantum and thermal fluctuations, and the way it melts.
A crystal made entirely of electrons leaves almost no fingerprint for conventional probes. Wigner polarons turn every exciton into a built-in sensor, opening an optical window on the dynamics of electron crystals in general. With collaborators at ETH Zurich, Heidelberg, and Brookhaven.
Zhang et al., Nature Physics (2026)
Coverage: Phys.org · Maryland Today
Nature Photonics · 2024
In electrically gated, atomically thin WSe2, the Fermi-polaron resonance of excitons in an electron gas responds nonlinearly at remarkably low light levels, switching the material from absorbing to transmitting, and the effect is turned on and off with a gate voltage.
A strong, tunable nonlinearity in a solid a few atoms thick is the prerequisite for few-photon optical switches and quantum photonic devices. A patent application covers the device concept.
Gu et al., Nature Photonics 18, 816 (2024)
Coverage: DOE Office of Science highlight · Nature Photonics News & Views · Brookhaven National Laboratory
PRL · 2018, 2020 · Science Advances · 2024
Excitons in high-quality monolayer MoSe2 release their energy almost entirely as light, so a single layer reflects like a near-perfect mirror whose reflectance switches with a gate voltage. Moving such a layer relative to a mirror tunes exciton radiative lifetimes in real time, and two monolayer mirrors form an optical cavity with chiral flat bands.
These are the building blocks for photonic structures made from the semiconductor itself: metasurfaces, nanosecond beam steering, and cavity quantum electrodynamics without a separate mirror stack.
Scuri*, Zhou* et al., PRL 120, 037401 (2018) · Zhou et al., PRL 124, 027401 (2020) · Suárez-Forero et al., Sci. Adv. 10, eadr5904 (2024)
Coverage: Nature · Physics · Chemistry World
Science Advances · 2025 · PRL · 2025
A nanopatterned silver surface converts laser light into plasmon polaritons that imprint a periodic potential on excitons in a nearby monolayer: an optical lattice with a period far below the wavelength of light, at roughly a hundred times lower laser power than direct illumination. Separately, the in-plane fields at the domain walls of twisted hexagonal boron nitride trap excitons in narrow one-dimensional channels.
Lattices are how cold-atom experiments turn interacting particles into programmable quantum matter. Bringing them to excitons, optically and electrostatically, is the route to light-driven correlated phases and to arrays of quantum emitters.
Sarkar et al., Sci. Adv. 11, eadv2023 (2025) · Gu et al., PRL 135, 026901 (2025)
Where this is heading
Three directions the group is funded to pursue.
Coupled electron and hole layers should crystallize together and, at higher density, condense. Tightly bound interlayer excitons that we can gate and transport, together with dark interlayer excitons and interlayer polarons now under study, are the ingredients.
DOE Early Career Award · NSF CAREER
Sub-wavelength optical lattices and atomically thin cavities become programmable potentials for excitons and polarons. The goal is correlated phases whose geometry and interactions are set by light rather than by chemistry, and read out through the same photons.
Army Research Office · NSF QLCI Institute for Robust Quantum Simulation, Phase II
Few-photon nonlinearities from Fermi polarons, chiral cavities, and moiré-confined excitons point toward single-photon-level switches and nonclassical light sources built from correlated electrons. Materials for quantum information science is the subject of an invited review from the group (arXiv:2609.09371).
DARPA · NSF ExpandQISE
Recognition
Research support: National Science Foundation, Department of Energy, Army Research Office, DARPA, and Oak Ridge Associated Universities.
Recent news
Our paper on Wigner polarons is published in Nature Physics. Featured in Phys.org and Maryland Today.
The NSF Quantum Leap Challenge Institute for Robust Quantum Simulation, in which You Zhou is a Senior Investigator, is renewed for Phase II.
Our collaborative paper on quantum anomalous Hall states, read out by attractive-polaron spectroscopy, is published in Physical Review X.
You Zhou is promoted to Associate Professor.
You Zhou receives the Junior Faculty Outstanding Research Award from the A. James Clark School of Engineering, University of Maryland.
Sabyasachi Das wins the 2026 FIAP Ken Hass Outstanding Student Paper Award at the APS March Meeting. Congratulations!