Zhou Lab at MarylandQuantum Materials and Optoelectronics Laboratory

Research

Quantum Materials and Optoelectronics

We work at the intersection of materials science, solid-state physics, and quantum optics. We focus on many-body physics, quantum optics in solids, and quantum electronics and optoelectronics. By integrating materials synthesis, nanofabrication, and low-temperature optical and electrical characterization, we study the fundamental physics of quantum many-body systems and develop ways to control it for device applications.

Many-body physics

Strong interactions cause electrons and excitons to organize into states with no single-particle description. We design atomically precise van der Waals heterostructures with gate control to explore these phases.

Several current topics of research include:

  1. Wigner crystals, their dynamics, and quantum phase transitions
  2. electronic and excitonic topological states, such as the quantum anomalous Hall effect
  3. strongly interacting mixtures of fermions, bosons, and anyons
  4. exciton condensation and superfluidity in coupled layers
Illustration of two interlocking triangular lattices of electrons, one violet and one gold, stacked as a bilayer crystal.
Electrons in two atomically thin layers (violet and gold) interlock into a bilayer Wigner crystal, stabilized by interlayer Coulomb interactions. Nature, 2021 · plain-language story

Quantum optics in solids

Excitons in clean monolayers couple to light strongly enough that a single atomic layer behaves as an optical element. Interactions among those excitons can in turn be engineered, which makes these materials a testbed for quantum optics inside a solid.

Several current topics of research include:

  1. giant optical nonlinearity from excitons interacting with free carriers
  2. quantum confinement of excitons for excitonics and nonlinear optics
  3. strong light–matter coupling for polaritons and quantum nonlinear optics
Illustration of a laser beam striking a stack of atomically thin layers, with charges drawn as small spheres among the atoms.
A laser beam on an atomically thin semiconductor filled with free charges (small spheres). Excitons dressed by these charges, Fermi polarons, give a giant optical nonlinearity that a gate voltage tunes. Nature Photonics, 2024 · plain-language story

Quantum electronics and optoelectronics

Strong light–matter coupling, long coherence, and a large response to gates, strain, and light make these heterostructures natural device platforms. We turn that control into quantum electronic and optoelectronic devices, from radio-frequency electronics to fast, energy-efficient optical modulators.

Several current topics of research include:

  1. radio-frequency electronics based on 2D materials
  2. metasurface-enhanced optoelectronic and photonic devices
  3. active optical devices that are energy efficient and ultrafast
Illustration of an optical cavity made of two atomically thin mirrors: two square semiconductor monolayers, drawn atom by atom, face each other, with glowing light trapped between them as a standing wave and a blue helix wound around it for its circular polarization.
Two atomically thin mirrors form a cavity that traps light as a standing wave (the helix marks its circular polarization) and supports photonic flat bands and chiral coupling. Science Advances, 2024 · plain-language story

Facilities

In the lab

  • Optical spectroscopyOptical cryostat with tunable and pulsed lasers · Confocal reflectance, photoluminescence and time-resolved spectroscopy, 400–1700 nm · Photon correlation g(2), interferometry and Fourier-plane imaging
  • Electrical and radio-frequencyCryogenic probe station, closed-cycle helium, to 40 GHz · Vector network analyzer, to 40 GHz · Transport and capacitance electronics
  • Fabrication and sample tuningPulsed laser deposition · Ultra-high-vacuum chamber for atomic vapor and sample annealing · van der Waals transfer stage · Piezoelectric cell for low-temperature optical and electrical measurements under in situ strain