Exploring electron behaviors—topology, correlation, entanglement—and beyond. No boundaries, just discovery.

Experimental Techniques

Our effort includes the development of multifunctional scanning probe techniques, which we have named RFlexiScope, to offer integrated functionalities. We are also expanding the frequency range of spectroscopy studies and driving measurement techniques from the semiclassical to the quantum regime.

Characterization of two fast-turnaround dry dilution refrigerators for scanning probe microscopy, Journal of Low Temperature Physics, 2024

Transmission-mode microwave impedance microscopy using a photonic crystal cavity at sub-THz frequencies, APS abstract, 2024

  • We are developing RFlexiScope, an advanced tool for scanning probe and on-chip sensing of quantum materials, capable of detecting inductance, resistance, and capacitance in the microwave regime. By further integrating traditional DC and optical frequency methods, we aim to probe some of the most fundamental and challenging physical quantities in condensed matter physics, including topological and geometrical phases, nonlocality, quantum noise, and entropy.

    RFlexiScope 1.0 is currently under development at SLAC, and will be upgraded at MIT. Our ambition is to extend RFlexiScope into the quantum regime, enabling coherent and highly precise measurements of elusive quantities, such as quantum entanglement entropy. This technique is essential to uncovering the deeper nature of quantum materials.

  • We build confocal optical spectroscopy around a dilution refrigerator to facilitate study of quantum phases that appear only at mK temperatures and subjected to high magnetic fields, down to the single photon limit.

  • With the goal of creating miniature quantum circuits using quantum materials and with strong support from MIT.nano, our research employs 2D sample fabrication techniques such as dry transfer and stacking, quantum device fabrication methods like high-precision electron beam lithography, and junction deposition.

  • We are working to automate experiments, minimize repetitive tasks (such as locating small sample flakes before scanning), and implement on-the-fly data analysis to enhance efficiency in discovering new quantum phases and exploring the parameter spaces of materials.

    Relevant readings: Capturing dynamical correlations using implicit neural representations, Nat. Comm. (2023)

Local and Nonlocal Studies of Topological States

Our research is driven by a fascination with the diverse quantum states and exotic properties that emerge from the interplay of topology, geometry, and correlations. We aim to discover new phases of matter and study the nature of their quasiparticle excitations. Specifically, we push beyond conventional methods to “excite” and “detect” nonlocally, offering unique insights into bulk-edge correspondence, quantum criticality, and signatures of electron entanglement in topologically ordered states (Wen, 1990). Engaging with the strong community at MIT, we hope to gain a deeper understanding of the strongly correlated behaviors of electrons.

Local probe of bulk and edge states in a fractional Chern insulator, Nature, 2024

Opto-twistronic Hall effect in a three-dimensional spiral lattice, Nature, 2024

  • Topological ordered states, such as fractional quantum Hall states, where interactions and topology interplay, have gained significant attention for their importance in fundamental physics and potential applications in topological quantum computation. However, their ground state remains elusive and not fully understood.

    Its characteristics has three major aspects: (1) Having topologically protected gapless boundary excitations 2) The finite-energy defects of topological order, i.e., the quasiparticles, can carry fractional statistics (including non-Abelian statistics) and fractional charges. (3)Topological orders producing new kind of waves, i.e., the collective excitations above the topologically ordered ground states.

    With its ability to sense bulk and edge separately and capture collective excitations locally, RFlexiScope provides an unique access to all three defining characteristics of topologically ordered states.

  • In correlated phases are quasiparticles excitations that has classical nonlocality in their electromagnetic responses. One example is the composite fermions at zero magnetic field, and the intriguing physics of anyons. We will use the advanced nonlocal measurement techniques to explore those quasiparticle excitations, and gain understandings of the those phases.

Quantum Optoelectronics

Building on the momentum of the second quantum revolution, we explore quantum optoelectronic studies as a dynamic two-way process: uncovering new principles of light-matter interaction and associated material properties, while applying these findings to  design new quantum devices for sensing and circuitry.

Photocurrent detection of the orbital angular momentum of light, Science, 2020

Generation of helical topological exciton-polaritons, Science, 2020

  • Starting with density matrix calculations, we combine theory and experiments to uncover new response functions in light-matter interactions. Our focus includes exploring how cavity electrodynamics enhances many-body effects and how novel Hall effects emerge under acoustic, microwave, and optical drives.

  • We make new designs for nanoelectronic and nanophotonic devices based on 2D van der waals materials. We use those “LEGO bricks” formed by these atomically thin materials to explore coherent excitations and highly tunable nonlinearities.

    We then develop ultracompact quantum circuits. One example is 2D transitional metal dichalcogenide based entangled photon pair generation and detection.