Research


Our group performs nanoscale imaging and electronic device measurements to study the fundamental properties of quantum materials.

Quantum LEGOs: engineering new states of matter out of nanoscale building blocks

    The remarkable electronic properties of graphene have sparked interest in layered heterostructures of 2D crystals and broader classes of low-dimensional quantum materials. Driven by advances in the assembly of heterostructures of 2D materials, our group focuses on engineering new functionalities by tuning the twist angle between neighboring sheets or combining materials with contrasting properties into hybrid structures. We seek to investigate new regimes where many body interactions, quantum confinement, the wavelike nature of electrons, or topology plays a dominant role.
Review Article:
Sandwich Structures of 2D Atomic Crystals


Quantum technologies based on topological materials

    Topological solids can host electronic states that are protected from backscattering, manifested in conductance quantization that is remarkably independent of the shape or dimensions of the material. We aim to leverage topological excitations to enable fundamentally new forms of quantum computation that are more robust than conventional charge or spin-based platforms. Using nanofabrication techniques, we construct mesoscopic semiconductor – superconductor devices and develop techniques to experimentally detect nonabelian statistics.
    We also employ scanning probe microscopy to visualize topological states in emerging materials, including magnetic topological insulators, Weyl semimetals, and new candidates for the quantum spin Hall effect.
Review Article:
Topological Quantum Computation:
From Basic Concepts to First Experiments


Nanoscale imaging and sensing with microwaves

    In the Allen lab, we conceive, design, and construct novel microwave imaging techniques for condensed matter physics, with the goal of visualizing and manipulating electronic states at ultra-low temperatures down to 10 mK. Our scanning microwave microscope quantifies the complex microwave response of a material, providing a local measurement of dissipation and screening in response to high frequency electromagnetic fields from the tip.
    By developing spatially-resolved and time-resolved measurement capabilities at frequencies across the GHz regime, we aim to shed new light onto topological edge states, Majorana modes, edge magnetoplasmons, domain wall conduction in new materials.

Keywords:

Scanning probe microscopy, quantum transport, topological states of matter, graphene and novel low dimensional systems, superconductivity, and solid state realizations of quantum information processing.


Selected Publications: