Topological Quantum Device Lab

Quantum Hall Physics

Ultra High Mobility Device Physics
Integer/Fractional Quantum Hall Effect
Quantum Anomalous/ Spin Hall Effect
Integer/Fractional Chern Insulator

Recent advances in fabricating van der Waals heterostructures, along with improved cleaning procedures, have significantly enhanced the quality of graphene samples. This breakthrough enables us to anticipate the emergence of delicate correlated ground states in 2D electron systems. Graphene, with its unique Coulomb interaction characteristics, offers new possibilities, especially when the partially filled Landau level has a non-zero orbital index. Our ongoing research focuses on discovering fragile quantum Hall ground states in various 2D materials. Stay tuned for updates on our exploration of these intriguing phenomena

Ref

Y.Kim et al, Nano Letters 15, 7445–7451 (2015)

Y.Kim et al, Nature Physics 15, 154-159 (2019)

Y.Kim et al, Nano Letters 21, 4249–4254 (2021)

courtesy for figure to Daniela, Beni, and vK

Quantum Circuit

Fractional Quantum Hall Effect, Fractional Chern Insulator
Topological Quantum Computation
Abelian/non-Abelian Anyonic Braiding Statistics
Spin Qubit based on Bilayer Graphene Quantum Dots
Microwave Quantum Circuit

Anyons are exotic quasiparticles that defy classification as fermions or bosons, as they can assume any phase when exchanged. They hold promise for quantum information encoding through braiding, where particles circle one another. Recent advancements in fractional quantum Hall edge interference devices have probed anyons.

Currently, there are various fractional quantum Hall states, mainly characterized by the composite fermion model with Abelian anyons, starting with the Laughlin wave function. However, even more exotic quantum states exist, like v = 5/2 and v = 12/5. These states are chiral p-wave paired states of composite fermions, representing topological bound states of electrons and quantized vortices. They exhibit non-Abelian anyonic statistics, opening the door to topological quantum computing.

In 2+1 dimensions, with 2 representing the two-dimensional system and 1 as the time dimension, the direction of knots yields different outcomes, allowing for topologically protected and fault-tolerant quantum computing processes.

Exciting developments in anyon research hold the potential for transformative advancements in topological quantum computing.

Artificial Topological 2D Materials

2D Materials, van der Waals Heterostructure, Layer Coupling, Spin Device
Twisted bilayer physics, Spin-Orbit Coupling, Superconductivity

The exploration of two-dimensional electron systems with exceptionally low levels of disorder was previously limited to the epitaxial thin film research community. However, the advent of graphene, isolated through mechanical exfoliation, has brought about a significant disruption. Additionally, the assembly of heterostructures by stacking multiple layers of different 2D materials using van der Waals forces has revolutionized the field of low-dimensional physics.

In this project, we will carefully choose two or more distinct 2D materials, each possessing unique ground states such as metal, ferromagnet, or superconductor. By stacking these materials together, we aim to combine their properties and embark on a journey into uncharted territories.

Join us as we venture into this new realm, where the possibilities for scientific discovery and technological advancements are boundless.

Ref

Y. Kim et al, Physical Review Letters 110, 096602 (2013)

Y. Kim et al, Nano Letters 16, 5053–5059 (2016)

S. Mashhadi* and Y. Kim* et al, Nano Letters 19, 4659-4665 (2019)

Y. Kim et al, Nano Letters 21, 4249–4254 (2021)