Developing quantum computers relies heavily on establishing a stable network of qubits for storing information, accessing it, and conducting computations. However, existing qubit platforms have a common issue: they are often fragile and susceptible to external disturbances. Even a slight interference like a stray photon can disrupt their operations. The key to overcoming this challenge lies in developing fault-tolerant qubits that are resistant to external disturbances.
A team of scientists and engineers at the University of Washington has made a significant breakthrough in this area. Through experiments with semiconductor materials, they have identified signatures of “fractional quantum anomalous Hall” (FQAH) states.
These FQAH states can accommodate anyons, which are peculiar “quasiparticles” with a fraction of an electron’s charge. This discovery marks a promising step towards constructing a specific type of fault-tolerant qubit that can be “topologically protected” and remain stable in the face of minor disruptions.
Lead researcher Xiaodong Xu commented, “This sets a new standard for exploring quantum physics with fractional excitations in the future.”
The FQAH state is a rare phase of matter that exists in two-dimensional systems and exhibits limited electrical conductivity in precise fractions of the conductance quantum. While traditional fractional quantum Hall systems require strong magnetic fields for stability, the FQAH state remains stable even at zero magnetic fields.
To host this exotic phase of matter, the scientists created an artificial lattice with unique properties by stacking two atomically thin flakes of a semiconductor material called molybdenum ditelluride (MoTe2) at a slight angle. This configuration formed an artificial “honeycomb lattice” for the electrons.
By cooling the stacked flakes to near absolute zero, the configuration generated intrinsic magnetism, eliminating the need for a strong external magnetic field. The researchers used lasers as probes to detect signatures of the FQAH effect, marking a significant advancement in understanding anyons and their potential for quantum computing.
The team envisions their system as a robust platform for studying anyons and aims to discover “non-Abelian” anyons that could serve as topological qubits in future experiments. These topological qubits, based on the braiding of non-Abelian anyons, offer enhanced resilience against local disruptions, making them a promising avenue for quantum computing.
Doctoral student Eric Anderson noted, “This type of topological qubit would be fundamentally different from current qubits and could offer greater stability as a quantum computing platform.”
The experimental setup showcases three key properties simultaneously: Magnetism, Topology, and Interactions. The researchers believe that non-Abelian anyons hold the key to future advancements in quantum computing.
Co-lead author Jiaqi Cai expressed, “The observed signatures of the fractional quantum anomalous Hall effect are inspiring and could lead to new discoveries in quantum physics and applications.”
Xiaodong Xu added, “Our work provides clear evidence of the elusive FQAH states, and we are currently conducting electrical transport measurements to further validate the existence of fractional excitations at zero magnetic fields.”
Journal Reference:
- Cai, J., Anderson, E., Wang, C. et al. Signatures of Fractional Quantum Anomalous Hall States in Twisted MoTe2. Nature (2023). DOI: 10.1038/s41586-023-06289-w
