Physicists at MIT have made a significant advancement in the field of quantum computing, demonstrating that it should be possible to create an exotic form of matter that could be manipulated to form qubits, the fundamental building blocks of future quantum computers. These quantum computers hold the potential to be vastly more powerful than those currently under development. The new research, published in Physical Review Letters on October 17, builds on a discovery from the previous year regarding materials that can host electrons which split into fractional components of themselves—without the need for a magnetic field, a condition that was previously required for such phenomena.
The phenomenon of electron fractionalization, where electrons break into smaller fractions, was first observed in 1982 and earned its discoverers the Nobel Prize. However, in earlier experiments, a magnetic field was necessary to facilitate this splitting. The 2023 discovery is groundbreaking because it demonstrates that electron fractionalization can occur in the absence of a magnetic field, making the materials hosting these fractionalized electrons more versatile and useful for applications like quantum computing.
The fractions of electrons created in these experiments are known as anyons, a type of quasiparticle that exists only in two-dimensional materials. Anyons are not the typical particles we encounter in daily life—such as electrons or protons—but are instead exotic quasiparticles that can take on different “flavors,” or classes. The 2023 experiments revealed the creation of Abelian anyons, a class of anyons that are less complex than their more exotic cousins, the non-Abelian anyons.
Non-Abelian anyons are of particular interest because they exhibit a unique property: they can “remember” the paths they take through space-time. This memory effect is crucial for quantum computing because it allows for the creation of quantum states that are more robust and resistant to errors. The ability to manipulate these memory-rich non-Abelian anyons could lead to more reliable and powerful quantum computers, capable of performing a broader range of complex tasks.
Liang Fu, a professor at MIT’s Department of Physics and the lead researcher of the study, emphasized that non-Abelian anyons are of immense value in quantum computing due to their potential for quantum memory and error correction. According to Fu, the experiments conducted in 2023 exceeded theoretical expectations, suggesting that future theoretical work in this area should be bolder and more ambitious.
In the study, Fu was joined by graduate students Aidan P. Reddy and Nisarga Paul, and postdoctoral fellow Ahmed Abouelkomsan, all from MIT’s Department of Physics. Reddy and Paul are co-first authors of the paper. The discovery was also highlighted in Physics Magazine, which noted that, if confirmed experimentally, the prediction of non-Abelian anyons could pave the way for quantum computers that are not only more reliable but also more capable of handling a wider range of complex computational tasks. The article further explained that theorists have already proposed methods for using non-Abelian anyons as qubits, and these qubits could enable robust quantum computation.
The discovery was driven by recent advances in the field of two-dimensional (2D) materials, which consist of just one or a few layers of atoms. The fascinating world of 2D materials has unlocked new possibilities for manipulating matter at the quantum level, including stacking and twisting these materials in various ways to create unique properties. These twisted and stacked 2D materials, known as moiré materials, have already led to the discovery of other exotic quantum states.
In the context of this work, the team showed that non-Abelian anyons could potentially form in a specific type of moiré material composed of atomically thin layers of molybdenum ditelluride. The research demonstrated that when electrons are added to this material at densities of 3/2 or 5/2 per unit cell, they can organize into a quantum state that hosts non-Abelian anyons. This opens up new possibilities for creating materials that can support the exotic quantum states required for the next generation of quantum computers.
The results are exciting because the creation of non-Abelian anyons in moiré materials represents an important step forward in understanding and controlling these exotic quantum states. The collaboration involved both concrete numerical calculations and abstract theoretical work, bridging the gap between theory and experiment. Reddy, one of the co-authors, described the process of interpreting their results as challenging but rewarding, highlighting the intricate thought process required to support their findings. Paul, another co-author, noted how the project connected abstract theoretical concepts with tangible calculations, providing a rich learning experience.
Source: Materials Research Laboratory, Massachusetts Institute of Technology