A groundbreaking achievement in quantum computing has been made by a team led by the University of Washington, as they successfully detected fractional quantum anomalous Hall states in semiconductor material flakes. This breakthrough holds great potential for the development of stable and fault-tolerant qubits, a critical component for advancing quantum computers.
The world of computing stands on the cusp of a revolution with quantum technology. Quantum computers have the potential to surpass traditional binary-based machines, found in supercomputers and smartphones, in terms of speed for specific and vital tasks. However, the key challenge lies in building a robust network of qubits capable of storing information, accessing it, and performing computations.
The existing qubit platforms share a common vulnerability – they are fragile and susceptible to external disturbances, even from stray photons. Overcoming this challenge requires the development of fault-tolerant qubits that can withstand such perturbations. The team led by scientists and engineers from the University of Washington has made significant progress in addressing this issue. Their recent studies, published in Nature on June 14 and Science on June 22, reveal the detection of fractional quantum anomalous Hall (FQAH) states in ultra-thin semiconductor material flakes. This discovery represents an important initial step towards constructing fault-tolerant qubits because FQAH states can harbor anyons, peculiar quasiparticles possessing only a fraction of an electron’s charge. Certain types of anyons have the potential to create “topologically protected” qubits, offering stability against localized disturbances.
Xiaodong Xu, the lead researcher responsible for these groundbreaking findings and the Boeing Distinguished Professor of Physics and a professor of materials science and engineering at the University of Washington, remarks, “This really establishes a new paradigm for studying quantum physics with fractional excitations in the future.”
FQAH states are closely related to the fractional quantum Hall state, an exotic phase of matter observed in two-dimensional systems. In these states, electrical conductivity exhibits precise fractional values of the conductance quantum constant. However, conventional fractional quantum Hall systems necessitate the presence of intense magnetic fields to maintain stability, rendering them impractical for quantum computing applications. The FQAH state overcomes this limitation by remaining stable even in the absence of any magnetic field.
To host this extraordinary phase of matter, the researchers constructed an artificial lattice with unique properties. They stacked two atomically thin flakes of a semiconductor material called molybdenum ditelluride (MoTe2) at small twist angles relative to each other, creating a synthetic “honeycomb lattice” for electrons. By cooling the stacked layers to temperatures just above absolute zero, an intrinsic magnetism emerged within the system, eliminating the need for a strong external magnetic field typically associated with the fractional quantum Hall state. Using lasers as probes, the scientists were able to detect distinct characteristics of the FQAH effect, representing a significant advancement towards harnessing the power of anyons for quantum computing.
Collaborating with researchers from the University of Hong Kong, the National Institute for Materials Science in Japan, Boston College, and the Massachusetts Institute of Technology, the team envisions their system as a potent platform for gaining a deeper understanding of anyons, which possess distinct properties compared to ordinary particles like electrons. Anyons are quasiparticles or particle-like “excitations” capable of acting as fractions of an electron. In future experiments using their innovative setup, the researchers aim to explore even more exotic forms of these quasiparticles, known as “non-Abelian” anyons, which could serve as topological qubits. Manipulating non-Abelian anyons through intricate braiding maneuvers allows information to be distributed across the entire system, making it resilient to local disturbances and presenting a significant advancement over current quantum computing capabilities.
Eric Anderson, a physics doctoral student at the University of Washington and lead author of the Science paper and co-lead author of the Nature paper, explains, “This type of topological qubit would be fundamentally different from those that can be created now. The strange behavior of non-Abelian anyons would make them much more robust as a quantum computing platform.”
The emergence of FQAH states in the researchers’ experimental configuration relied on three key properties that coexisted within the system:
- Magnetism: Although MoTe2 is not inherently magnetic, the introduction of positive charges triggered the emergence of a spontaneous spin order, a form of magnetism known as ferromagnetism.
- Topology: The electrical charges within the system exhibited twisted bands, akin to a Möbius strip, contributing to its topological nature.
- Interactions: The charges within the experimental setup interacted with each other strongly enough to stabilize the FQAH state.
The team anticipates that their approach will facilitate the routine investigation and manipulation of these unique FQAH states, accelerating the advancement of quantum computing.
References:
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“Programming correlated magnetic states with gate-controlled moiré geometry” by Eric Anderson et al., Science, June 22, 2023. DOI: 10.1126/science.adg4268
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“Signatures of Fractional Quantum Anomalous Hall States in Twisted MoTe2” by Jiaqi Cai et al., Nature, June 14, 2023. DOI: 10.1038/s41586-023-06289-w
Additional co-authors of the papers include William Holtzmann and Yinong Zhang from the UW Department of Physics, Di Xiao, Chong Wang, Xiaowei Zhang, Xiaoyu Liu, and Ting Cao from the UW Department of Materials Science & Engineering, Feng-Ren Fan and Wang Yao from the University of Hong Kong and the Joint Institute of Theoretical and Computational Physics at Hong Kong, Takashi Taniguchi and Kenji Watanabe from the National Institute of Materials Science in Japan, Ying Ran from Boston College, and Liang Fu from MIT. Funding for this research was provided by the U.S. Department of Energy, the Air Force Office of Scientific Research, the National Science Foundation, the Research Grants Council of Hong Kong, the Croucher Foundation, the Tencent Foundation, the Japan Society for the Promotion of Science, and the University of Washington. Grant numbers include DE-SC0018171, DE-SC0019443, DE-SC0012509, FA9550-19-1-0390, FA9550-21-1-0177, DMR-1719797, DGE-2140004, AoE/P-701/20, HKU SRFS2122-7S05, 19H05790, 20H00354, and 21H05233.
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Frequently Asked Questions (FAQs) about quantum computing breakthrough
What is the significance of detecting fractional quantum anomalous Hall states in semiconductor flakes?
The detection of fractional quantum anomalous Hall (FQAH) states in semiconductor flakes is significant because it represents a major breakthrough in quantum computing. These states could pave the way for the development of stable and fault-tolerant qubits, which are crucial for advancing quantum computers and unlocking their potential for exponential speed and computational power.
How do fractional quantum anomalous Hall states contribute to the creation of stable qubits?
Fractional quantum anomalous Hall (FQAH) states can host anyons, which are unique quasiparticles with only a fraction of an electron’s charge. Certain types of anyons have the potential to create “topologically protected” qubits, which are highly stable and resistant to local disturbances. By utilizing FQAH states and anyons, researchers can work towards developing qubits that can retain information and perform computations reliably, overcoming the vulnerability and fragility of existing qubit platforms.
What are the challenges in developing stable qubits for quantum computing?
One of the main challenges in developing stable qubits for quantum computing is the susceptibility of qubit platforms to external disturbances. Even minor disruptions, such as stray photons, can affect the integrity of qubits and compromise their performance. To enable practical quantum computing, it is crucial to create fault-tolerant qubits that can withstand external perturbations and maintain stable quantum states for prolonged periods.
How did the research team detect fractional quantum anomalous Hall states?
The research team detected fractional quantum anomalous Hall (FQAH) states by conducting experiments with ultra-thin semiconductor material flakes. By stacking atomically thin flakes of a semiconductor material and creating a synthetic “honeycomb lattice” for electrons, they were able to induce an intrinsic magnetism within the system. Using lasers as probes, they detected signatures of the FQAH effect, confirming the presence of FQAH states in their experimental setup.
What potential does the detection of fractional quantum anomalous Hall states hold for quantum computing?
The detection of fractional quantum anomalous Hall (FQAH) states holds great potential for quantum computing. These states could serve as a foundation for developing topologically protected qubits using anyons. Topological qubits are highly robust against local disturbances, making them ideal for quantum computing applications. The discovery of FQAH states opens up new avenues for exploring and manipulating these unique quantum phenomena, accelerating advancements in quantum computing technologies.
More about quantum computing breakthrough
- University of Washington: Research News
- Nature: Signatures of Fractional Quantum Anomalous Hall States in Twisted MoTe2
- Science: Programming correlated magnetic states with gate-controlled moiré geometry
- U.S. Department of Energy: DOE Quantum Information Science Research
- Air Force Office of Scientific Research: Quantum Sciences
- National Science Foundation: Quantum Information Science
- Research Grants Council of Hong Kong: Areas of Excellence Scheme
- Japan Society for the Promotion of Science: Grants-in-Aid for Scientific Research
- University of Washington: Department of Physics
- University of Washington: Department of Materials Science & Engineering
