A newly developed superconductor material that may find applications in quantum computing and could be a candidate for a “topological superconductor” has been produced by a collaborative team of scientists across multiple institutions in the United States, spearheaded by physicist Peng Wei at the University of California, Riverside.
Topology refers to the mathematics of shape. A topological superconductor utilizes a delocalized state of either an electron or a hole (a hole acts as an electron with a positive charge) to transmit quantum information and execute data processing in a durable manner.
Chiral Material and Interface Superconductivity
The researchers have reported today (August 23) in Science Advances that they have fused trigonal tellurium with a surface state superconductor created at the surface of a thin film of gold. Trigonal tellurium is a chiral material, meaning it cannot be superimposed on its mirror image, akin to our left and right hands. Trigonal tellurium is also non-magnetic. However, the researchers identified quantum states at the interface that possess well-defined spin polarization. This spin polarization enables the excitations to potentially function in the creation of a spin quantum bit — or qubit.
Spin Polarization and Qubit Potential
“By establishing an extremely clean interface between the chiral material and gold, we constructed a two-dimensional interface superconductor,” stated Wei, an associate professor of physics and astronomy. “The interface superconductor is distinctive as it exists in an environment where the energy of the spin is six times more amplified than in conventional superconductors.”
The researchers noted that the interface superconductor experiences a transition under a magnetic field, becoming more resilient at high fields compared to lower ones, indicating a transition into a “triplet superconductor,” which is more robust under a magnetic field.
Mitigating Decoherence in Quantum Computing
Moreover, through partnership with scientists at the National Institute of Standards and Technology (NIST), the researchers demonstrated that such a superconductor comprising heterostructure gold and niobium thin films inherently suppresses decoherence sources from material imperfections, such as niobium oxides, which present a frequent challenge for niobium superconductors. They illustrated that the superconductor can be fashioned into high-quality low-loss microwave resonators, achieving a quality factor of up to 1 million.
Implications for Quantum Computing Technology
The innovative technology holds potential applications in quantum computing, a domain that exploits quantum mechanics to address complex issues that classical computers or supercomputers cannot solve or cannot resolve promptly enough, as stated by the multinational technology corporation IBM.
“We accomplished this employing materials that are an order of magnitude thinner than those conventionally utilized in the quantum computing sector,” Wei mentioned. “The low-loss microwave resonators are vital components for quantum computing and could pave the way for low-loss superconducting qubits. The principal challenge in quantum computing is to minimize decoherence or the loss of quantum information within a qubit system.”
Decoherence transpires when a quantum system interacts with its surroundings, leading to the system’s information becoming entangled with the environment. Decoherence presents a significant obstacle to the realization of quantum computers.
In contrast to prior methods necessitating magnetic materials, the researchers’ novel strategy employs non-magnetic materials for a cleaner interface.
A Bright Future for Scalable Quantum Components
“Our material could serve as a promising contender for the advancement of more scalable and reliable quantum computing components,” Wei remarked.
Reference: “Signatures of a Spin-Active Interface and Locally Enhanced Zeeman Field in a Superconductor-Chiral Material Heterostructure” 23 August 2024, Science Advances.
DOI: 10.1126/sciadv.ado4875
Wei was accompanied in the research by his graduate students at UCR.
The UCR’s involvement in the research initiative was financed by Wei’s NSF CAREER award, a NSF Convergence Accelerator Track-C grant jointly held by UCR and MIT, and a Lincoln Lab Line fund shared by UCR and MIT.
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