Researchers at the Co-design Center for Quantum Advantage (C2QA), a DOE National Quantum Information Science Research Center led by Brookhaven Lab, have successfully demonstrated a qubit design that shows promise for mass production while maintaining comparable performance to current industry-standard qubits.
Through a series of mathematical analyses, scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have developed guidelines for producing qubits more efficiently, ensuring their reliability and strength in quantum computing systems.
One of the key focuses of recent research has been on improving the coherence of qubits, which is crucial for maintaining quantum information integrity. This coherence is heavily influenced by the quality of the qubit’s junction.
The primary focus has been on superconducting qubits, which utilize an SIS junction (superconductor-insulator-superconductor) design. However, manufacturing these junctions with the precision required for mass production has proven to be a significant challenge.
In a recent study, researchers investigated the potential performance tradeoffs of transitioning from SIS junctions to constriction junctions, aiming to understand the impact of this architectural change.
While traditional superconducting qubits rely on SIS junctions that limit current flow, researchers found that constriction junctions, which typically allow more current, could still be effective for qubits. By utilizing less conventional superconducting metals, it was possible to achieve suitable current levels for superconducting qubits.
However, constriction junctions operate differently from SIS junctions, prompting scientists to explore the effects of this design change on qubit functionality.
For superconducting qubits to operate effectively, they require nonlinearity to function between two energy levels. While superconductors do not naturally exhibit this nonlinearity, it is introduced through the qubit junction.
Researchers found that constriction junctions, being more linear than traditional SIS junctions, could be better suited for qubit designs. By carefully selecting superconducting materials and optimizing the junction’s size and shape, researchers were able to adjust the nonlinearity of constriction junctions to meet qubit requirements.
This research provides valuable insights for materials scientists, guiding them towards specific material characteristics based on device requirements.
Researchers are now exploring superconducting transition metal silicides as potential materials that meet the outlined criteria, offering a simpler fabrication process for qubits with constriction junctions.
This study aligns with C2QA’s co-design principle, as researchers aim to develop a qubit architecture that meets the demands of quantum computing while leveraging existing electronics manufacturing capabilities.
Journal Reference:
- Mingzhao Liu (刘é“é’Š) and Charles T. Black. Performance analysis of superconductor-constriction-superconductor transmon qubits. Phys. Rev. A. DOI: 10.1103/PhysRevA.110.012427
