Superconducting device develops continuous-variable quantum computing

Researchers at Universidade Federal de São Carlos (UFSCar) in Brazil have developed a building block for quantum computing utilizing continuous-variable computation. Published August 13, 2026, in Quantum Science and Technology with DOI 10.1088/2058-9565/ae9187, the work details a superconducting device exploring an approach that differs from more common qubit-based systems. This continuous-variable method exploits the infinite-dimensional Hilbert space of bosonic modes, potentially offering a distinct path toward scalable and universal quantum computation. The authors report that the system achieves high fidelities within current parameter ranges.

This two-layer system utilizes a DC-SQUID as the foundational bosonic mode, circumventing limitations found in existing superconducting platforms and offering a different approach to scalability. The work demonstrates high fidelities across all gates within achievable experimental parameters, a crucial step toward practical continuous-variable quantum computers. The architecture integrates a fluxonium qubit to mediate nonlinear interactions essential for quantum processing, alongside two ancillary qubits that facilitate both Gaussian and multi-mode operations.

By precisely tuning applied fluxes and frequencies, the team achieved control over rotation, displacement, squeezing, Kerr interactions, and beam splitting, the five gates comprising a universal continuous-variable set. This level of control is significant because it allows for the implementation of any quantum algorithm within the continuous-variable framework, which differs from the more common qubit-based approach. The researchers report that the modular design of the system is intended to allow for scaling to more complex circuits.

This development addresses a key challenge in superconducting quantum computing; while superconducting qubits have shown promise, realizing universal continuous-variable computation has remained elusive. The team’s simulation indicates that the system operates within current parameter ranges, suggesting a viable path toward physical realization. The study’s data and numerical codes are available upon request, facilitating further investigation and replication of the results. The published work establishes “a feasible pathway toward high-fidelity, universal continuous-variable quantum computation based on superconducting circuits,” potentially broadening the possibilities for quantum computing technologies.