Summary: UCLA researchers in the Department of Electrical Engineering have developed a superconducting diode-based nonreciprocal interconnect that enables low-loss, directional microwave signal routing between qubits, chips, and cryogenic modules while preserving quantum coherence and suppressing back-propagating noise.
Background: Scalable superconducting quantum processors require low-loss, high-fidelity interconnects for signal routing between qubits, chips, and distributed cryogenic modules. Conventional microwave interconnects are reciprocal, allowing back-propagating noise, crosstalk, and spurious excitations to travel between subsystems, degrading qubit coherence, entanglement fidelity, and gate performance. Existing nonreciprocal solutions, such as ferrite-based circulators, insulators, and active microwave switching networks, rely on magnetic biasing, exhibit insertion loss, and are bulky and difficult to integrate within cryogenic and magnetically-sensitive superconducting environments. Further, their size, power requirements, and limited scalability make them unsuitable for densely integrated quantum architectures. Thus, there is an unmet need for a compact, low-loss, fully superconducting, and intrinsically directional interconnect that can provide on-chip and inter-module isolation while preserving quantum coherence in large-scale superconducting quantum systems.
Innovation: Professor Pri Narang and her research team have developed a superconducting diode (SD)-based coupler that enables intrinsically nonreciprocal microwave transmission between qubits, chips, and cryostat-separated modules. Implemented as a fully superconducting, passive interconnect, the SD enables low forward impedance and high transmission to preserve quantum coherence and support high-fidelity state transfer and entanglement distribution. Its high reverse impedance simultaneously suppresses back-propagating noise, crosstalk, and spurious excitations, protecting idle qubits and reducing correlated errors. Unlike ferrite-based or actively biased nonreciprocal components, the proposed design is compact, magnet-free, low-loss, and directly compatible with scalable superconducting circuit integration, representing a significant advancement in directional quantum interconnects.
Potential Applications: ● Superconducting quantum processors ● Modular and distributed quantum computing ● Qubit and chip interconnects ● Cryogenic quantum networking ● Quantum measurement and control systems
Advantages: ● No external isolators or circulators ● Low-loss superconducting operation ● High fidelity and entanglement success probability ● Compact, chip-integrated form factor ● Passive, bias-free design ● Scalable quantum system integration
State of Development: First description of complete invention: August 2025
Related Publications: Dirnegger, Nicolas, et al. "Nonreciprocal Quantum Information Processing with Superconducting Diodes in Circuit Quantum Electrodynamics." arXiv, 25 Nov. 2025, https://doi.org/10.48550/arXiv.2511.20758.
Reference: UCLA Case No. 2026-078
Lead Inventor: Professor Prineha Narang