CAREER: Advancing modular quantum computing with Josephson junction field effect transistors

About This Grant

Quantum computers promise capabilities far beyond those of today’s classical machines, with potential applications in areas such as materials discovery, secure communication, and advanced sensing. However, existing quantum processors face major engineering barriers to continued progress. Present day superconducting quantum processors are built as single, monolithic chips in which all quantum bits (qubits) reside on a single substrate. As systems grow, this architecture becomes increasingly fragile: crosstalk rises, wiring becomes unmanageable, and a single faulty component can compromise the entire processor. As a result, the monolithic approach cannot be scaled to the chip sizes or wiring densities required for future fault-tolerant machines. A promising alternative is a modular architecture in which many smaller, high quality quantum chips are interconnected to create a larger and more capable system. Realizing such modular systems requires new technologies for routing extremely weak microwave signals between chips without disturbing their delicate quantum states. This CAREER project will develop such a technology using a hybrid superconductor–semiconductor component known as the Josephson Junction Field Effect Transistor (JJFET). The JJFET marries the low loss, coherence preserving properties of superconductors with the voltage tunable control and nanoscale footprint of semiconductor transistors, enabling compact, efficient, and reconfigurable routers that can connect quantum chips on demand. Success in this project will provide a key architectural building block for scaling up future quantum computers. In parallel, the project integrates hands on training for graduate, undergraduate, and K–12 students, strengthening the nation’s quantum ready STEM workforce and broadening public engagement with emerging quantum technologies. Technically, the project will establish JJFETs as voltage controlled superconducting elements capable of routing single photon microwave signals between separate quantum modules with high speed, low loss, and low crosstalk. By leveraging a high transparency superconductor–semiconductor interface, the JJFET provides a gate tunable Josephson inductance that enables transistor like control of quantum microwave signals while preserving coherence. The research program will develop and characterize a suite of JJFET based microwave components, beginning with single pole switches optimized for switching speed, power dissipation and microwave loss. Building on this foundation, the project will demonstrate on demand routing of microwave photons between physically separated transmon qubits, with remote entanglement serving as a sensitive probe of routing fidelity and system level performance. The final phase will realize a multiport JJFET based transfer switch that provides dynamically configurable communication pathways for modular quantum processors. By replacing bulky, magnetic flux controlled circuitry with compact, voltage controlled elements compatible with semiconductor style scaling, the JJFET platform introduces a fundamentally new approach to designing routers for signals between quantum chips. This technology opens the door to dense integration of routing and signal processing elements, supports emerging quantum network architectures, and establishes a scalable framework for building the next generation of modular quantum information systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.