This PhD project will investigate the experimental characterization and optimization of niobium-based superconducting qubits — a promising platform for scalable quantum computing. Superconducting qubits underpin most current quantum computing architectures, and niobium offers distinct advantages through its higher superconducting gap, enabling operation at higher frequencies and moderately elevated temperatures. These properties open a path toward more scalable systems with improved cooling efficiency and greater integration capability.
Co-funded by Quantcore and the University of Glasgow, the project aims to develop a comprehensive understanding of niobium qubit performance under realistic experimental conditions and its interface with Single Flux Quantum (SFQ) electronics for cryogenic qubit control and readout.
The student will measure and analyse qubit coherence, stability, and noise, using the results to inform the design of improved superconducting circuit architectures optimized for thermal robustness and scalability:
- Performance Benchmarking and Statistical Analysis
Implement randomized benchmarking and process characterization to quantify qubit and gate fidelities. Statistical models will be developed to capture variability across devices and fabrication runs, helping identify performance bottlenecks. - Temperature Stability and Long-Term Fluctuations
Study how coherence times, frequency drift, and relaxation rates vary with temperature, including long-term measurements to reveal slow fluctuations and thermal sensitivities. The work will establish baseline performance metrics for operation above 100 mK, where refrigeration efficiency improves substantially. - Noise Spectroscopy and High-Frequency Operation
Using niobium’s high-frequency capability, the student will perform broadband noise spectroscopy to identify decoherence sources such as flux, charge, and photon noise, supporting the development of mitigation strategies for improved stability. - Single-Shot Readout and High-Rate Data Acquisition
Develop single-shot readout techniques for rapid qubit characterization using FPGA-based control and acquisition systems. These tools will enable detailed statistical studies of noise and drift across large datasets. - Design Feedback for Next-Generation Circuits
Experimental findings will directly inform the design of improved qubit and resonator geometries. Collaboration with Quantcore’s fabrication team will ensure that feedback from measurements translates into practical device enhancements.
As a possible extension, the project may explore the use of Single Flux Quantum (SFQ) circuits for cryogenic qubit control and readout. SFQ electronics, based on quantized voltage pulses in superconducting materials such as niobium, could provide low-power, low-latency control compatible with the cryogenic environment. Investigations may include assessing pulse fidelity, coupling efficiency, and potential noise backaction on qubits.
The student will work in both academic and industrial environments, performing cryogenic and microwave measurements at the University of Glasgow and Quantcore laboratories. Training will include quantum measurement, FPGA programming, data analysis, and circuit modelling, complemented by opportunities to present results at international quantum technology conferences.
The project’s central goal is to enable higher-temperature quantum operation, a key requirement for scaling superconducting processors. Even modest increases in operating temperature can ease cooling demands, allowing more qubits per cryostat and simplifying control integration. The outcomes — a quantitative understanding of niobium qubit performance at elevated temperatures and experimentally guided design improvements — will directly support the development of scalable, energy-efficient superconducting quantum hardware.