PhD: Unravelling the origin of decoherence in superconducting quantum devices from two-level s

About the Role

Quantum computers, computers which leverage the laws of quantum mechanics to solve certain problems far more efficiently than classical computers, has the promise of revolutionising the fields of cybersecurity, optimisation, drug discovery, clean energy, and data management and searching, among others. Unfortunately, realising this promise of quantum computing has been challenging because quantum states in these computers are extremely fragile and can decohere before any practical problem can be solved. For superconducting quantum bits (qubits)—one of the most mature and widely used quantum computing platforms—a dominant source of decoherence arises from microscopic material defects known as two-level system (TLS) defects. Surprisingly little is known about them, including where they reside in the device and how they form. To address this challenge, the Quantum Technologies Department at the UK’s National Physical Laboratory (NPL) is developing the Scanning Quantum Probe Microscope (SQPM). The first of its kind in the world, the SQPM is based on the atomic force microscope and operates under the same stringent conditions as superconducting qubits – at mK temperatures, inside a light-tight dilution refrigerator. A recent proof-of-principle has demonstrated its ability to detect TLS defects, enabling unprecedented studies of their properties.

The aim is to study material defects and understand their dissipation mechanisms in superconducting quantum devices. The aim is then to also connect them with structural information that can be obtained with other (high-throughput) materials science techniques. For example, devices, thin films and interfaces will be studied by x-ray scattering in the X-ray Laboratory at Royal Holloway. Other local probes such as tip-enhanced Raman scattering (TERS) and scanning near-field optical microscopy (SNOM) will also be explored to infer chemical properties of the defects located in the SQPM.

About You

We are seeking a motivated PhD student with an undergraduate degree in Physics or a related discipline, and a strong interest in experimental research and instrument development.

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About Us

The National Physical Laboratory (NPL) is a world-leading centre of excellence that provides cutting-edge measurement science, engineering and technology to underpin prosperity and quality of life in the UK. Find out more about what it is like working here - The measure of us - Overview