Bio

Holly Stemp is a Postdoctoral Associate at the Massachusetts Institute of Technology, working with Prof. William Oliver in the Engineering Quantum Systems group. In this role she is focused on implementing hybrid spin/superconducting qubit architectures. Holly carried out her PhD with Prof. Andrea Morello at the University of New South Wales in Sydney, Australia, where her project consisted of characterizing multi-qubit operations in a system of two exchange-coupled donor spin qubits. For her PhD thesis Holly was awarded the 2025 Malcolm Chaikin Prize for Research Excellence in Engineering, recognizing the best thesis in the UNSW Engineering faculty for that year. Prior to that, she carried out a master’s degree in physics at the University of Surrey in the UK. As part of her master’s degree she spent 10 months working at Oak Ridge National Laboratory in Tennessee, USA in both the department of nuclear astrophysics and quantum computing.

Long-range entanglement of quantum dot spin qubits mediated by a superconducting qubit coupler

Quantum computing is set to revolutionize the way that we approach certain computational problems facing humanity today. One promising candidate for the fundamental building blocks of a quantum computer are electron spins confined in quantum dots. A key advantage of quantum dots is their small physical footprint, which enables the integration of many millions of qubits, quantum computing bits, on a single chip. However, this high qubit density creates challenges in routing the on-chip classical control electronics needed to scale these systems to a size capable of solving problems of real-world relevance. To address this, long-range spin coupling mechanisms are needed, to connect spatially sparse arrays of spin qubits. While previous approaches have explored spin shuttling and coupling to superconducting resonators for this purpose, both present their own advantages and challenges. In my work I am implementing an alternative coupling scheme that instead utilizes a superconducting qubit as an intermediate coupling mechanism between quantum dots. This coupling scheme is fast and removes the need for high impedance resonators, which are a large source of loss in these systems.

One important aspect of my research is developing a measurement infrastructure that is capable of simultaneously operating high fidelity quantum dot and superconducting qubits, which both possess their own unique requirements. Our approach aims to establish engineering best practices for operating scalable, hybrid superconductor-semiconductor quantum processors.