Harnessing spin in molecular systems

Quantum mechanics - our best fundamental theory of atoms and molecules - presents several remarkable properties which if harnessed would generate major scientific and technological breakthroughs. For example: quantum particles, such as electrons, have an intrinsic property called spin which has no direct analogy to our usual notions of rotation; these spins can exist in multiple orientations at the same time (a superposition state); and they can be entangled such that physically separated particles must be described as a composite entity. My research seeks to understand and deploy these spin states in chemically synthesised molecules, with applications in two broad themes:

1. Molecular spins for quantum sensing.

The sensitivity of spin states to their environment makes them promising sensors for a range of properties including magnetic and electric fields, strain, and temperature. This spin-based sensing approach offers exciting applications ranging from thermometry inside biological cells to nanoscale imaging of new phases of matter. Molecular systems could potentially revolutionise quantum sensing through their unique combination of properties: they can be chemically tuned to match a specific sensing target, self-assembled into multi-spin structures for applications ranging from entanglement-enhanced sensing to wide-field imaging, and readily brought close to a sensing target due to their nanoscale, self-contained nature. However, a foundational understanding of how to harness such molecular spin systems is needed.

My research seeks to address this challenge by studying the interface of molecular spins with external stimuli such as light, strain, temperature, and electric fields, and controlling molecular spin superpositions and entanglement. Key aims include: demonstrating a spin-based sensor in an organic molecule, achieving room temperature sensor readout with light, efficiently coupling molecular spins to strain and thermal fields, and generating entanglement among single spins. From these fundamental insights, a broad class of tailor-made molecular quantum sensors could be realised, with implications for understanding both physics and biology.

2. Spins in molecular materials and devices.

In addition to being a powerful resource for quantum sensing, spin also offers a native nanoscale window into the function of molecular devices, such as next-generation light-emitting diodes and solar cells. These systems naturally generate long-lived spin states, offering a sensitive intrinsic means to map structure and dynamics down to nanometre length scales that would otherwise be extremely challenging to access. This spin-based window provides a means to unravel phenomena ranging from light harvesting and photocatalysis to light emission and charge recombination, understand the role of spin-dependent processes on device performance, and ultimately aid deterministic design of future molecular devices.

As a second complementary research theme, I will use spin as a native probe to understand the microscopic processes behind next-generation light-emitting and light-harvesting materials. Using spin-sensitive methods down to the ultimate limit of single molecules, I aim to provide unprecedented insight into these photophysical phenomena, and the foundations from which novel optoelectronic devices can be constructed.

By focusing on two conventionally distinct but symbiotic themes of quantum sensing and optoelectronic materials, I aim to cross-pollinate these fields: the quantum sensing theme will provide new approaches to understand next-generation optoelectronic devices, while the molecular devices theme will provide new materials and architectures that could be utilised for quantum sensing. Overall, these efforts will lead to new possibilities for quantum-engineered molecular materials and devices.