Hannah Stern

Prior to being recruited to Oxford as an Associate Professor in Materials Science and Trinity College as a Tutorial Fellow, I was a Lecturer at the Photon Science Institute, University of Manchester and a Royal Society Fellow at the Cavendish Laboratory, University of Cambridge. I did my undergraduate in Chemistry at Otago University in New Zealand and completed my PhD in Physics at the University of Cambridge (2013-2017), before gaining a Junior Research Fellowship at Trinity College, Cambridge which I held until 2021. In 2022 I was awarded a Royal Society University Research Fellowship. 

My research interests lie in the fundamental photophysical properties of materials and how we can harness these properties in nanoscale devices. In particular, my expertise is in probing excitations in materials with spin, and understanding how we can control and use this spin for spin qubits in quantum devices or exciton multiplication in solar cells. 

As a Tutorial Fellow in Materials at Trinity, I deliver tutorials to all Trinity undergraduates studying for their Materials MEng degree. I also run an active research group where I supervise Part II undergraduate (4^th year research students) and DPhil students.

My research group pioneers new material systems for optical technologies, including quantum and renewable energy technologies. We study materials where the quantum mechanical description of their photoexcited states is critical to their application in devices. Our recent work is based on understanding atomic scale point defects in two-dimensional materials, and how the spin states formed upon optical excitation can be used to form next-generation quantum devices, such as repeaters that can distribute quantum entanglement across a global network, or sensors that can probe magnetic and electric fields with nanometre-scale resolution. 

We ask the following questions: how does the atomic structure, symmetry, vibrations and environmental conditions of defects, or molecules, affect the excited state dynamics? What limits the spin and optical coherence of these systems? Can we design atomic-scale quantum systems from bottom up that have near-ideal optical and spin properties for scalable quantum devices?

As a largely experimental group, we use a combination of spectroscopic, microscopic and materials characterisation tools, including optical confocal microscopy, time-resolved spectroscopy, electron microscopy and optically detected magnetic resonance. These tools allow us to study and control systems on the single particle level, ie. optically control of single electronic and nuclear spins, and detection of single photon emission. Using university cleanrooms, we design and incorporate the systems we study into devices. 

While fundamental in nature, we are motivated by the direct application of our research to emerging technologies and the potential it may have to increase industrial productivity. To date, our research has contributed to the design of organic solar cells, as well as design of future room-temperature quantum devices for nanoscale sensing and networks, based on two-dimensional materials. The research has resulted in two patents, one spin-off company and we are actively involved with ongoing commercialisation initiatives. 

C. M. Gilardoni, S. Eizagirre Barker, C. L. Curtin, S. A. Fraser, O. F.J. Powell, D. K. Lewis, X. Deng, A. J. Ramsay, C. Li, I. Aharonovich, H. H. Tan, M.Atatüre and H. L. Stern. ‘ A single spin in hexagonal boron nitride for vectorial quantum magnetometry’. arXiv.:2408.10348 (2024).

H.L Stern*, C. M. Gilardoni*, Q. Gu, S. Eizagirre Barker, O. Powell, X. Deng, L. Follet, C. Li, A. Ramsey, H. H. Tan, I. Aharonovich and M. Atatüre. ‘ A quantum coherent spin in hexagonal boron nitride at room temperature.’ Nature Materials, (2024).

H.L Stern*, Q. Gu *, J. Jarman*, S. Eizagirre Barker, N. Mendelson, D. Chugh, S. Schott, H. H. Tan, H. Sirringhaus, I. Aharonovich and M. Atatüre. ‘Room-temperature optically detected magnetic resonance of single defects in hexagonal boron nitride.’ Nature Communications, 13, 681, (2022).

H.L. Stern, R. Wang, R. Mizuta, J.C. Stewart, T. D. Roberts, R. Wai, N. S. Ginsberg, D. Klenerman, S. Hofmann and S. Lee. 'Spectrally-resolved photodynamics of individual emitters in large-area monolayers of hexagonal boron nitride.’ ACS Nano, 13, 4538-4547, (2019).

H.L Stern, A. Cheminal, S. R Yost, K. Broch, S.L. Bayliss, K. Chen, M. Tabachyk, K. Thorley, N. Greenham, J. M Hodgkiss, J. Anthony, M. Head-Gordon, A.J Musser, A. Rao and R. H. Friend. ‘Vibronically coherent ultrafast triplet-pair formation and subsequent thermally activated dissociation control efficient endothermic singlet fission.’ Nature Chemistry, 9, 1205-1212 (2017). 

H.L. Stern, A.J. Musser, S. Gelinas, P. Parkinson, L. M. Herz, M. J. Bruzek, J. Anthony, R. H. Friend, and B.J. Walker. ‘Identification of a triplet pair intermediate in singlet exciton fission in solution.’ PNAS,  111, 25 (2015).