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Dr. Christoph Boehme, September 23

Spin-based Quantum Sensing with Charge Carrier Spin States in Organic Semiconductors

Abstract:

Quantum sensors probe physical observables by utilizing the inherent volatility of quantum states due to interaction with their environment. Quantum sensors can overcome the sensitivity limits of classical sensors, and they can also probe inherently quantum mechanical observables such as entanglement and permutation symmetry; This presentation is about quantum sensing concepts based on electron spin states in organic condensed matter environments. Due to weak spin-orbit coupling, paramagnetic charge carrier states in π-conjugated polymer thin films are subject to pronounced spin selection rules and, also, they exhibit spin coherence times in the order of a ms, limited only by unresolved proton hyperfine fields caused by the all-abundant hydrogen in these materials. The spin-selection rules enable straightforward electrical detection of coherent propagation of these spin states [1]. We have utilized these as spin-based quantum sensors [2] for the study of the non-perturbative drive regime of magnetic dipole excitations. These experiments have revealed previously not accessible magnetic resonant strong-drive phenomena, including spin-collectivity effects [3], multiple-quantum transitions occurring at integer and fractional g-factors, as well as a magnetic resonant Bloch-Siegert Shift [4,5].

[1] D.R. McCamey et al., Phys. Rev. Lett. 104 (1), 017601; [2] W. J. Baker et al., Nature Commun. 3, 898, (2012); [3] D. P. Waters et al., Nat. Phys., 11, 910 (2015); [4] S. Jamali et al., Nano Lett. 17, 4648 (2017); [5] S. Jamali et al., Nature Commun. 12 (1), 1 (2021).

Biography:

Professor Christoph Boehme is an internationally known expert on spin-related electronic materials. He received his Dipl. Physi. at Ruprecht-Karls-Universität, Heidelberg, M.Sc. at North Carolina State University, Ph.D at  University of Marburg in 2002. After Ph.D, Dr. Boehme conducted his postdoctoral research at Hahn-Meitner Institut, a national laboratory, Berlin, Germany. He moved to University of Utah in 2006 to join the Department of Physics & Astronomy as an Assistant Professor. He was promoted into the rank of Associate Professor and awarded tenure in 2010, promoted to the rank of Professor in 2013.  Dr. Boehme was appointed as interim departmental chair in 2019 and departmental chair in 2020 in the Department of Physics & Astronomy, University of Utah. Dr. Boehme has been conducting multidisciplinary research with broad topics including spin-dependent processes in organic semiconductors, spin-dependent electronic transitions in silicon-related materials, spin current and inverse spin-Hall effects, theoretical development of electrically and optically detected magnetic resonance (EDMR & ODMR) schemes, and spin spectroscopy for investigating electronically active defects.