Molecules for Quantum Technologies

Quantum technologies are set to change the world we live in in many more ways than one. Immense advances have been made, but potential show-stoppers, especially concerning scalability, loom on the horizon. Therefore, the search for an alternative quantum technological platform is on. Molecular quantum bits are the basis for such an alternative platform, because they are highly scalable, tunable and positionable. Coherence times have been shown by ourselves and others to be competitive with other quantum technological platforms.^1-3 Current challenges in the field are individual readout and device integration.<br/>Here we present our past and recent advances in this area. First, we have immobilized molecular qubits in self-assembled monolayers on surfaces. We have conclusively proven monolayer formation. We have demonstrated quantum coherence in the immobilized qubits, which is an essential step towards device integration.⁴ Secondly, we have developed hybrid materials of molecular qubits with semiconducting polymers. We have shown by organic field-effect transistor measurements that the electrical properties of the polymers are unimpeded by the incorporation of the quantum bits. Furthermore, the embedded molecular qubits were shown to still possess long coherence times, even in the presence of mobile charge carriers.⁵ These are important steps on the way to electrical readout of (individual) molecular quantum bis in spintronic devices.<br/><br/>(1) Bader, K.; Dengler, D.; Lenz, S.; Endeward, B.; Jiang, S.-D.; Neugebauer, P.; van Slageren, J. <i>Nat. Commun.</i> <b>2014</b>, <i>5</i>, 5304.<br/>(2) Schäfter, D.; Wischnat, J.; Tesi, L.; De Sousa, J. A.; Little, E.; McGuire, J.; Mas-Torrent, M.; Rovira, C.; Veciana, J.; Tuna, F.; Crivillers, N.; van Slageren, J. <i>Adv. Mater.</i> <b>2023</b>, <i>35</i>, 2302114.<br/>(3) Zadrozny, J. M.; Niklas, J.; Poluektov, O. G.; Freedman, D. E. <i>ACS Cent. Sci.</i> <b>2015</b>, <i>1</i>, 488.<br/>(4) Tesi, L.; Stemmler, F.; Winkler, M.; Liu, S. S. Y.; Das, S.; Sun, X.; Zharnikov, M.; Ludwigs, S.; van Slageren, J. <i>Adv. Mater.</i> <b>2023</b>, <i>35</i>, 2208998.<br/>(5) Kern, M.; Tesi, L.; Neusser, D.; Rußegger, N.; Winkler, M.; Allgaier, A.; Gross, Y. M.; Bechler, S.; Funk, H. S.; Chang, L.-T.; Schulze, J.; Ludwigs, S.; van Slageren, J. <i>Adv. Funct. Mater.</i> <b>2021</b>, <i>31</i>, 2006882.