Department Colloquium | Exploring and engineering emergent quantum phenomena with diamond spin qubits

Zoom link: https://umich.zoom.us/j/94692610056

A system assembled out of many quantum building blocks can display complex collective behaviors that are unexpected from those of individual elements. Elucidating such emergent quantum phenomena is a frontier science, while engineering and control of these phenomena enable future quantum technologies. Can we gain mastery over emergent quantum phenomena across vastly different scales leading to novel utility? In this talk, I will demonstrate that one can address this question using tools enabled by highly coherent and controllable spin qubits hosted by nitrogen vacancy (NV) centers in diamond. As a top-down approach, quantum sensors realized with NVs provide a powerful tool to unlock emergent phenomena on the macroscopic scales in quantum materials. To illustrate the power of this approach, I will present our results on the discovery of viscous Poiseuille flow of quantum-critical Dirac fluid in graphene [1]. I will also discuss the development of a nanoscale probe of magnons [2] – collective spin excitations – and the study of room-temperature ferromagnetism in 2D magnets [3]. For a bottom-up approach, NV qubits provide a versatile platform to engineer complex quantum phenomena qubit by qubit. To pave the foundation of this effort, we have developed a novel scheme to tune the dipolar coupling between NV qubits via dressed state control [4]. Enabled by these results, I will outline future directions to 1) study emergent phenomena in quantum materials, 2) investigate complex quantum behaviors using diamond quantum simulator, and 3) study emergent properties of magnon-spin qubit hybrid quantum system.

[1] M.J.H. Ku et al., Nature 583, 537 (2020).
[2] H. Zhang, M.J.H. Ku et al., Phys. Rev. B 102, 024404 (2020).
[3] H. Chen et al., arXiv:2110.05314 (2021).
[4] J. Lee, M. Tatsuta, A. Xu, E. Bauch, M.J.H. Ku, and R.L. Walsworth, in preparation (2022)