Creating and studying coherent interactions between disparate solid-state quantum systems is a challenge at the intersection of atomic physics, condensed matter physics, and engineering. In general, different physical realizations of a quantum bit (qubit) operate at different frequencies, on different size scales, and couple to different fields. Nonetheless, efforts to create “hybrid quantum systems” are appealing because they could enable a quantum concert – were parts are played by different physical qubits that each offer the best performance in a particular area. There is a growing consensus that mechanical motion is a “plastic” degree of freedom for solid-state qubits, with the potential to form a coherent interface between them, and with light. This has motivated intense research into the coherent interactions between mechanical resonators and qubits formed from photons, trapped atoms, superconducting circuits, quantum dots, and nitrogen-vacancy (NV) centers in diamond, to name a few. I will describe our experiments to coherently couple NV center spins to gigahertz-frequency mechanical resonators using crystal lattice strain. In high-quality diamond mechanical resonators, we demonstrate coherent Rabi oscillations of NV center spins driven by mechanical motion instead of an oscillating magnetic field. We also use the mechanical resonator to protect the coherence of the NV center spin. Finally, I will describe recent results in which we experimentally examine the spin-strain coupling within the NV center excited-state manifold and explain how it can be used to cool a mechanical mode.

After teaching high school physics and chemistry for five years, Fuchs enrolled at Cornell University in 2001, earning his Ph.D. in Applied Physics in 2007. Afterward, he moved to the University of California, Santa Barbara as a postdoctoral associate. In 2011, he joined the Cornell faculty of Applied and Engineering Physics. In 2012 he received a Young Investigator Award from the Air Force Office of Scientific Research, in 2013 he received both an Early Faculty Career Award from the National Science Foundation and the Presidential Early Career Award for Scientists and Engineers sponsored by the Department of Defense. In 2014 he received the Early Career Award from the Department of Energy. Fuchs’ research group focuses on understanding and using solid-state controls for semiconductor defect-based qubits and quantum emitters. His group is also interested in spintronics, for which they recently invented a spatiotemporal magnetic microscope that uses heat instead of light to probe spin dynamics at the nanoscale.

Department of Physics and Astronomy Condensed Matter Seminar Series, Purdue Quantum Center

Researchers should cite this work as follows:

• E. R. MacQuarrie, T. A. Gosavi, N. R. Jungwirth, S. A. Bhave, and G. D. Fuchs, "Mechanical spin control of nitrogen-vacancy centers in diamond," Phys. Rev. Lett. 111, 227602 (2013).

  E. R. MacQuarrie, T. A. Gosavi, A. M. Moehle, N. R. Jungwirth, S. A. Bhave, and G. D. Fuchs, "Coherent Control of a Nitrogen-Vacancy Center Spin Ensemble with a Diamond Mechanical Resonator." Optica, 2, 233 (2015).

  E. R. MacQuarrie, T. A. Gosavi, S. A. Bhave, and G. D. Fuchs, "Continuous dynamical decoupling of a single diamond nitrogen-vacancy center spin with a mechanical resonator." Phys. Rev. B 92, 224419 (2015).

  E. R. MacQuarrie, M. Otten, S. K. Gray, and G. D. Fuchs, "Cooling a mechanical resonator with nitrogen-vacancy centres using a room temperature excited state spin-strain interaction," Nature Communications 8, 14358 (2017).

• Gregory David Fuchs (2018), "Quantum Control Over Diamond Spins with a Mechanical Resonator," https://nanohub.org/resources/27830.

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1. NV diamonds
2. quantum science and information
3. quantum systems
4. qubits