Phase-controlled coherent dynamics of a single spin under closed-contour interaction

Arne Barfuss, Johannes Koelbl, Lucas Thiel, Jean Teissier, Mark Kasperczyk, Patrick Maletinsky
Department of Physics, University of Basel, Switzerland

The Nitrogen-Vacancy (NV) center in diamond has long been a useful testbed for quantum optics and quantum information processing because its state can be optically prepared and read out, and it exhibits long coherence times even at room temperature. Our system is a single NV center in a diamond cantilever, in which we study the coupling between the strain of the cantilever and the NV spin. We use the three levels of the NV ground state spin triplet to form a closed-contour interaction (CCI) scheme, such that we address each of the three possible transitions with coherent driving fields. Two of the transitions are driven by microwave fields, and the third (magnetic dipole-forbidden transition) is driven by strain through mechanical excitation of the cantilever. We explore the effects of the relative phases of the driving fields on the population dynamics of the NV, showing coherent control of the population, as well as significantly extended coherence times. We further explore novel techniques to prepare our NV in the dressed states of the driving fields. Our results suggest novel applications in magnetic field sensing and quantum state preparation.

[1] A. Barfuss, J. Koelbl, L. Thiel, J. Teissier, M. Kasperczyk, and P. Maletinsky, arXiv:1802.04824 (2018)