Coherent Control of an NV- center and a nearby 13C nuclear spin

David Levonian, Michael Goldman, Swati Singh +3 more

Johannes Lang, Christian Osterkamp, Christoph Findler +1 more

The nitrogen-vacancy (NV) center in diamond is a promising candidate for development of quantum communication and simulation devices which are based on the control of coupled quantum systems. It offers an optical readout of its spin state, exhibits long coherence times and allows to coherently control nearby nuclear spins, e.g. from 13C nuclei, even at room-temperature. For successful demonstration of such systems however, controlling the nuclear spin environment, and thus tuning the coupling strengths is crucial to allow the fabrication of a scalable platforms. The combination of Chemical Vapor Deposition (CVD) of diamond as a method with isotopic control on the diamond composition and ion implantation as a tool to reliably create NV centers is a perfect toolkit to study the realization such quantum systems.

Takaaki Shimo-Oka, Hiromitsu Kato, Satoshi Yamasaki +4 more

Individual nuclear spins in diamond can be optically detected through hyperfine couplings with the electron spin of a single nitrogen-vacancy (NV) center; such nuclear spins have outstandingly long coherence times. Among the hyperfine couplings in the NV center, the nearest neighbor 13C nuclear spins have the largest coupling strength. Nearest neighbor 13C nuclear spins have the potential to perform fastest gate operations, providing highest fidelity in quantum computing. Herein, we report on the control of coherences in the NV center where all three nearest neighbor carbons are of the 13C isotope. Coherence among the three and four qubits are generated and analyzed at room temperature.

Mo Chen, Won Kyu Calvin Sun, Jean-Christophe Jaskula +2 more

Maxwell D. Aiello, Janis Smits, Yaser Silani +13 more

Precision measurements based on optically detected nuclear magnetic resonance offer exquisite sensitivity to absolute shifts in spin transition frequencies, with potential applications in fundamental physics experiments and inertial sensing. We investigate 13C nuclear spins in diamond as a candidate system for solid-state implementations, which hold the promise for high-fidelity readout of large numbers of coherent nuclear spins in millitesla or lower magnetic fields. We demonstrate a technique that allows for both optical polarization and readout of large ensembles of ~10^{16} polarized nuclear spins. Our method takes advantage of state-selective Landau-Zener transitions under microwave frequency sweeping, which bidirectionally transfer spin polarization between Nitrogen-Vacancy (NV) electron spins and remote 13C nuclear spins. Using natural isotopic abundance diamonds with nitrogen densities of ~0.5-10 ppm, we perform optically-detected 13C Ramsey spectroscopy and realize a nuclear-spin-dependent fluorescence contrast exceeding 0.5% peak-to-peak. We observe nuclear spin dephasing times T2*~2 ms that only modestly improve with homonuclear dipolar decoupling, indicating that they are limited by the longitudinal spin relaxation of nearby NV electron spins. We study the magnetic field dependence of the optical readout and find comparable contrast and dephasing times for magnetic fields in the range 8-20 mT. Our method can be interpreted as a type of repetitive readout, where each NV center optically reads out the spin state of ~10^2 nuclei before nuclear spins depolarize.

Yusuke Azuma, Hideyuki Watanabe, Satoshi Kashiwaya +1 more