We demonstrate highly-tunable formation of nitrogen-vacancy (NV) centers using 20 keV 15 N + ion implantation through arrays of high-resolution apertures fabricated with electron beam lithography. By varying the aperture diameters from 80 to 240 nm, as well as the average ion fluences from 5 × 10 10 to 2 × 10 11 ions/cm 2 , we can control the number of ions per aperture. We analyze the photoluminescence on multiple sites with different implantation parameters and obtain ion-to-NV conversion yields of 6 − 7 %, consistent across all ion fluences. The implanted NV centers have spin dephasing times T * 2 ∼ 3 µs, comparable to naturally occurring NV centers in high purity diamond with natural abundance 13 C. With this technique, we can deterministically control the population distribution of NV centers in each aperture, allowing for the study of single or coupled NV centers and their integration into photonic structures.Advances in quantum information processing (QIP) require the use of multiple qubits that are stable and easily addressable. The NV center in diamond stands out as a candidate for this application due to its spindependent fluorescence and long coherence time at room temperature.1-4 However, the feasibility of integrating naturally occurring NV centers into a large-scale QIP architecture is limited by their random locations in the diamond lattice. The technique of nitrogen ion implantation can overcome this obstacle by offering precise control of NV center locations, while maintaining the quality of the NV centers created. 4-11In order to achieve high accuracy placement of NV centers, techniques such as implantation through a scanning force microscope tip, focused-ion beam, and apertures in implantation masks have been developed. [10][11][12] In terms of ease of fabrication and scalability, one of the most versatile methods is implantation through lithographically defined apertures. 6,13In this Letter, we study the efficacy of this method by demonstrating highly-controllable NV implantations with different ion fluences across a wide range of aperture diameters. Within each ion fluence, aperture diameters vary from 80 to 240 nm. We characterize the implanted NV centers using photoluminescence (PL) data and autocorrelation measurements g (2) (τ ). 14 Together, these data allow us to determine the statistics of NV center formation. We observe a linear relationship between the mean number of NV centers per aperture and the aperture area, from which we extract implantation yields of 6 − 7%. These yields are consistent across all ion fluences and with previously reported values.6,13,15 Finally, we measure spin dephasing times T * 2 ∼ 3 µs, a value comparable to that of naturally occurring NV centers, thus demonstrating the capability to maintain high quality NV centers and fine-tune the NV population distribution at well-defined locations. 16,17We begin by selecting an electronic grade diamond (N < 5 ppb, natural abundance 13 C, Element Six) with (100) orientation and low background PL. Typically, no NV cente...

Nuclear spins support long lived quantum coherence due to weak coupling to the environment, but are difficult to rapidly control using nuclear magnetic resonance as a result of the small nuclear magnetic moment. We demonstrate a fast ∼500  ns nuclear spin phase gate on a (14)N nuclear spin qubit intrinsic to a nitrogen-vacancy center in diamond. The phase gate is enabled by the hyperfine interaction and off-resonance driving of electron spin transitions. Repeated applications of the phase gate bang-bang decouple the nuclear spin from the environment, locking the spin state for up to ∼140  μs.