Non-flipping¹³C spins near an NV center in diamond: hyperfine and spatial characteristics by density functional theory simulation of the C₅₁₀[NV]H₂₅₂cluster

Abstract

Single NV centers in diamond coupled by hyperfine interaction (hfi) to neighboring 13 C nuclear spins are now widely used in emerging quantum technologies as elements of quantum memory adjusted to a nitrogen-vacancy (NV) center electron spin qubit. For nuclear spins with low flip-flop rate, single shot readout was demonstrated under ambient conditions. Here we report on a systematic search for such stable NV− 13 C systems using density functional theory to simulate the hfi and spatial characteristics of all possible NV− 13 C complexes in the H-terminated cluster C 510 [NV] -H 252 hosting the NV center. Along with the expected stable 'NV-axial− 13 C' systems wherein the 13 C nuclear spin is located on the NV axis, we found for the first time new families of positions for the 13 C nuclear spin exhibiting negligible hfi-induced flipping rates due to near-symmetric local spin density distribution. Spatially, these positions are located in the diamond bilayer passing through the vacancy of the NV center and being perpendicular to the NV axis. Analysis of available publications showed that, apparently, some of the predicted non-axial near-stable NV− 13 C systems have already been observed experimentally. A special experiment performed on one of these systems confirmed the prediction made.

Three-dimensional localization spectroscopy of individual nuclear spins with sub-Angstrom resolution

“…The Fermi contact interaction adds an isotropic term to the hyperfine coupling tensor, A + a iso 1 , which modifies the diagonal elements A xx , A yy , and A zz . DFT simulations 25 , 26 indicate that a iso can exceed 100 kHz even for nuclear spins beyond 7 Å. It is therefore important to experimentally constrain the size of a iso .…”

Hyperfine Interactions in the NV-13C Quantum Registers in Diamond Grown from the Azaadamantane Seed

“…It will be done by rotating the cluster C 510 [NV]-H 252 with the ChemCraft software package to obtain the desired relative configuration of the NV1–NV8 centers and various isotopic seeds. This makes it possible to identify the numbers j of the carbon atoms C(j) belonging to the seed in accordance with their numbering in the cluster of the article [ 33 ] and then using the Supplement to the article, one can find the hfi characteristics for this specific NV- 13 C(j) system obtained from respective seed as a result of diamond growth and creation a vacancy in one of the lattice site near the nitrogen atom. The results of such analysis are presented below in the Table 1 both for 2- and 1-azaadamantane seeds.…”

Algorithmic decomposition for efficient multiple nuclear spin detection in diamond

“…Owing to the long coherence times of these nuclear spins 18 , detecting and manipulating naturally trapped nuclear spins in diamond through NV centers is emerging as a promising pathway to enable controlled quantum systems such as spin qubit registers [19][20][21][22][23][24] , quantum networks 25,26 , quantum simulation platforms 18,27 , and quantum memories [28][29][30] . Because naturally occurring 13 C nuclear spins are randomly located around an NV center electron spin 31,32 , the efficient and automatic characterization of hyperfine interactions of individual nuclear spins is a prerequisite step towards building scalable quantum systems based on this platform.…”

“…Automatic methods that efficiently and objectively detect and characterize the underlying nuclear spins are required for further scalability of this platform. The detection of nuclear spins in diamond relies on the hyperfine coupling to NV center electron spin, and combined effects from each spin are reflected in the spectrum signal 31,32 . To identify each spin individually, the signal should be decomposed into multiple spectra, each resulting from a single nuclear spin.…”