In recent years, the studies of many-body dynamics of spin ensembles in the solid state have attracted significant attention. Such studies are crucial for the understanding of fundamental problems in solid state physics such as localization and disorder in interacting systems. Furthermore, using proper Hamiltonian engineering techniques, these studies could pave the way toward the creation of non-classical spin states, leading to a variety of applications such as enhanced quantum metrology and quantum information processing.

A significant stepping stone in pursuing these directions is the ability to identify the dominant interaction sources in natural solid-state environments, as well as to controllably decouple these interactions, reaching long spin coherence times. In this work, we use a cluster-like approximation method to simulate such interactions, investigating systems of nitrogen-vacancy (NV) centers in diamond with various spin concentrations and realistic environmental conditions. Following the separate simulation of traditional dynamical decoupling pulse sequences, as well as other specialized sequences borrowed from NMR to decouple dipolar interactions, we show that the different scenarios of spin-bath dominated interactions and NV-NV dipolar dominated interactions could be distinguished. Furthermore, we show that the combined application of these sequences, as well as a strong enough continuous driving, could decouple both types of interactions, leading to very long (~50ms) coherence times (relevant for low temperature experiments). Finally, we investigate the realistic effect of finite-width pulses on these control protocols, and demonstrate the counterintuitive result of improved decoupling efficiency with increased pulse duration, which can be explained by considering the interplay of dephasing and coherent dynamics.

Our simulations consider the spin environment of NV centers in diamond, which serve as leading candidates for quantum metrology and quantum information processing, but they are applicable and relevant to any other two or three level- solid state spin systems, in which the spin state could be initialized, read-out and manipulated. The outcomes of our work could enable Hamiltonian-engineering, eventually leading to the generation of non-classical states, having a promising impact on quantum information, quantum sensing and many-body spin dynamics.

D. Farfurnik, Y. Horowicz and N. Bar-Gill, arXiv:1709.03370v3