Zhang, Zhiran | Engineering Papers

DOE OSTI2023

Reporter-Spin-Assisted T 1 Relaxometry

A single-spin quantum sensor can quantitatively detect and image fluctuating electromagnetic fields via their effect on the sensor spin’s relaxation time, thus revealing important information about the target solid-state or molecular structures. However, the sensitivity and spatial resolution of spin relaxometry are often limited by the distance between the sensor and target. Here, we propose an alternative approach that leverages an auxiliary reporter spin in conjunction with a single-spin sensor, a diamond nitrogen-vacancy (N-V) center. We show that this approach can realize a 100-fold measurement sensitivity improvement for realistic working conditions and we experimentally verify the proposed method using a single shallow N-V center. Our work opens up a broad path of inquiry into a range of possible spin systems that can serve as relaxation sensors without the need for optical initialization and readout capabilities.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2023

Two-dimensional spin systems in PECVD-grown diamond with tunable density and long coherence for enhanced quantum sensing and simulation

Systems of spins engineered with tunable density and reduced dimensionality enable a number of advancements in quantum sensing and simulation. Defects in diamond, such as nitrogen-vacancy (NV) centers and substitutional nitrogen (P1 centers), are particularly promising solid-state platforms to explore. However, the ability to controllably create coherent, two-dimensional spin systems and characterize their properties, such as density, depth confinement, and coherence, is an outstanding materials challenge. We present a refined approach to engineer dense (≳1 ppm ∙ nm), 2D nitrogen, and NV layers in diamond using delta-doping during plasma-enhanced chemical vapor deposition epitaxial growth. We employ both traditional materials techniques, e.g., secondary ion mass spectrometry, alongside NV spin decoherence-based measurements to characterize the density and dimensionality of the P1 and NV layers. We find P1 densities of 5–10 ppm ∙ nm, NV densities between 1 and 3.5 ppm ∙ nm tuned via electron irradiation dosage, and depth confinement of the spin layer down to 1.6 nm. We also observe high (up to 0.74) ratios of NV to P1 centers and reproducibly long NV coherence times, dominated by dipolar interactions with the engineered P1 and NV spin baths.

36 MATERIALS SCIENCE↗