57 research outputs found
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 ppmnm), 2D nitrogen and NV layers in
diamond using delta-doping during plasma-enhanced chemical vapor deposition
(PECVD) epitaxial growth. We employ both traditional materials techniques, e.g.
secondary ion mass spectrometry (SIMS), 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 ppmnm, NV densities between 1 and
3.5 ppmnm tuned via electron irradiation dosage, and depth confinement
of the spin layer down to 1.6 nm. We also observe high (up to 42)
conversion of P1 to NV centers and reproducibly long NV coherence times,
dominated by dipolar interactions with the engineered P1 and NV spin baths
Probing many-body noise in a strongly interacting two-dimensional dipolar spin system
The most direct approach for characterizing the quantum dynamics of a
strongly-interacting system is to measure the time-evolution of its full
many-body state. Despite the conceptual simplicity of this approach, it quickly
becomes intractable as the system size grows. An alternate framework is to
think of the many-body dynamics as generating noise, which can be measured by
the decoherence of a probe qubit. Our work centers on the following question:
What can the decoherence dynamics of such a probe tell us about the many-body
system? In particular, we utilize optically addressable probe spins to
experimentally characterize both static and dynamical properties of
strongly-interacting magnetic dipoles. Our experimental platform consists of
two types of spin defects in diamond: nitrogen-vacancy (NV) color centers
(probe spins) and substitutional nitrogen impurities (many-body system). We
demonstrate that signatures of the many-body system's dimensionality, dynamics,
and disorder are naturally encoded in the functional form of the NV's
decoherence profile. Leveraging these insights, we directly characterize the
two-dimensional nature of a nitrogen delta-doped diamond sample. In addition,
we explore two distinct facets of the many-body dynamics: First, we address a
persistent debate about the microscopic nature of spin dynamics in
strongly-interacting dipolar systems. Second, we demonstrate direct control
over the spectral properties of the many-body system, including its correlation
time. Our work opens the door to new directions in both quantum sensing and
simulation.Comment: 10 + 8 + 5 pages; 3 + 5 figure
Diamond Surface Functionalization via Visible Light-Driven C-H Activation for Nanoscale Quantum Sensing
Nitrogen-vacancy centers in diamond are a promising platform for nanoscale
nuclear magnetic resonance sensing. Despite significant progress towards using
NV centers to detect and localize nuclear spins down to the single spin level,
NV-based spectroscopy of individual, intact, arbitrary target molecules remains
elusive. NV molecular sensing requires that target molecules are immobilized
within a few nanometers of NV centers with long spin coherence time. The inert
nature of diamond typically requires harsh functionalization techniques such as
thermal annealing or plasma processing, limiting the scope of functional groups
that can be attached to the surface. Solution-phase chemical methods can be
more readily generalized to install diverse functional groups, but they have
not been widely explored for single-crystal diamond surfaces. Moreover,
realizing shallow NV centers with long spin coherence times requires highly
ordered single-crystal surfaces, and solution-phase functionalization has not
yet been shown to be compatible with such demanding conditions. In this work,
we report a versatile strategy to directly functionalize C-H bonds on
single-crystal diamond surfaces under ambient conditions using visible light.
This functionalization method is compatible with charge stable NV centers
within 10 nm of the surface with spin coherence times comparable to the state
of the art. As a proof of principle, we use shallow ensembles of NV centers to
detect nuclear spins from functional groups attached to the surface. Our
approach to surface functionalization based on visible light-driven C-H bond
activation opens the door to deploying NV centers as a broad tool for chemical
sensing and single-molecule spectroscopy
Colour centre generation in diamond for quantum technologies
Effective methods to generate colour centres in diamond and other wide band-gap materials are essential to the realisation of solid state quantum technologies based on such systems. Such methods have been the subject of intensive research effort in recent years. In this review, we bring together the various techniques used in the generation and positioning of colour centres in diamond: ion implantation, delta-doping, electron irradiation, laser writing and thermal annealing. We assess the roles and merits of each of these techniques in the formation of colour centres for different quantum technologies and consider future combinations of the techniques to meet the requirements of the most demanding applications
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