Wide-field strain imaging with preferentially aligned nitrogen-vacancy centers in polycrystalline diamond

We report on wide-field optically detected magnetic resonance imaging of nitrogen-vacancy centers (NVs) in type IIa polycrystalline diamond. These studies reveal a heterogeneous crystalline environment that produces a varied density of NV centers, including preferential orientation within some individual crystal grains, but preserves long spin coherence times. Using the native NVs as nanoscale sensors, we introduce a three-dimensional strain imaging technique with high sensitivity (<10⁻⁵Hz⁻½) and diffraction-limited resolution across a wide field of view.United States. Office of Naval Research (N00014-13-1-0316)United States. Air Force Office of Scientific Research. Multidisciplinary University Research Initiative I(FA9550-14-1-0052)United States. Air Force Office of Scientific Research (Presidential Early Career Award

Wide-Field Imaging Using Nitrogen Vacancies

Nitrogen vacancies in bulk diamonds and nanodiamonds can be used to sense temperature, pressure, electromagnetic fields, and pH. Unfortunately, conventional sensing techniques use gated detection and confocal imaging, limiting the measurement sensitivity and precluding wide-field imaging. Conversely, the present sensing techniques do not require gated detection or confocal imaging and can therefore be used to image temperature, pressure, electromagnetic fields, and pH over wide fields of view. In some cases, wide-field imaging supports spatial localization of the NVs to precisions at or below the diffraction limit. Moreover, the measurement range can extend over extremely wide dynamic range at very high sensitivity

Nanoscale engineering of spin-based quantum devices in diamond

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.Cataloged from PDF version of thesis. Page 72 in the original document contain text that runs off the edge of the page.Includes bibliographical references (pages 129-155).The development of quantum technologies from the bottom-up requires engineering and control at the level of single quanta. In this thesis, we explore the engineering of a particular quantum system: optically active defects in diamond, known as color centers. Color centers have a variety of advantageous characteristics, including long-lived quantum phase coherence in their electron spin degrees of freedom, available highfidelity control and readout at the single-spin level, and strong interactions with other quantum systems such as photons. In addition, color centers can be controllably created and their local environment shaped through semiconductor fabrication processes that form a toolkit for engineering quantum devices on the nanoscale. We apply this toolkit to several challenges: the development of sensitive spin-based magnetometers with high spatial resolution, the production of tightly-confined spin clusters for use as small quantum computers, quantum memories or magnetic resonance sensors, and the integration of spin qubits with optical nanostructures as spin-photon interfaces. In parallel, we develop metrology techniques to characterize our quantum devices, and apply these techniques to the problem of wide-field strain imaging in polycrystalline diamond. The devices shown here are building blocks for the development of future scaled quantum technologies, while the engineering and metrology toolkit we developed has direct application to the quickly growing field of semiconductor color center science.by Matthew Edwin Trusheim.Ph. D

Low-control and robust quantum refrigerator and applications with electronic spins in diamond

We propose a general protocol for low-control refrigeration and thermometry of thermal qubits, which can be implemented using electronic spins in diamond. The refrigeration is implemented by a probe, consisting of a network of interacting spins. The protocol involves two operations: (i) free evolution of the probe; and (ii) a swap gate between one spin in the probe and the thermal qubit we wish to cool. We show that if the initial state of the probe falls within a suitable range, and the free evolution of the probe is both unital and conserves the excitation in the $z$-direction, then the cooling protocol will always succeed, with an efficiency that depends on the rate of spin dephasing and the swap gate fidelity. Furthermore, measuring the probe after it has cooled many qubits provides an estimate of their temperature. We provide a specific example where the probe is a Heisenberg spin chain, and suggest a physical implementation using electronic spins in diamond. Here the probe is constituted of nitrogen vacancy (NV) centers, while the thermal qubits are dark spins. By using a novel pulse sequence, a chain of NV centers can be made to evolve according to a Heisenberg Hamiltonian. This proposal allows for a range of applications, such as NV-based nuclear magnetic resonance of photosensitive molecules kept in a dark spot on a sample, and it opens up possibilities for the study of quantum thermodynamics, environment-assisted sensing, and many-body physics

Investigation of the Stark Effect on a Centrosymmetric Quantum Emitter in Diamond

Quantum emitters in diamond are leading optically-accessible solid-state qubits. Among these, Group IV-vacancy defect centers have attracted great interest as coherent and stable optical interfaces to long-lived spin states. Theory indicates that their inversion symmetry provides first-order insensitivity to stray electric fields, a common limitation for optical coherence in any host material. Here we experimentally quantify this electric field dependence via an external electric field applied to individual tin-vacancy (SnV) centers in diamond. These measurements reveal that the permanent electric dipole moment and polarizability are at least four orders of magnitude smaller than for the diamond nitrogen vacancy (NV) centers, representing the first direct measurement of the inversion symmetry protection of a Group IV defect in diamond. Moreover, we show that by modulating the electric-field-induced dipole we can use the SnV as a nanoscale probe of local electric field noise, and we employ this technique to highlight the effect of spectral diffusion on the SnV.Comment: 6 pages, 4 figure