Diamond-nitrogen-vacancy electronic and nuclear spin-state anticrossings under weak transverse magnetic fields

We report on detailed studies of electronic and nuclear spin states in the diamond-nitrogen-vacancy (NV) center under weak transverse magnetic fields. We numerically predict and experimentally verify a previously unobserved NV hyperfine level anticrossing (LAC) occurring at bias fields of tens of gauss—two orders of magnitude lower than previously reported LACs at ∼ 500 and ∼ 1000 G axial magnetic fields. We then discuss how the NV ground-state Hamiltonian can be manipulated in this regime to tailor the NV's sensitivity to environmental factors and to map into the nuclear spin state.United States. Dept. of Defense. Assistant Secretary of Defense for Research & Engineering (Air Force Contract No. FA8721-05-C-0002)United States. Office of Naval Research (N00014-13-1-0316)United States. National Aeronautics and Space Administration ( Office of the Chief Technologist’s Space Technology Research Fellowship

In-situ depth monitoring for a deep reactive ion etcher using a white light interferometer with active vibration cancellation

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from PDF version of thesis.Includes bibliographical references (pages 119-121).Standard process development for micro and nanofabrication etching technologies relies on open-loop trial and error testing of recipes to achieve optimal etch depths and uniformities. This strategy is inefficient for research and fabrication of novel devices where one-of-a-kind experiments cannot justify lengthy process development times. This thesis describes the development of an in-situ depth measurement device for real-time feedback of etch depth and uniformity. This device will help facilitate far shorter process development times, potentially enabling the desired etch to be achieved on the first process run. The depth imager consists of a wide-field, white light interferometer with a 12" working distance, capable of imaging across a 1/2" field of view. Active feedback from a co-propagating laser interferometer is used to stabilize the system against vibrations through a feedback loop that controls the position of the reference mirror using a piezo actuator. This scheme ties the accuracy of the white light depth scan to the stability of the laser wavelength, allowing for accurate step sizes without the need for an expensive scanning stage. The well defined sampling period allows for the phase sensitive detection of the white light interference signal, reducing amplitude fluctuations from plasma emissions. This design is able to image deep trenches with optically rough surfaces, etched directly into a silicon substrate with aspect ratios of 10 or more. The device is demonstrated on a custom built deep reactive ion etcher (DRIE), achieving a depth resolution of better than 1 [mu]m in the presence of large vibrations.by Carson Teale.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienc

Magnetometry with ensembles of nitrogen vacancy centers in bulk diamond

Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (pages 55-57).This thesis summarizes experiments conducted to develop a high sensitivity vector magnetometer using nitrogen vacancy (NV) centers in a bulk diamond sample. This project began by analyzing the sensitivity of a single NV orientation using a continuous wave electron spin resonance approach. A protocol for determining the diamond's orientation was developed to map vector magnetic field readings in the diamond reference frame to the lab frame. Preliminary vector field measurements and differential vector measurements were performed. Although these showed promising results, significant instrument and ambient magnetic noise limited the achievable sensitivity. A new frequency locking measurement technique was developed to allow for simultaneous measurements between two separate sensors for future differential experiments. This technique provides a host of other benefits including much improved dynamic range and steady-state immunity to fluctuations in linewidth and contrast.by Carson Teale.S.M