Sandia Labs FY21 LDRD Annual Report

FY21 ANNUAL REPORT

Using defects in diamonds to protect against counterfeiting and assess the behavior of electronic devices. Nitrogen-vacancy (NV) defect centers are magnetically-sensitive fluorescent defects that are used for quantum magnetic sensing in basic and applied sciences. When used to image magnetic fields from sources external to diamond, NV magnetic imagers offer room-temperature operation, micrometer-scale spatial resolution, a small sample-sensor distance (as small as a few nanometers), and parallel multi- pixel readout over a few-millimeter field of view. In this project, LDRD researchers used an NV magnetic imaging apparatus to optically image magnetic fields and yielded quantitative information about the field magnitude, direction, polarization, and relative phase with wide frequency range (DC to 100 GHz), micron resolution, and a few-millimeter field-of-view. This research demonstrated a new way to quickly read out micron-scale “magnetic fingerprints” ( to protect against counterfeiting) and to magnetically interrogate the internal currents and behaviors of integrated circuits (to probe what electronic devices are doing internally). Going forward, the goal is to advance NV magnetic imaging such that it is a useful tool for real- world national security applications, including imaging the fields from microelectronics and antennas, ion chip traps, and nanostructured devices and materials. (PI: Pauli Kehayias)

Using a surface layer of magnetically-sensitive nitrogen-vacancy centers in diamond, researchers imaged the magnetic fields from the currents in a commercial 555 timer integrated circuit (top left) when the device is in different internal states (output-on and output-off). After measuring the magnetic field maps with high spatial resolution (top row), they reconstructed the surface current densities (bottom row), allowing the team to probe the internal current paths and assess the behavior of the device.

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LABORATORY DIRECTED RESEARCH & DEVELOPMENT