0000000001284579
AUTHOR
Takeshi Ohshima
Photoluminescence at the ground-state level anticrossing of the nitrogen-vacancy center in diamond: A comprehensive study
Physical review / B 103(3), 035307 (2021). doi:10.1103/PhysRevB.103.035307
NATO Advanced Research Workshop on Explosives Detection
As of 2017, there are an estimated 100 million abandoned land mines littered across 61 countries. Following the wars in Afghanistan, Libya, Syria, Yemen, and Ukraine, there has been a rise in casualties due to the triggering of previously-abandoned explosive devices. The above institutions combined specialties to develop a remotely-operable, multisensor, robotic device for the detection of land mines, UXO (1), and IEDs (2). The robotic detection device uses novel subsurface radar with imaging and target classification to differentiate between threatening landmines and innocuous clutter. The expected outcome of this research is the creation of a multi-sensor system on a semi-autonomous vehic…
Zero-field magnetometry based on nitrogen-vacancy ensembles in diamond
Ensembles of nitrogen-vacancy (NV) centers in diamonds are widely utilized for magnetometry, magnetic-field imaging and magnetic-resonance detection. They have not been used for magnetometry at zero ambient field because Zeeman sublevels lose first-order sensitivity to magnetic fields as they are mixed due to crystal strain or electric fields. In this work, we realize a zero-field (ZF) magnetometer using polarization-selective microwave excitation in a 12C-enriched HPHT crystal sample. We employ circularly polarized microwaves to address specific transitions in the optically detected magnetic resonance and perform magnetometry with a noise floor of 250 pT/Hz^(1/2). This technique opens the …
Scientific and Technical Contributions from Research Projects
The main goal of this project is to demonstrate the advantages of sensor integration on a remotely controlled robotic platform for increasing operator safety and improving the classification of explosive targets. This is accomplished by combining the imaging provided by radars and an optoelectronic sensor, a time-of-flight (ToF) depth camera. An additional aim is to demonstrate the operability and practicality of the system in a field with landmine simulants having plastic cases.
Microwave-free vector magnetometry with nitrogen-vacancy centers along a single axis in diamond
Sensing vector magnetic fields is critical to many applications in fundamental physics, bioimaging, and material science. Magnetic-field sensors exploiting nitrogen-vacancy (NV) centers are particularly compelling as they offer high sensitivity and spatial resolution even at nanoscale. Achieving vector magnetometry has, however, often required applying microwaves sequentially or simultaneously, limiting the sensors' applications under cryogenic temperature. Here we propose and demonstrate a microwave-free vector magnetometer that simultaneously measures all Cartesian components of a magnetic field using NV ensembles in diamond. In particular, the present magnetometer leverages the level ant…
Photoluminescence at the ground state level anticrossing of the nitrogen-vacancy center in diamond
The nitrogen-vacancy center (NV center) in diamond at magnetic fields corresponding to the ground state level anticrossing (GSLAC) region gives rise to rich photoluminescence (PL) signals due to the vanishing energy gap between the electron spin states, which enables to have an effect on the NV center's luminescence for a broad variety of environmental couplings. In this article we report on the GSLAC photoluminescence signature of NV ensembles in different spin environments at various external fields. We investigate the effects of transverse electric and magnetic fields, P1 centers, NV centers, and the $^{13}$C nuclear spins, each of which gives rise to a unique PL signature at the GSLAC. …