Nanoscale microwave imaging with a single electron spin in diamond

Abstract

We report on imaging of microwave (MW) magnetic fields using a magnetometer based on the electron spin of a nitrogen vacancy (NV) center in diamond. We quantitatively image the magnetic field generated by high frequency (GHz) MW current with nanoscale resolution using a scanning probe technique. Together with a shot noise limited MW magnetic field sensitivity of 680 nT Hz −1/2 our room temperature experiments establish the NV center as a versatile and high performance tool for MW imaging, which furthermore offers polarization selectivity and broadband capabilities. As a first application of this scanning MW detector, we image the MW stray field around a stripline structure and thereby locally determine the MW current density with a MW current sensitivity of a few nA Hz −1/2 .

Determination of intrinsic effective fields and microwave polarizations by high-resolution spectroscopy of single nitrogen-vacancy center spins

“…Examples for these include nanoscale magnetic imaging of magnetically sensitive samples [32], or NV-based low-field techniques like zero and ultra-low field NMR [33]. The novel MW polarization analysis we demonstrated could find applications in NV-based MW imaging [34,35], which until now was only demonstrated for sensing of circularly polarized MWs [36]. Our results extend these capabilities and the existing toolset of NV-based quantum sensing modalities and would in principle allow for determining the full polarization state of MW fields with nanoscale resolutions, which has relevance in MW electronics [37] or spintronics devices [38].…”

Widefield microwave imaging in alkali vapor cells with sub-100μm resolution

“…Our microwave detection technique is not limited to 87 Rb, and can be applied to any system comprised of two states coupled by a microwave transition with optical read-out of the states, including the other alkali atoms, and solid state 'atom-like' systems, such as NV centers [52]. NV center-based imaging systems provide nanoscale resolution and typically work in scanning mode.…”

Nanoscale Sensing Using Point Defects in Single-Crystal Diamond: Recent Progress on Nitrogen Vacancy Center-Based Sensors

“…However, NV centers are also sensitive to magnetic fields oscillating at GHz frequencies: single-crystal NV scanning probes imaged magnetic fields generated by MW currents with nanoscale resolution and sensitivity of a few nA·Hz 1/2 [30]. The basic idea is to tune an NV spin resonance to the investigated MW frequency using a static magnetic field.…”

“…As these levels have a lifetime that is more than one order of magnitude longer than for the triplet levels [29], the NV's photo-luminescence is reduced in the ±1 states enabling the optical read-out of the NV spin state (optically-detected magnetic resonance (ODMR)). For sensing applications, transitions between the 0 state and +1 or −1 state are typically driven using circularly-polarized microwaves (MW) [23,30]. Using green laser light (532 nm), the NV center is initialized to its m s = 0 state via optical pumping within roughly 1 µs [31].…”