D. Le Sage

Optical magnetic imaging of living cells

Magnetic imaging is a powerful tool for probing biological and physical systems. However, existing techniques either have poor spatial resolution compared to optical microscopy and are hence not generally applicable to imaging of sub-cellular structure (for example, magnetic resonance imaging), or entail operating conditions that preclude application to living biological samples while providing submicrometre resolution (for example, scanning superconducting quantum interference device microscopy, electron holography and magnetic resonance force microscopy). Here we demonstrate magnetic imaging of living cells (magnetotactic bacteria) under ambient laboratory conditions and with sub-cellular spatial resolution (400 nanometres), using an optically detected magnetic field imaging array consisting of a nanometre-scale layer of nitrogen–vacancy colour centres implanted at the surface of a diamond chip. With the bacteria placed on the diamond surface, we optically probe the nitrogen–vacancy quantum spin states and rapidly reconstruct images of the vector components of the magnetic field created by chains of magnetic nanoparticles (magnetosomes) produced in the bacteria. We also spatially correlate these magnetic field maps with optical images acquired in the same apparatus. Wide-field microscopy allows parallel optical and magnetic imaging of multiple cells in a population with submicrometre resolution and a field of view in excess of 100 micrometres. Scanning electron microscope images of the bacteria confirm that the correlated optical and magnetic images can be used to locate and characterize the magnetosomes in each bacterium. Our results provide a new capability for imaging bio-magnetic structures in living cells under ambient conditions with high spatial resolution, and will enable the mapping of a wide range of magnetic signals within cells and cellular networks.

Magnetic field imaging with nitrogen-vacancy ensembles

We demonstrate a method of imaging spatially varying magnetic fields using a thin layer of nitrogen-vacancy (NV) centers at the surface of a diamond chip. Fluorescence emitted by the two-dimensional NV ensemble is detected by a CCD array, from which a vector magnetic field pattern is reconstructed. As a demonstration, ac current is passed through wires placed on the diamond chip surface, and the resulting ac magnetic field patterns are imaged using an echo-based technique with sub-micron resolution over a 140µm◊140µm field of view, giving single-pixel sensitivity 100nT/ p Hz. We discuss ongoing efforts to further improve the sensitivity, as well as potential bioimaging applications such as real-time imaging of activity in functional, cultured networks of neurons.

Coherence of Nitrogen-Vacancy Electronic Spin Ensembles in Diamond

We present an experimental and theoretical study of electronic spin decoherence in ensembles of nitrogen-vacancy (NV) color centers in bulk high-purity diamond at room temperature. Under appropriate conditions, we find ensemble NV spin coherence times

Micrometer‐scale magnetic imaging of geological samples using a quantum diamond microscope

({T}_{2})

Anti-Reflection Coating for Nitrogen-Vacancy Optical Measurements in Diamond

comparable to that of single NV with

Laser-Controlled Antihydrogen Production by Two-Stage Charge Exchange

{T}_{2}g600\text{ }\ensuremath{\mu}\text{s}

First Laser-Controlled Antihydrogen Production

for a sample with natural abundance of

Antihydrogen Production within a Penning-Ioffe Trap

^{13}\text{C}

Antiproton Confinement in a Penning-Ioffe Trap for Antihydrogen

and paramagnetic impurity density

Dressed-State Resonant Coupling between Bright and Dark Spins in Diamond

\ensuremath{\sim}{10}^{15}\text{ }{\text{cm}}^{\ensuremath{-}3}