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Colloquium by Jean-François Roch @CQT & @NTU

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Colloquium by Jean-François Roch @CQT & @NTU

Magnetic imaging with point defects in diamond

Date: 10 November 2016, Thursday
Time: 4pm-5pm
Venue: CQT Level 3 Seminar Room, S15-03-15

Abstract: The ability to quantitatively map magnetic field distributions is of crucial importance for fundamental studies ranging from materials science to biology, and for the development of new devices e.g. in spintronics. Recently it has been demonstrated that scanning magnetometry based on a single spin associated to an impurities hosted in a solid is an efficient technique which combines high sensitivity and nanoscale resolution. The sensing signal relies on the optical detection of the electron spin resonance associated with a single nitrogen-vacancy (NV) center in diamond attached to a AFM tip. The magnitude of the stray magnetic field above a magnetic sample can then be determined from the Zeeman shifts of the energy levels associated to this artificial atom in the solid state.

Extending this technique to a cryogenic environment will open the way to investigate many magnetic phenomena occuring in complex condensed matter systems, such as superconductivity or the magnetic properties of strongly correlated systems. I will present our recent realizations of a scanning magnetometer based on NV centers in a nanodiamond grafted at the apex of a AFM tip, and how they have been applied to the imaging of magnetic nanostructures. I will also describe how NV centers can be efficiently engineered by combining plasma-assisted diamond growth and nanoscale ion implantation.

Video (coming soon):

Tailoring the properties of NV color centers in diamond

Date: 11 November 2016, Friday
Time: 4pm-5pm
Venue: Hilbert Space (PAP-02-02), NTU

Abstract: The Nitrogen-Vacancy (NV) color center is a point defect in diamond which behaves as an artificial atom hosted in a solid-state matrix. Due to its electron spin properties which can be read-out and manipulated as an elementary quantum system even at room temperature, the NV center has found a wide panel of applications as a qubit for quantum information and as a magnetic field sensor. However these applications require to control the properties of the NV centers and their localization. I will describe methods aimed to tailor the properties of NV centers by combining techniques for the implantation of nitrogen atoms then converted into NV centers and for the plasma-assisted (CVD) synthesis of diamond.

Biography Jean-Francois Roch was a student of the "école normale supérieure" of Cachan before doing his PhD at the institute of Optics under the direction of Philippe Grancier in 1992. The same year he joined CNRS as a "chargé de recherche". In 1998, Jean-François Roch becomes full professor. He is now the director of the "laboratoire Aimé-Cotton" at University Paris South. Jean-François Roch is an international recognized expert in quantum optics, non-destructive measurement, superconducting circuit and NV-centers.