Quantum Optics Seminar by Kasper Jensen – Niels Bohr Institute - University of Copenhagen

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Quantum Optics Seminar by Kasper Jensen

Nitrogen-vacancy (NV) centers in diamond are promising candidates for quantum sensing, nano-scale imaging and quantum information processing.

Ensembles of NV centers are useful since for instance the sensitivity to detecting magnetic fields improve with increasing number of NV centers.

Ultimatively, the magnetic field sensitivity is limited by longitudinal relaxation (T1) processes. In this talk, I will present measurements of T1 as a function of temperature (5 to 475 K) and magnetic field for different diamond samples with different Nitrogen and NV concentrations. At low temperatures, T1 is limited by cross-relaxation with other spins. 

Magnetic fields can be detected using an  "optically detected magnetic resonance" (ODMR) technique. We have studied ODMR signals for a wide range of light powers and micro-wave powers and have found that the linewidth of the OMDR signal can decrease with increasing light power. This is called a light narrowing effect, which is important for optimizing magnetic field sensitivity. 

Finally, I will discuss preliminary measurements towards electro-magnetically induced transparancy (EIT) and quantum memory in ensembles of NV centers.