NV-center in diamond as a single molecular sensor
The negatively charged nitrogen-vacancy (NV) defect in diamond has properties that make it an ideal sensor for practical electronic and nuclear spin detection applications. The NV-centre has a paramagnetic ground state with long coherence time that can be initialized by optical radiation (spin polarization) and the electronic spin state can be read out optically, all at room temperature. These traits make the NV-centre a promising candidate for quantum computing, and a source of single photons. In this work we are interested in applications with a single NV-centre as a detector in no less than three applications: single molecule magnetic resonance spectroscopy (NMR); readout of nuclear spin based qubits; and single molecule fluorescence resonance energy transfer (FRET). These three applications are at the conceptual stage and all require surface-near NV-centres, and there is a knowledge gap in how the surface and the local environment affects the NV-centre properties. In the light of these novel possible applications using the NV-centre we will address the following objectives:
• Investigate how to enable these new single molecule detection applications utilizing the NV-centre.
o We have compared the NV-centre properties using different density functional theory functional types (local density approximation (LDA), generalized gradient approximation (GGA), and hybrid-functional (HSE06)) to find the pros and cons of the different choices (year 1, in manuscript)
o We have studied the NV-centre’s energy levels when perturbed by a nearby substitutional defect, with regard to distance and angle to the N-V direction in a bulk model (year 1, in manuscript)
o We have also begun the study of another colour-centre in diamond, the SiV-centre, that has gotten a lot of attention in recent papers in the field (year 2, present application)
• Determine the effect the surface has on the properties of shallow NV-centres, including the influence from other local environment effects, such as geometry and defects.
o We have established a favourable surface termination (fluorine) for these types of application, and have built large scale slab-models to investigate how the colour-centre properties are influenced by the depth from the surface (year one, in manuscript). This work is proving to be extremely important because we have designed models that circumvent the problems with the computation of charged defects (the NV-centre is negatively charged in its most common form) in slab models, which are caused by the counter-charge. Thus, our work will be the first simulations that are free from such concerns (year 2, present application)
• Explore the interactions between the NV-centre and diamond surface bound molecules in realistic measurement set-ups.
o A postdoc has been hired (Dr. Ravinder Pawar, starting May 2014) who will work on molecules bound to the fluorine terminated diamond surface (year 2, present application)