Final Report Summary - SQUTEC (Solid State Quantum Technology and Metrology Using Spins)
In the course of the project a variety of sensing modalities were investigated. Most notably we demonstrated detection of the electric field of a single electron spin under ambient conditions. We also succeeded in precision temperature measurements using single defects. To this end, a novel spin decoupling method was used to eliminate noise effects from e.g. magnetic fields on the single spin dynamics, and achieve a mK measurement accuracy over a 1s averaging time and with nanoscale spatial resolution. In a further set of experiments we were exploring methods to enhance the magnetic field sensitivity in our experiments. For a single defect the magnetic field sensitivity is limited by the dephasing time of the defect (ms at room temperature) and the signal-to-noise ratio for the spin readout. To make efficient use of the measurement time we developed a phase estimation technique to enhance scaling of measurement precision with time beyond the standard quantum limit. We were using improved sample fabrication and implantation technology to enable sensing of nuclear spin magnetism. By employing nitrogen vacancy (NV) defect centers implanted a few nanometers below the diamond surface we succeeded in the defection of a the nuclear magnetic resonance signal of a few hundred proton spins. We have elaborated on this achievement in various directions. On the one hand, we were able to detect the electron spin resonance signature of a single protein under ambient conditions. On the other hand, we imaged nuclear spins in a polymer sample using a scanning probe magnetometer. In this set of experiments we demonstrated magnetic resonance imaging (MRI) experiments with chemical contrast and a spatial resolution of around 20nm. In a separate set of experiments we applied the technique to demonstrate MRI on biological cells.