A quiet revolution is taking place in the nanoworld. Quantum engineers are shaping a new generation of devices based on phenomena known as quantum superposition (a particle can be in two different states at the same time) or quantum entanglement (two remote particles may communicate instantaneously over arbitrary distances).
QNAMI applies this new physics to sensing. By precisely controlling and measuring the state of a single electron, we are able to measure electric and magnetic fields with excellent sensitivity. Furthermore, our nano-sensors produce images with unique resolution on the nano-meter scale. We call this quantum sensing, a technique which is being developed in the quantum sensing group in Basel.
COLOR CENTERS IN DIAMOND
Diamond is an outstanding material and this is true for quantum applications too!
We use synthetic diamond fabricated in growth chambers at very high temperature and pressure. From a technique called Chemical Vapor Deposition (CVD), one is able to obtain synthetic diamonds with a purity exceeding the one of natural diamonds by far. We buy such diamond and upgrade them for quantum applications by introducing color centers in it.
Color centers are tiny defects that can be artificially implanted into the diamond crystal lattice. They trap an electron, which we use as a quantum sensor. The color centers in diamond present a number of advantages. As their name suggests, they emit light in the visible range. We use it for signal read-out. They also display very long coherence times, a key parameter for quantum applications.
Finally, diamond material is robust, inert and bio-compatible allowing for non-perturbing measurement in the most challenging environments.
SCANNING PROBE MICROSCOPY
In order to deliver images with nanometer resolution, our diamonds are processed into sharp tips with sub-micron dimensions. Each tip contains one quantum sensor that measures external fields. By scanning the tip, one records images of the magnetic or electric fields produced by any sample sitting below.
The spatial resolution is given by the flight distance between the quantum sensor (the color center within the diamond matrix) and the surface. Even in ambient conditions, this value gets as small as 30 nm.
Data read-out is performed optically. Our diamond probes are designed to optimize extraction efficiency and ensure maximum sensitivity. The diamond tip (green) is positioned with the color center in the focus of the objective. Images are obtained from a contrast in the detected fluorescence as the sample (purple) is scanned.