07/04/2014
High-Precision Nanosensors: 10 Year old Theoretical Proposal Implemented
Scientists at the Swiss Nanoscience Institute at the University of Basel were able to show that specifically modified diamonds could work as high precision nanosensors. The researchers used single crystal diamond cantilevers with embedded defects in their crystal lattice structure. In these so called nitrogen-vacancy centers the spin of single electrons can be observed and manipulated. The researchers thereby implemented an experiment that was suggested in theory 10 years ago.
Diamonds are not only are a girl's best friend, they are also of great interest to scientists all over the world. Their carbon lattice can be modified by replacing a carbon atom with a nitrogen atom and additionally generating a vacancy right next to it. Within a so called nitrogen-vacancy center a single electron is trapped. Its spin can be measured by optically exciting the electron to emit light.
The team of scientists around Georg-H. Endress Professor Patrick Maletinsky from the Swiss Nanoscience Institute at the University of Basel used these modified diamonds to nano-fabricate diamond cantilevers. For the first time, they could show that the spin of a captured electron changes upon bending or putting in motion of the cantilever. In 2004, ETH-Professor Atac Imamoglu and his former student Ignacio Wilson-Rae theoretically proposed such an experiment, but it could not be experimentally realized up until now.
Connections between spin and cantilever
Crucial to this coupling are tensions that develop when the diamond lattice is strained. When the cantilever is used to scan a surface or is set in motion via an electrical impulse, this movement can be measured via the coupling to the electron spins. With the help of these high precision sensors, tiny signals may potentially be detected and used to produce highly detailed images of nanostructures or to detect small amounts of single chemical compounds.
With these experiments, the physicists move at the border between classical and quantum mechanics. However, the results not only help defining this border, they can also be used towards applications. In the future, these single crystal diamonds may be used as sensors in materials science, nanotechnology or even biology. They work at room temperature and are, unlike many other sensors, biologically inert, meaning that they could also be used for biological tissue.
However, the researchers at the University of Basel are still far from the application. "At the moment we are incredibly excited that we were the first to experimentally show this coupling", Patrick Maletinsky comments on his findings. "We could also demonstrate that our system is very stable. This will help us in future experiments aimed at exploring the border between quantum mechanics and classical physics."
Source: University of Basel