Date: April 19, 2011, No. 31

Further successes with quantum diamonds

Publication in Nature Physics and DFG research group

Researchers from the 3. Institute of Physics as well as Stuttgart Research Centers für Photonische Technologien (SCoPe) of the University of Stuttgart have succeeded in measuring electric fields with one single atomic imperfection in diamond. With this the structure of a substance and its chemical reactivity can be simultaneously determined in future. The renowned journal Nature Physics*) is now reporting on these measurements. The successes of the Stuttgart scientists in the field of quantum diamonds was also honoured by the Deutsche Forschungsgemeinschaft DFG, which approved the facility of DFG Research Group „Diamond Materials and Quantum Application“ at the University of Stuttgart in its meeting in April.

Quantum physics is increasing changing to the research field of quantum technology thanks to an ever greater understanding and easily controllable experiments. In the meantime, physicists are now able to tailor make material and influence quantum dynamics, which opens up a diverse range of application possibilities, for example in information processing or sensor technology. With diamond the research group „Diamond Materials and Quantum Application“ (spokesperson: Prof. Jörg Wachtrup, 3. Institute of Physics at the University of Stuttgart) is dedicating itself to a very promising quantum material and is using the technological basics to set up better controlled and increasingly complex diamond structures. To do this the research group is bringing together experts on material growth, structuring and defect creation but also quantum optics and spintronics. Above all they are focusing on the use of „ quantum diamonds“ in the fields of quantum photonics and spintronics. The findings of the research group could, however, also be used in medicine in future.

High precision measurement of electric fields
In the research work now published in Nature Physics the Stuttgart researchers are dedicating themselves to the great physical challenge of measuring electric fields. Such fields play a decisive role in different places in nature and technology. Nerve impulses are transferred, for example, through the change of electric fields and also modern data storage such as, for example on USB sticks is based on the storage of electrical charge. The high precision measurement of the small electric fields associated with the charges is, however, one of the most demanding areas in metrology. The Stuttgart researchers have developed a unique sensor for this comprising only one single atom. This nitrogen atom is contained in diamond as an impurity. The diamond lattice fixates the atom and enables it at the same time to address the atomic imperfection with the help of a laser. The interaction of the atom with the field to be measured can be determined by means of the light emitted again by the imperfection. In this way it is possible to measure electric fields corresponding to a fraction of an elementary charge at a distance of 0.1 micrometres. Since the sensor itself has about the same dimensions of an atom, electric fields can likewise be measured with this spatial precision. The optical selection of the sensor makes it possible to attach the sensor in any chosen geometry. In addition, the process reaches its sensitivity and resolution at room temperature and in ambient conditions.

In the past scientists were already able to demonstrate evidence of small magnetic fields with the same process. It has now been possible for the first time to determine the electric as well as magnetic field in the same place without having to change the sensor. This unique combination opens up completely new possibilities, for example the simultaneous measuring of the distribution of magnetic moments of the core of chemical bonds as well as the charge distribution of electrons in single molecules.

*) Florian Dolde, Helmut Fedder, Marcus W. Doherty, Tobias Nöbauer, Florian Rempp, Gopalakrishnan. Balasubramanian, ThomasWolf, Friedemann Reinhard, Lloyd C.L. Hollenberg, Fedor Jelezko and Jörg Wrachtrup: Sensing electric fields using single diamond spins – Nature physics 10.1038/NPHYS1969

Further information from Prof. Jörg Wrachtrup, University of Stuttgart, 3. Institute of Physics, tel. 0711/685-65278, e-mail: