An atomic electrical field sensor

This research report has now been published by Nature Physics.

There are different ways in which electrical charges control almost all physical, chemical or biological processes. For example, the exact distribution of electrons on DNA is crucial for the precise transmission of genetic information and modern electric circuits actuate electric currents up to single electrons.

However, measuring those minor electronic fields connected to the charge is still one of the most challenging tasks of measurement technology. Researchers from Stuttgart developed a novel sensor consisting of just one single atom. This nitrogen atom is an impurity captured in diamond. The diamond lattice fixes the atom, simultaneously allowing a laser to address the nuclear vacancy center. The interaction of the atom with the measured field can be determined by the light emitted by the impurity and, therefore, electrical fields can be measured which are just a fracture of the electrical field of an elementary charge in 0,1 µm distance. Since the sensor itself is only about the size of an atom, electrical fields can also be measured with the same spacial precision.

The optical readout by the sensors allows it to be placed in any geometry as desired and, furthermore, the process reaches its sensitivity and resolution at room temperature and ambient conditions. The existence of small magnetic fields has been demonstrated in the past; however, this new combination of both measurement techniques now allows measuring of the electrical as well as the magnetic field in one place without changing the sensor. This unique combination discloses new applications such as, for example, the simultaneous measuring of the magnetic moments' distribution of the chemical compounds' nuclei or the distribution of electrons in single molecules. This way, the structure of a substance and its chemical reactivity can be determined at the same time.