Optical Quantum Metrology and Sensing

Levitated Optomechanics

This field of work deals with optically trapped nanoparticles. The motion of the particles can be strongly reduced by paramertic cooling, in extreme cases down to the quantum mechanical ground state. At the same time, the position is read out interferometrically with high precision, resulting in a promising measurement system. 

At BIAS, we pursue fundamental physics questions as well as practical measurement applications in this field. The use in the drop tower in Bremen, or later in space, offers unique possibilities to explore the limits of quantum physics, while at the same time we investigate the usage for inertial navigation or precise measurements of local gravity.

NV Center Magnetometry

Nitrogen vacancies (NV centers) are defects in the crystal structure of diamond. They consist of a nitrogen atom and an adjacent unoccupied vacancy. The resulting unbound electrons can be optically excited and read out. At the same time, their behavior is magnetic field dependent.

The system is of particular interest to us at BIAS because of its robustness and user-friendliness. NV-center magnetometry allows precise measurements of magnetic fields in a large measurement range and relatively strong background fields. As a first application, we aim to use it on satellites. This extreme environment should underpin the advantages of the system also for industrial applications.

Undetected Photons

In nonlinear crystals, light particles can decay and form two new particles. These must satisfy energy conservation, but can have completely different wavelengths. For example, correlated photons are formed in the visible and infrared spectra. 

The idea now is to make a measurement in the infrared, where many gases absorb but the detectors have a high noise level, and to detect in the visible, where very good cameras are available. Quantum mechanics allows this, since the photons have common properties and are not independent of each other.