Quantum sensors have been defined as measurement devices whose sensing capabilities are “enabled by our ability to manipulate and read out their quantum states”.

The quantum states of neutrons are commonly exploited for physics measurements, but “true” quantum sensing has proved elusive: most measurement devices rely on independent means for upstream state selection, or even infer quantum structures from measurements that do not intrinsically exploit them.

This project opens the door to quantum sensing with neutrons, through development of innovative neutron detectors that directly exploit the quantum mechanical coupling of free neutrons to lossy resonators. The detection probability strongly depends on spatial structure in the neutron’s wavefunction at the detector entrance, and arises entirely from interactions in absorbing layers that can only be reached by tunneling. This implies wide-ranging possibilities, e.g., quantum selection of extremely narrow momentum ranges, which are enabled according to the precise sequence of reflecting and absorbing structures that define the detector.

Spin-dependent quantum sensing is introduced through application of strong local magnetic field gradients within the detector: a core element of this project will be developing and testing superconducting microstructures for optimal spin selectivity.

The successful candidate will design and produce test samples in collaboration with academic and industrial partners in Heidelberg and Karlsruhe, and evaluate their performance through beamtime experiments at the FRM2 and other neutron centers (e.g., ILL and BNC).

Applications in polarized cold neutron scattering, sample environment design and optimisation, and precision measurements in neutron particle physics, may be pursued according to the background and interests of the candidate.