Non-local detection of coherent Yu–Shiba–Rusinov quantum projections

Probing spatially confined quantum states from afar-a long-sought goal to minimize external interference-has been proposed to be feasible in condensed-matter systems through the coherent projection of the state. This can be achieved by engineering the eigenstates of the electron sea that surrounds the quantum state using cages built atom by atom, the so-called quantum corrals. However, the demonstration of the coherent nature of the projection and manipulation of its quantum composition are still important goals. Here we show this for the coherent projection of a Yu-Shiba-Rusinov quantum state that is induced by a magnetic impurity, using the eigenmodes of corrals on the surface of a superconductor. This enables us to manipulate the particle-hole composition of the projected state by tuning the corral eigenmodes through the Fermi energy. Our results demonstrate a controlled non-local method for the detection of magnet-superconductor hybrid quantum states.