Dissipative quantum sensing via magnetic domain wall qubits

Magnetic domain walls are a fundamental building block in the field of spintronics, playing a key role in classical information storage.  Recently, interest in quantum domain walls has become a subject of interest for quantum information, leading to the concept of the domain wall qubit.  We study the utility of domain wall qubits for sensing magnetic field noise via dissipative dynamics.  We demonstrate that the domain wall qubit realizes a cat state that amplifies the effects of decoherence and we compute the resulting  quantum Fisher information.  Remarkably, the optimal sensing protocol requires a sequence of short time measurements.  Our work has significant implications in the broader context of dissipative quantum sensing and quantum state preparation via topological means.