Optimal superpositions for particle detection via quantum phase
Eva Kilian, Marko Toroš, P. F. Barker, Sougato Bose · Physical Review Research · 2024
Exploiting quantum mechanics for sensing offers unprecedented possibilities. State-of-the-art proposals for novel quantum sensors often rely on the creation of large superpositions and generally detect a field. However, what is the optimal superposition size for detecting an incident particle from a specific direction? This question is nontrivial as, in general, this incident particle will scatter off with varied momenta, imparting varied recoils to the sensor, resulting in decoherence rather than a well-defined measurable phase. By considering scattering interactions of directional particulate environments with a system in a quantum superposition, we find that there is an optimal superposition size for measuring particles via a relative phase. As a consequence of the anisotropy of the environment, we observe a feature in the limiting behavior of the real and imaginary parts of the system's density matrix, linking the optimality of the superposition size to the wavelength of the scatterer. Published by the American Physical Society 2024