Spin cat-state family for Heisenberg-limit metrology

Abstract

We identify a class of superposition spin coherent states that enable measurements with a Heisenberg-limit (HL) precision. We demonstrate that a superposition of any two antipodal points on the Bloch sphere (two antipodal spin coherent states) can provide the HL precision. This finding suggests a universal strategy for the generation of quantum states for HL metrology and offers a physically clear perspective on the relation between the HL precision and two-mode cat states. We show that antipodal cat states suitable for HL metrology can be generated using cavity quantum electrodynamics structures.