Spin-squeezed state generation using dipole-coupled spins

Spins in solids and molecules are promising for applications of quantum sensing technology. The sensitivity of the quantum sensing depends on how precisely spin observables can be determined in the measurement, and is intrinsically limited by the uncertainties of the observables. The use of a spin-squeezed state in a quantum sensor can reduce the uncertainty below the standard quantum limit when combined with an appropriate measurement procedure. Here, we discuss the simulation study of the generation of a squeezed state in an interacting spin system [1]. We show that a spin system coupled by the magnetic dipole interaction can create a squeezed state. Model systems to realize the spin squeezing experimentally are also discussed. In addition, we find that a squeezed state is a type of entangled state. Moreover, we discuss the experimental implementation of a spin-squeezed state in the nitrogen-vacancy center in diamond. This work highlights the potential of NV-center spin as a solid-state platform for quantum-enhanced metrology and nanoscale quantum sensing.