Precision measurements using squeezed spin states via two-axis countertwisting interactions
Emi Yukawa, Gerard J Milburn, Catherine A. Holmes, Masahito Ueda, Kae Nemoto · Physical Review A · 2014
We show that the two-axis countertwisting interaction squeezes a coherent spin state into three states of interest in quantum information, namely, the equally weighted superposition state, the state close to the twin-Fock state, and the state achieving the Heisenberg limit of optimal sensitivity defined by the Cram\'er-Rao inequality, in addition to the well-known Heisenberg-limited state of spin fluctuations.