Fig. 2: Mapping from Fock to cat.

a Bloch sphere for the Fock state encoding (left) and the cat state encoding (right). b Experimental demonstration of one-to-one mapping from Fock states to cat states. The profile of the pump pulse is shown by the colored solid line; the dotted line shows the counterdiabatic pulse. The scales of Re(α) and Im(α) in Fock state tomography are both ±1.6. The Wigner tomography of the \(\left|+{{{{{{{\rm{Cat}}}}}}}}\right\rangle\) state is intentionally rotated by adjusting the phase of the displacement pulse for an aesthetic reason. c Position of the classical energy minima α_c as a function of pump detuning [Δ in Eq. (1)]. The red solid line in the upper plot shows the theoretical values following the formula \({\alpha }_{{{{{{{{\rm{c}}}}}}}}}=\sqrt{(P+{{\Delta }})/K}\)¹⁰; the solid circles show the measured size of cat states. Error bars represent standard deviation; the errors in Δ are caused mainly by the slow drift of ω_K and frequent earthquakes in Japan. Wigner tomographies with three representative pump detunings are shown in the left part (before relaxation of quantum interference) and right part (after relaxation) of (c). The open black circles in the tomographies after relaxation indicate the classical energy minima.