Fig. 2: Converting Bell–Fock states to Bell–Cat states.
From: Entangling Schrödinger’s cat states by bridging discrete- and continuous-variable encoding
a Rabi oscillations for Bell-preparation pulse. Regarding Rabi oscillations associated with \(\left\vert {0}_{{{{\rm{F}}}}}{1}_{{{{\rm{F}}}}}\right\rangle \leftrightarrow \left\vert {1}_{{{{\rm{F}}}}}{0}_{{{{\rm{F}}}}}\right\rangle\) transitions, the colour represents the population of the \(\left\vert {0}_{{{{\rm{F}}}}}\right\rangle\) state of KPO2 and zero detuning corresponds to the frequency ωK1 − ωK2. As for Rabi oscillations associated with \(\left\vert {0}_{{{{\rm{F}}}}}{0}_{{{{\rm{F}}}}}\right\rangle \leftrightarrow \left\vert {1}_{{{{\rm{F}}}}}{1}_{{{{\rm{F}}}}}\right\rangle\) transitions, the colour represents the population of the \(\left\vert {0}_{{{{\rm{F}}}}}\right\rangle\) state of KPO1 and zero detuning corresponds to the frequency ωK1 + ωK2 − ΔAC, where ΔAC is an AC Stark-like frequency shift whose value is 21 MHz in this measurement. b Measured one-mode Wigner function (1WF) of Bell–Fock and Bell–Cat states. c Pulse sequences for Bell–Fock state preparation and Bell–Cat state generation. The amplitude and length of pulses are not to scale. d, e Measured two-mode Wigner function (2WF) for Bell–Fock (d) and Bell–Cat (e) states. In Re–Re plots, \({{{\rm{Im}}}}({\alpha }_{1})={{{\rm{Im}}}}({\alpha }_{2})=0\), whereas in Im–Im plots, \({{{\rm{Re}}}}({\alpha }_{1})={{{\rm{Re}}}}({\alpha }_{2})=0\). The colour represents the joint number parity.
