Fig. 1: Concept of the experiment.
From: Entangling Schrödinger’s cat states by bridging discrete- and continuous-variable encoding
a Seed-sprout analogy for our methods to create Bell–Cat states. In this analogy, the seeds represent Fock state encoding, the sprouts represent cat state encoding, water sprinkles represent two-photon pumps, and gray dotted curves indicate entanglement. b Bloch spheres for Fock state encoding and cat state encoding. The normalization factor was omitted for simplicity. c Figure of the chip. The left side is in false colour for clarity. Each KPO is composed of 10 direct-current superconducting quantum interference devices (DC SQUIDs) with a shunting capacitor. The two KPOs are capacitively coupled. The state of each KPO is monitored by the nearby transmon (green) and its readout resonator (purple). d Simultaneous and independent generation of even cat states \(\left\vert {0}_{{{{\rm{C}}}}}\right\rangle\) from vacuum states \(\left\vert {0}_{{{{\rm{F}}}}}\right\rangle\) and the corresponding pulse sequence. The pulse sequence used to measure the Wigner function is omitted for simplicity (see Supplementary Fig. 2 for the full pulse sequence). The colour represents the scaled one-mode Wigner function (1WF), i.e., the number parity.
