W-cat state realization in a multimode superconducting cavity architecture - Part 2

Multimode entanglement is a valuable resource for various quantum information tasks. In this work, we realize a tripartite entanglement in the form of a macroscopic W-state using a bosonic cqed architecture. Our system consists of three tantalum planar resonators as high-Q storage modes, collectively coupled to a single ancillary transmon. We develop an extension to the ECD (Echo Conditional Displacement) gate that leverages the higher ancilla levels to effectively create the W-state. Finally, we characterise the resulting state by probing 64 distinct points of the three-mode characteristic function. This implementation lays the groundwork for further exploration of W-states in quantum networking, quantum teleportation, and entanglement at the quantum-classical boundary.

In part 2 of the talk, we will discuss the key operations involved in the W-state creation scheme and detail how we leverage the coherent state encoding to perform full tomography using characteristic function measurements.