Fig. 4

Hybridized normal modes. a The schematic showing the wavefunctions of the coupled system involving the communication resonators and the coaxial cable. The three degenerate modes hybridize and form three normal modes with distinct signatures. The center normal mode has minimal participation in the lossy cable mode and has high-quality factor. b Stimulated vacuum Rabi oscillations around the communication modes. The near-degeneracy of the coaxial cable with the two communication resonators give rise to this almost equally-spaced three-mode structure. Being the two bright modes that include the lossy cable mode, and the dark “communication” mode of the two resonators. The latter couples more strongly to both qubits, and has a lifetime that is ideally only limited by the internal quality factors of the communication resonators. By fitting the simulation to experimental data, we found that the coaxial cable has a slightly higher frequency than the on-chip communication resonators [see Appendix]. c., d T₁ and \(T_2^ \ast\) data of the communication mode. The coherence time of the communication mode is characterized through protocols analogous to those for the transmon. We characterize both T₁ and \(T_2^ \ast\) of the communication mode, and find T₁ = 550 ns and \(T_2^ \ast = 1\,\mu s\)