A ring-resonator based coupler with tunability for on-demand connectivity in a superconducting multi-qubit network*

Recently, we demonstrated a ring-resonator based architecture in 3D cQED [1] for enhanced connectivity in a superconducting multi-qubit network without compromising coupling uniformity. This design can be extended to build highly connected processors using large number of qubits. However, building processors with always-on inter-qubit coupling can lead to coherent errors due to several connected spectator qubits.  Introducing tunable couplers can enable activation of coupling on demand between a subset of qubits within a larger network. This reduces unwanted crosstalk and offers flexibility for different applications.

Here, we present our progress towards realizing a ring-resonator based coupler with tunability. The design uses tunable couplers between each qubit and the ring-resonator in the 2D cQED architecture to enable flux-based tuning. We will discuss the design and optimization of our coupler using simulations and present preliminary experimental data characterizing device performance.

[1] S.Hazra, A.Bhattacharjee, et.al. Phys. Rev. Applied 16, 024018 (2021)