Characterization of a 16-Qubit Superconducting Device with Low-Crosstalk and Nearest-Neighbour Coupling

Scaling up superconducting quantum circuits encounters challenges such as Josephson-junction fabrication yield, design frequency targeting, and the appearance of spurious microwave modes in larger-scale devices. In this talk, we present the characterization of a 4x4 square lattice of 16 fixed frequency transmon qubits with nearest-neighbour capacitive coupling, demonstrating low crosstalk and single-qubit gate errors across the device. We realize this device in a tileable 3D-integrated circuit architecture [1] which has previously been shown to support high coherence and low crosstalk [2] and is expected to maintain performance at larger scales due to its simplicity and the use of off-chip inductive shunting to eliminate spurious enclosure modes [3]. We will discuss the design and fabrication process of the device, and show measurements of qubit coherence, single and two-qubit gates, and inter-qubit couplings across the lattice.

[1] Rahamim et al., Appl. Phys. Lett. 110, 222602 (2017)

[2] Spring et al. Science Advances 8.16 (2022): eabl6698

[3] Spring et al., Phys. Rev. Appl. 14, 024061 (2020)