Spurious mode suppression in inductively shunted enclosures for large superconducting quantum devices

Embedding superconducting quantum circuits in enclosures with a clean electromagnetic environment is a key factor in maintaining high qubit performance. As devices are scaled up in size, the electromagnetic modes of sufficiently large enclosures will appear at low enough frequencies to interfere with the qubit and resonator modes of interest, reducing coherence and causing long-range crosstalk. Introducing an array of inductive shunts to an enclosure results in a cut-off frequency which is independent of its lateral size, exponentially suppressing enclosure-mediated qubit crosstalk at arbitrary chip size [1]. Here, we present simulations and measurements of enclosures large enough to hold a 16-qubit device, demonstrating suppression of the enclosure modes when inductively shunting pillars are included. These results are a promising indicator that this architecture will maintain the previously achieved high qubit performance [2] as these devices are scaled up.

 

[1] P. A. Spring et al., Phys. Rev. Appl. 14, 24061 (2020)

[2] P. A. Spring et al., arXiv:2107.11140 [quant-ph] (2021)