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A method for building low loss multi-layer wiring for superconducting microwave devices

Authors :
Josh Mutus
E. Lucero
Chris Quintana
James Wenner
Julian Kelly
Daniel Sank
Anthony Megrant
Zijun Chen
Matthew Neeley
Brooks Foxen
Evan Jeffrey
Charles Neill
Yu Chen
Amit Vainsencher
Paul V. Klimov
Andrew Dunsworth
John M. Martinis
Ted White
Ben Chiaro
Rami Barends
Pedram Roushan
Hartmut Neven
Austin G. Fowler
Source :
Applied Physics Letters. 112:063502
Publication Year :
2018
Publisher :
AIP Publishing, 2018.

Abstract

Complex integrated circuits require multiple wiring layers. In complementary metal-oxide-semiconductor processing, these layers are robustly separated by amorphous dielectrics. These dielectrics would dominate energy loss in superconducting integrated circuits. Here, we describe a procedure that capitalizes on the structural benefits of inter-layer dielectrics during fabrication and mitigates the added loss. We use a deposited inter-layer dielectric throughout fabrication and then etch it away post-fabrication. This technique is compatible with foundry level processing and can be generalized to make many different forms of low-loss wiring. We use this technique to create freestanding aluminum vacuum gap crossovers (airbridges). We characterize the added capacitive loss of these airbridges by connecting ground planes over microwave frequency λ/4 coplanar waveguide resonators and measuring resonator loss. We measure a low power resonator loss of ∼3.9 × 10−8 per bridge, which is 100 times lower than that of dielectric supported bridges. We further characterize these airbridges as crossovers, control line jumpers, and as part of a coupling network in gmon and fluxmon qubits. We measure qubit characteristic lifetimes (T1s) in excess of 30 μs in gmon devices.

Details

ISSN :
10773118 and 00036951
Volume :
112
Database :
OpenAIRE
Journal :
Applied Physics Letters
Accession number :
edsair.doi...........15a2c43a2d746f32654671982996cea1
Full Text :
https://doi.org/10.1063/1.5014033