Suppression of quasiparticle poisoning in transmon qubits by gap engineering

Journal Article · Tue Sep 05 04:00:00 EDT 2023 · TBD

OSTI ID:2246735

Kamenov, Plamen ^[1]; DiNapoli, Thomas J. ^[1]; Gershenson, Michael ^[1]; Chakram, Srivatsan ^[1]

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1. Rutgers U., Piscataway

The performance of various superconducting devices operating at ultra-low temperatures is impaired by the presence of non-equilibrium quasiparticles. Inelastic quasiparticle (QP) tunneling across Josephson junctions in superconducting qubits results in decoherence and spurious excitations and, notably, can trigger correlated errors that severely impede quantum error correction. In this work, we use "gap engineering" to suppress the tunneling of low-energy quasiparticles in Al-based transmon qubits, a leading building block for superconducting quantum processors. By implementing potential barriers for QP, we strongly suppress QP tunneling across the junction and preserve charge parity for over $10^3$ seconds. The suppression of QP tunneling also results in a reduction in the qubit energy relaxation rates. The demonstrated approach to gap engineering can be easily implemented in all Al-based circuits with Josephson junctions.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 2246735
• Report Number(s): FERMILAB-PUB-23-497-SQMS-V; arXiv:2309.02655; oai:inspirehep.net:2694051
• Journal Information: TBD, Journal Name: TBD
• Country of Publication: United States
• Language: English