001014281 001__ 1014281 001014281 005__ 20231130201843.0 001014281 0247_ $$2datacite_doi$$a10.34734/FZJ-2023-03211 001014281 037__ $$aFZJ-2023-03211 001014281 041__ $$aEnglish 001014281 1001_ $$0P:(DE-Juel1)167542$$aWillsch, Dennis$$b0$$eCorresponding author$$ufzj 001014281 1112_ $$aIBM Qiskit Seminar$$cOnline$$wUSA 001014281 245__ $$aObservation of Josephson Harmonics in Tunnel Junctions$$f2023-08-25 - 001014281 260__ $$c2023 001014281 3367_ $$033$$2EndNote$$aConference Paper 001014281 3367_ $$2DataCite$$aOther 001014281 3367_ $$2BibTeX$$aINPROCEEDINGS 001014281 3367_ $$2ORCID$$aLECTURE_SPEECH 001014281 3367_ $$0PUB:(DE-HGF)31$$2PUB:(DE-HGF)$$aTalk (non-conference)$$btalk$$mtalk$$s1701327585_8565$$xInvited 001014281 3367_ $$2DINI$$aOther 001014281 520__ $$aSuperconducting quantum processors have a long road ahead to reach fault-tolerant quantum computing. One of the most daunting challenges is taming the numerous microscopic degrees of freedom ubiquitous in solid-state devices. State-of-the-art technologies, including the world's largest quantum processors, employ aluminum oxide (AlOx) tunnel Josephson junctions (JJs) as sources of nonlinearity, assuming an idealized pure sin(phi) current-phase relation (CPR). However, this celebrated sin(phi) CPR is only expected to occur in the unrealistic limit of vanishingly low-transparency channels in the AlOx barrier. Here we show that the standard CPR fails to describe the energy spectra of transmon artificial atoms across various samples and laboratories. Instead, a mesoscopic model of tunneling through an inhomogeneous AlOx barrier predicts %-level contributions from higher Josephson harmonics.By including these in the transmon Hamiltonian, we obtain orders of magnitude better agreement between the computed and measured energy spectra. The reality of Josephson harmonics transforms qubit design and prompts a reevaluation of models for quantum gates, parametric amplification and mixing, Floquet qubits, protected Josephson Rhombus chains, etc. Indeed, we show that engineered Josephson harmonics can reduce the charge dispersion and the associated errors in transmon qubits by an order of magnitude. 001014281 536__ $$0G:(DE-HGF)POF4-5111$$a5111 - Domain-Specific Simulation & Data Life Cycle Labs (SDLs) and Research Groups (POF4-511)$$cPOF4-511$$fPOF IV$$x0 001014281 536__ $$0G:(DE-Juel1)BMBF-13N16149$$aBMBF 13N16149 - QSolid (BMBF-13N16149)$$cBMBF-13N16149$$x1 001014281 7001_ $$0P:(DE-HGF)0$$aRieger, Dennis$$b1 001014281 7001_ $$0P:(DE-HGF)0$$aPop, Ioan$$b2 001014281 8564_ $$uhttps://www.youtube.com/watch?v=dWu3lCwyXBM 001014281 8564_ $$uhttps://juser.fz-juelich.de/record/1014281/files/Observation-of-Josephson-Harmonics-in-Tunnel-Junctions.pdf$$yOpenAccess 001014281 909CO $$ooai:juser.fz-juelich.de:1014281$$pdriver$$pVDB$$popen_access$$popenaire 001014281 9101_ $$0I:(DE-588b)5008462-8$$6P:(DE-Juel1)167542$$aForschungszentrum Jülich$$b0$$kFZJ 001014281 9131_ $$0G:(DE-HGF)POF4-511$$1G:(DE-HGF)POF4-510$$2G:(DE-HGF)POF4-500$$3G:(DE-HGF)POF4$$4G:(DE-HGF)POF$$9G:(DE-HGF)POF4-5111$$aDE-HGF$$bKey Technologies$$lEngineering Digital Futures – Supercomputing, Data Management and Information Security for Knowledge and Action$$vEnabling Computational- & Data-Intensive Science and Engineering$$x0 001014281 9141_ $$y2023 001014281 915__ $$0StatID:(DE-HGF)0510$$2StatID$$aOpenAccess 001014281 920__ $$lyes 001014281 9201_ $$0I:(DE-Juel1)JSC-20090406$$kJSC$$lJülich Supercomputing Center$$x0 001014281 980__ $$atalk 001014281 980__ $$aVDB 001014281 980__ $$aUNRESTRICTED 001014281 980__ $$aI:(DE-Juel1)JSC-20090406 001014281 9801_ $$aFullTexts