Julian S. Kelly

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Julian S. Kelly
1988 (age 35–36)
NationalityUnited States
CitizenshipUnited States
Alma materUniversity of California, Santa Barbara (Bachelor of Science),
University of California, Santa Barbara (Doctor of Philosophy)
Scientific career
FieldsPhysics, Quantum Computing
  • Google
  • University of California, Santa Barbara
Doctoral advisorJohn M. Martinis

Julian S. Kelly (born 1988) is the Director of Quantum Hardware at Quantum Artificial Intelligence Lab.[1][2] He leads teams that are focused on building an error-corrected quantum computer in Santa Barbara, California.


Kelly obtained his Bachelor of Science degree in Physics at University of California, Santa Barbara in 2010. As part of his studies, Kelly completed an undergraduate thesis and publication for his work on the calibration of superconducting phase qubits for quantum computation.[3][4] He remained at the same university and completed his PhD in 2015 under the supervision of John M. Martinis building superconducting devices for quantum computation.[5] The title of his dissertation was "Fault-tolerant superconducting qubits".[6] During his PhD, Kelly experimentally showed high coherence tunable superconducting "Xmon" transmon qubits that can be laid out in a two-dimensional architecture for quantum computation. Kelly also showed the first high-fidelity gates between two superconducting qubits with fidelity greater than 99% as well as calibration techniques used to achieve them.[7] Additionally, Kelly experimentally showed the reduction of bit-flip errors in a linear chain of multiple qubits compared to individual qubits by tracking these errors through repeated measurements using Quantum error correction.[8] These works established superconducting qubits as a viable platform for building quantum computers, and formed the foundation for work that is being pursued at various research groups.


Following his PhD, Kelly joined Google as a Research Scientist.[9] As part of the team, Kelly contributed to the experimental techniques for automated calibration of the quantum computers built by Google.[10][11][12] In addition, Kelly was the lead designer of the Bristlecone quantum processor, a fully two-dimensional integrated superconducting quantum processor and largest gate-based system at its time with 72 qubits.[13] Bristlecone was also the foundation for the Sycamore processor, which was used to demonstrate a quantum computer outperforming a classical computer.[14] Kelly holds various patents and has published extensively on experimental implementations of quantum computation using superconducting qubits.[15]


  1. "Julian Kelly - Google Research". research.google. 20 February 2023.
  2. "Discover the Quantum AI campus". Google Quantum AI. Retrieved 2023-02-21.
  3. "Phys. Rev. A. 82, 042339 (2010) Reduced phase error through optimized control of a superconducting qubit". journals.aps.org. 20 February 2023.
  4. "Kelly2010.pdf" (PDF). web.physics.ucsb.edu. 20 February 2023.
  5. "Kelly2015.pdf" (PDF). web.physics.ucsb.edu. 20 February 2023.
  6. Kelly, Julian (2015). Fault-tolerant superconducting qubits (Thesis). UC Santa Barbara.
  7. "Kelly2015.pdf" (PDF). web.physics.ucsb.edu. 20 February 2023.
  8. "Kelly2015.pdf" (PDF). web.physics.ucsb.edu. 20 February 2023.
  9. Lardinois, Frederic (2014-09-02). "Google Partners With UCSB To Build Quantum Processors For Artificial Intelligence". TechCrunch. Retrieved 2023-02-21.
  10. Kelly, Julian; O'Malley, Peter; Neeley, Matthew; Neven, Hartmut; Martinis, John M. (2018-03-08). "Physical qubit calibration on a directed acyclic graph". arXiv:1803.03226 [quant-ph].
  11. Klimov, Paul V.; Kelly, Julian; Martinis, John M.; Neven, Hartmut (2020-06-08). "The Snake Optimizer for Learning Quantum Processor Control Parameters". arXiv:2006.04594 [quant-ph].
  12. Automating qubit calibration in superconducting quantum processors, retrieved 2023-02-21
  13. "List of quantum processors", Wikipedia, 2023-02-20, retrieved 2023-02-21
  14. Arute, Frank; Arya, Kunal; Babbush, Ryan; Bacon, Dave; Bardin, Joseph C.; Barends, Rami; Biswas, Rupak; Boixo, Sergio; Brandao, Fernando G. S. L.; Buell, David A.; Burkett, Brian; Chen, Yu; Chen, Zijun; Chiaro, Ben; Collins, Roberto (October 2019). "Quantum supremacy using a programmable superconducting processor". Nature. 574 (7779): 505–510. doi:10.1038/s41586-019-1666-5. ISSN 1476-4687.
  15. "Julian Kelly". scholar.google.com. Retrieved 2023-02-21.

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