Ryan Babbush

Ryan after PhD Defense

Dr. Ryan Babbush

Senior Research Scientist
Google, Quantum A.I. Lab

Email: babbush [at] google
Phone: (949) 331-3943


Ph.D. Chemical Physics, Harvard University. 2015.
M.A. Physics, Harvard University. 2013.
B.A. Physics & Chemistry, Carleton College. 2011.

Research Interests
  • Development of quantum simulation algorithms, especially with applications in electronic structure theory.
  • Methods of compiling Hamiltonians for quantum annealing and universal adiabatic quantum computing.
  • Machine learning, especially problems pertaining to probabilistic graphical models and neural networks.
  • Founder and lead developer of the open source project OpenFermion (www.openfermion.org/).

Google Scholar Profile

33.  Ryan Babbush, Dominic Berry, and Hartmut Neven. Quantum Simulation of the Sachdev-Ye-Kitaev Model by Asymmetric Qubitization.
       arXiv preprint: 1806.02793. 1-5. 2018.

32.  Ryan Babbush, Craig Gidney, Dominic Berry, Nathan Wiebe Jarrod McClean, Alexandru Paler, Austin Fowler and Hartmut Neven.
       Encoding Electronic Spectra in Quantum Circuits with Linear T Complexity. arXiv preprint: 1805.03662. 1-39. 2018.

31.  Nicholas Rubin, Ryan Babbush and Jarrod McClean. Application of Fermionic Marginal Constraints to Hybrid Quantum Algorithms.
       New Journal of Physics. Volume 20, Number 5: 053020. 2018.

30.  Dominic Berry, Mária Kieferová, Artur Scherer, Yuval Sanders, Guang Hao Low, Nathan Wiebe, Craig Gidney and Ryan Babbush.
       Improved Techniques for Preparing Eigenstates of Fermionic Hamiltonians. npj Quantum Information. Volume 4, Number 1: 22. 2018.

29.  Sergio Boixo, Sergei Isakov, Vadim Smelyanskiy, Ryan Babbush, Nan Ding, Zhang Jiang, Michael Bremner, John Martinis,
       and Hartmut Neven. Characterizing Quantum Supremacy in Near-Term Devices. Nature Physics. Volume 14: 595–600. 2018.
       Press Release.

28.  Jarrod McClean, Sergio Boixo, Vadim Smelyanskiy, Ryan Babbush and Hartmut Neven.
       Barren Plateaus in Quantum Neural Network Training Landscapes. arXiv preprint: 1803.11173. 1-7. 2018.

27.  Cornelius Hempel, Christine Maier, Jonathan Romero, Jarrod McClean, Thomas Monz, Heng Shen, Petar Jurcevic,
       Ben Lanyon, Peter Love, Ryan Babbush, Alán Aspuru-Guzik, Rainer Blatt and Christian Roos.
       Quantum Chemistry Calculations on a Trapped-Ion Quantum Simulator. arXiv preprint: 1803.10238. 1-21. 2018.

26.  Ryan Babbush, Nathan Wiebe, Jarrod McClean, James McClain, Hartmut Neven and Garnet Kin-Lic Chan.
       Low-Depth Quantum Simulation of Materials. Physical Review X. Volume 8, Number 1: 011044. 2018. Press Release.

25.  Ian Kivlichan, Jarrod McClean, Nathan Wiebe, Craig Gidney, Alán Aspuru-Guzik, Garnet Kin-Lic Chan and Ryan Babbush.
       Quantum Simulation of Electronic Structure with Linear Depth and Connectivity. Physical Review Letters.
       Volume 120, Number 11: 110501. 2018. Press Release.

24.  J. McClean, I. Kivlichan, K. Sung, D. Steiger, Y. Cao, C. Dai, E. Fried, C. Gidney, B. Gimby, P. Gokhale, T. Häner, T. Hardikar,
       V. Havlíček, C. Huang, Z. Jiang, M. Neeley, T. O’Brien, I. Ozfidan, M. Radin, J. Romero, N. Rubin, N. Sawaya, K. Setia,
       S. Sim, M. Steudtner, Q. Sun, W. Sun, F. Zhang and R. Babbush. OpenFermion: The Electronic Structure Package
       for Quantum Computers
. arXiv preprint: 1710.07629. 2017. Press Release. GitHub.

23.  Ian Kivlichan, Nathan Wiebe, Ryan Babbush and Alán Aspuru-Guzik. Bounding the Costs of Quantum Simulation
       of Many-Body Physics in Real Space
. Journal of Physics A. Volume 50, Number 30: 305301. 2017.

22.  Masoud Mohseni, Peter Read, Hartmut Neven, Sergio Boixo, Vasil Denchev, Ryan Babbush, Austin Fowler,
       Vadim Smelyanskiy and John Martinis. Commercialize Quantum Technologies in Five Years.
       Nature. Volume 543, Number 7644: 171–174. 2017.

21.  P. Roushan, C. Neill, A. Megrant, Y. Chen, R. Babbush, R. Barends, B. Campbell, Z. Chen, B. Chiaro, A. Dunsworth, A. Fowler,
       E. Jeffrey, J. Kelly, E. Lucero, J. Mutus, P. O’Malley, M. Neeley, C. Quintana, D. Sank, A. Vainsencher, J. Wenner, T. White,
       E. Kapit and J. Martinis. Chiral Ground-State Currents of Interacting Photons in a Synthetic Magnetic Field.
       Nature Physics. Volume 13, Number 2: 146–151. 2017. Journal Cover.

20.  Ryan Babbush, Dominic Berry, Yuval Sanders, Ian Kivlichan, Artur Scherer, Annie Wei, Peter Love and Alán Aspuru-Guzik.
       Exponentially More Precise Quantum Simulation of Fermions in the Configuration Interaction Representation
       Quantum Science and Technology. Volume 3, Number 1: 015006. 2018.

19.  Jonathan Romero, Ryan Babbush, Jarrod McClean, Cornelius Hempel, Peter Love and Alán Aspuru-Guzik.
       Strategies for Quantum Computing Molecular Energies Using the Unitary Coupled Cluster Ansatz.
       arXiv preprint 1701.02691. 1-18. 2017.

18.  Vasil Denchev, Sergio Boixo, Sergei Isakov, Nan Ding, Ryan Babbush, Vadim Smelyanskiy, John Martinis and Hartmut Neven.
       What is the Computational Value of Finite Range Tunneling? Physical Review X. Volume 6, Number 3: 031015. 2016. Press Release.

17.  [P. O'Malley, R. Babbush]*, I. Kivlichan, J. Romero, J. McClean, R. Barends, J. Kelly, P. Roushan, A. Tranter, N. Ding,
       B. Campbell, Y. Chen, Z. Chen, B. Chiaro, A. Dunsworth, A. Fowler, E. Jeffrey, A. Megrant, J. Mutus, C. Neill, C. Quintana,
       D. Sank, A. Vainsencher, J. Wenner, T. White, P. Coveny, P. Love, H. Neven, A. Aspuru-Guzik and J. Martinis.
       Scalable Quantum Simulation of Molecular Energies. Physical Review X. Volume 6, Number 3: 031007. 2016.
       *Both authors contributed equally. Press Release.

16.  R. Barends, A. Shabani, L. Lamata, J. Kelly, A. Mezzacapo, U. Las Heras, R. Babbush, A. Fowler, B. Campbell,
       Y. Chen, Z. Chen, B. Chiaro, A. Dunsworth, E. Jeffrey, E. Lucero, A. Megrant, J. Mutus, M. Neeley, C. Neill, P. O’Malley,
       C. Quintana, P. Roushan, D. Sank, A. Vainsencher, J. Wenner, T. White, E. Solano, H. Neven and J. Martinis.
       Digitized Adiabatic Quantum Computing with a Superconducting Circuit. Nature. Volume 534, Number 7606: 222-226. 2016.
       Press Release.

15.  Ryan Babbush, Dominic Berry, Ian Kivlichan, Annie Wei, Peter Love and Alán Aspuru-Guzik. Exponentially More Precise
       Quantum Simulation of Fermions in Second Quantization
. New Journal of Physics. Volume 18, Number 3: 033032. 2016.

14.  Jarrod McClean, Jonathan Romero, Ryan Babbush and Alán Aspuru-Guzik. The Theory of Variational Hybrid
       Quantum-Classical Algorithms
. New Journal of Physics. Volume 18, Number 2: 023023. 2016.

13.  Andrew Tranter, Sarah So fia, Jacob Seeley, Michael Kaicher, Jarrod McClean, Ryan Babbush, Peter Coveney,
       Florian Mintert, Frank Wilhelm and Peter Love. The Bravyi-Kitaev Transformation: Properties and Applications.
International Journal of Quantum Chemistry. Volume 115, Number 19: 1431-1441. 2015.

12.  Ryan Babbush, Jarrod McClean, Dave Wecker, Alán Aspuru-Guzik and Nathan Wiebe. Chemical Basis of Trotter-Suzuki
       Errors in Quantum Chemistry Simulation.
Physical Review A. Volume 91, Number 2: 022311. 2015.

11.  Yudong Cao, Ryan Babbush, Jacob Biamonte, and Sabre Kais. Hamiltonian Gadgets with Reduced Resource Requirements.
       Physical Review A. Volume 91, Number 1: 012315. 2015.

10.  Bryan O’Gorman, Alejandro Perdomo-Ortiz, Ryan Babbush, Alán Aspuru-Guzik and Vadim Smelyanskiy. Bayesian Network
       Structure Learning using Quantum Annealing
. European Physical Journal. Volume 224, Number 1: 163-188. 2015.

9.   Ya Wang, Florian Dolde, Jacob Biamonte, Ryan Babbush, Ville Bergholm, Sen Yang, Ingmar Jakobi, Philipp Neumann, Alán
      Aspuru-Guzik, James D. Whitfield and Jörg Wrachtrup. Quantum Simulation of Helium Hydride Cation in a Solid-State Spin Register.
      ACS Nano. Volume 9, Number 8: 7769–7774. 2015.

8.   Nan Ding, Youhan Fang, Ryan Babbush, Changyou Chen, Robert Skeel and Hartmut Neven. Bayesian Sampling Using
      Stochastic Gradient Thermostats
. Advances in Neural Information Processing Systems. Volume 27: 3203-3211. 2014.

7.   Jarrod R. McClean, Ryan Babbush, Peter J. Love and Alán Aspuru-Guzik. Exploiting Locality in Quantum Computation for
      Quantum Chemistry
. The Journal of Physical Chemistry Letters. Volume 5, Number 24: 4368–4380. 2014.

6.   Ryan Babbush, Vasil Denchev, Nan Ding, Sergei Isakov and Hartmut Neven. Construction of Non-Convex Polynomial Loss
      Functions for Training a Binary Classifier with Quantum Annealing
. arXiv preprint 1406.4203. 1-15. 2014.

5.   Ryan Babbush, Peter Love, and Alán Aspuru-Guzik. Adiabatic Quantum Simulation of Quantum Chemistry.
      Scientific Reports. Volume 4, Number 6603: 1-11. 2014.

4.   Ryan Babbush, Alejandro Perdomo-Ortiz, Bryan O’Gorman, William Macready, and Alán Aspuru-Guzik. Construction of Energy
      Functions for Lattice Heteropolymer Models: Efficient Encodings for Constraint Satisfaction Programming and Quantum Annealing
      Advances in Chemical Physics. Volume 155, Chapter 5: 201-243. 2014.

3.   Ryan Babbush, Bryan O’Gorman, and Alán Aspuru-Guzik. Resource Efficient Gadgets for Compiling Adiabatic Quantum
      Optimization Problems
. Annalen der Physik. Volume 525, Number 10-11: 877–888. 2013.

2.   Ryan Babbush, John Parkhill, and Alán Aspuru-Guzik. Force-Field Functor Theory: Classical Force-Fields which Reproduce
      Equilibrium Quantum Distributions
. Frontiers in Chemistry. Volume 1, Number 26: 1-10. 2013.

1.   Ari Zeida, Ryan Babbush, Mariano Camilo González Lebrero, Madia Trujillo, Rafael Radi, and Darío Estrin. Molecular Basis of the
      Mechanism of Thiol Oxidation by Peroxides in Aqueous Solution: Challenging the SN2 Paradigm
. ACS Toxicology.
      Volume 25, Number 3: 741-746. 2012.