Dave Bacon

Dave Bacon

Dave Bacon is a Senior Staff Software Engineer at Google. Prior to Google he was a research assistant professor at the University of Washington. His research interests include quantum computing and machine intelligence.
Authored Publications
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    Stable quantum-correlated many-body states through engineered dissipation
    Sara Shabani
    Dripto Debroy
    Jerome Lloyd
    Alexios Michailidis
    Andrew Dunsworth
    Bill Huggins
    Markus Hoffmann
    Alexis Morvan
    Josh Cogan
    Ben Curtin
    Guifre Vidal
    Bob Buckley
    Tom O'Brien
    John Mark Kreikebaum
    Rajeev Acharya
    Joonho Lee
    Ningfeng Zhu
    Shirin Montazeri
    Sergei Isakov
    Jamie Yao
    Clarke Smith
    Rebecca Potter
    Sean Harrington
    Jeremy Hilton
    Paula Heu
    Alexei Kitaev
    Alex Crook
    Fedor Kostritsa
    Kim Ming Lau
    Dmitry Abanin
    Trent Huang
    Aaron Shorter
    Steve Habegger
    Gina Bortoli
    Charles Rocque
    Vladimir Shvarts
    Alfredo Torres
    Anthony Megrant
    Charles Neill
    Michael Hamilton
    Dar Gilboa
    Lily Laws
    Nicholas Bushnell
    Ramis Movassagh
    Mike Shearn
    Wojtek Mruczkiewicz
    Desmond Chik
    Leonid Pryadko
    Xiao Mi
    Brooks Foxen
    Frank Arute
    Alejo Grajales Dau
    Yaxing Zhang
    Lara Faoro
    Alexander Lill
    JiunHow Ng
    Justin Iveland
    Marco Szalay
    Orion Martin
    Juhwan Yoo
    Michael Newman
    William Giang
    Alex Opremcak
    Amanda Mieszala
    William Courtney
    Andrey Klots
    Wayne Liu
    Pavel Laptev
    Charina Chou
    Paul Conner
    Rolando Somma
    Vadim Smelyanskiy
    Benjamin Chiaro
    Grayson Young
    Tim Burger
    ILYA Drozdov
    Agustin Di Paolo
    Jimmy Chen
    Marika Kieferova
    Michael Broughton
    Negar Saei
    Juan Atalaya
    Markus Ansmann
    Pavol Juhas
    Murray Ich Nguyen
    Yuri Lensky
    Roberto Collins
    Élie Genois
    Jindra Skruzny
    Igor Aleiner
    Yu Chen
    Reza Fatemi
    Leon Brill
    Ashley Huff
    Doug Strain
    Monica Hansen
    Noah Shutty
    Ebrahim Forati
    Dave Landhuis
    Kenny Lee
    Ping Yeh
    Kunal Arya
    Henry Schurkus
    Cheng Xing
    Cody Jones
    Edward Farhi
    Raja Gosula
    Andre Petukhov
    Alexander Korotkov
    Ani Nersisyan
    Christopher Schuster
    George Sterling
    Kostyantyn Kechedzhi
    Trond Andersen
    Alexandre Bourassa
    Kannan Sankaragomathi
    Vinicius Ferreira
    Science, 383 (2024), pp. 1332-1337
    Preview abstract Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-range quantum correlations and a ground-state fidelity of 0.86 for 18 qubits at the critical point. In two dimensions, we found mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we explored transport in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors. View details
    Dynamics of magnetization at infinite temperature in a Heisenberg spin chain
    Tomaž Prosen
    Vedika Khemani
    Rhine Samajdar
    Jesse Hoke
    Sarang Gopalakrishnan
    Andrew Dunsworth
    Bill Huggins
    Markus Hoffmann
    Alexis Morvan
    Josh Cogan
    Ben Curtin
    Guifre Vidal
    Bob Buckley
    Tom O'Brien
    John Mark Kreikebaum
    Rajeev Acharya
    Joonho Lee
    Ningfeng Zhu
    Shirin Montazeri
    Sergei Isakov
    Jamie Yao
    Clarke Smith
    Rebecca Potter
    Sean Harrington
    Jeremy Hilton
    Paula Heu
    Alexei Kitaev
    Alex Crook
    Fedor Kostritsa
    Kim Ming Lau
    Dmitry Abanin
    Trent Huang
    Aaron Shorter
    Steve Habegger
    Steven Martin
    Gina Bortoli
    Seun Omonije
    Richard Ross Allen
    Charles Rocque
    Vladimir Shvarts
    Alfredo Torres
    Anthony Megrant
    Charles Neill
    Michael Hamilton
    Dar Gilboa
    Lily Laws
    Nicholas Bushnell
    Kyle Anderson
    Ramis Movassagh
    David Rhodes
    Mike Shearn
    Wojtek Mruczkiewicz
    Desmond Chik
    Leonid Pryadko
    Xiao Mi
    Brooks Foxen
    Frank Arute
    Alejo Grajales Dau
    Yaxing Zhang
    Lara Faoro
    Alexander Lill
    Gordon Hill
    JiunHow Ng
    Justin Iveland
    Marco Szalay
    Orion Martin
    Juan Campero
    Juhwan Yoo
    Michael Newman
    William Giang
    Gonzalo Garcia
    Alex Opremcak
    Amanda Mieszala
    William Courtney
    Andrey Klots
    Wayne Liu
    Pavel Laptev
    Paul Conner
    Rolando Somma
    Vadim Smelyanskiy
    Benjamin Chiaro
    Grayson Young
    Tim Burger
    ILYA Drozdov
    Agustin Di Paolo
    Jimmy Chen
    Marika Kieferova
    Hung-Shen Chang
    Michael Broughton
    Negar Saei
    Juan Atalaya
    Markus Ansmann
    Pavol Juhas
    Murray Ich Nguyen
    Yuri Lensky
    Roberto Collins
    Élie Genois
    Jindra Skruzny
    Yu Chen
    Reza Fatemi
    Leon Brill
    Seneca Meeks
    Ashley Huff
    Doug Strain
    Monica Hansen
    Noah Shutty
    Ebrahim Forati
    Doug Thor
    Dave Landhuis
    Kenny Lee
    Ping Yeh
    Kunal Arya
    Henry Schurkus
    Cheng Xing
    Cody Jones
    Edward Farhi
    Vlad Sivak
    Raja Gosula
    Andre Petukhov
    Clint Earle
    Alexander Korotkov
    Ani Nersisyan
    Christopher Schuster
    George Sterling
    Trond Andersen
    Alexandre Bourassa
    Salvatore Mandra
    Kannan Sankaragomathi
    Vinicius Ferreira
    Science, 384 (2024), pp. 48-53
    Preview abstract Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the one-dimensional Heisenberg model were conjectured as to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we studied the probability distribution of the magnetization transferred across the chain’s center, P(M). The first two moments of P(M) show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments ruled out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide insights into universal behavior in quantum systems. View details
    Purification-Based Quantum Error Mitigation of Pair-Correlated Electron Simulations
    Christian Gogolin
    Vincent Elfving
    Fotios Gkritsis
    Oumarou Oumarou
    Gian-Luca R. Anselmetti
    Masoud Mohseni
    Andrew Dunsworth
    William J. Huggins
    Markus Rudolf Hoffmann
    Alexis Morvan
    Josh Godfrey Cogan
    Ben Curtin
    Guifre Vidal
    Bob Benjamin Buckley
    Trevor Johnathan Mccourt
    Thomas E O'Brien
    John Mark Kreikebaum
    Rajeev Acharya
    Joonho Lee
    Ningfeng Zhu
    Shirin Montazeri
    Sergei Isakov
    Jamie Yao
    Clarke Smith
    Rebecca Potter
    Sean Harrington
    Jeremy Patterson Hilton
    Alex Crook
    Fedor Kostritsa
    Kim Ming Lau
    Dmitry Abanin
    Trent Huang
    Aaron Shorter
    Steve Habegger
    Richard Ross Allen
    Vladimir Shvarts
    Alfredo Torres
    Stefano Polla
    Anthony Megrant
    Charles Neill
    Michael C. Hamilton
    Dar Gilboa
    Lily MeeKit Laws
    Nicholas Bushnell
    Kyle Anderson
    Ramis Movassagh
    Mike Shearn
    Wojtek Mruczkiewicz
    Desmond Chun Fung Chik
    Xiao Mi
    Brooks Riley Foxen
    Frank Carlton Arute
    Alejandro Grajales Dau
    Yaxing Zhang
    Lara Faoro
    Alexander T. Lill
    Jiun How Ng
    Justin Thomas Iveland
    Marco Szalay
    Orion Martin
    Juhwan Yoo
    Michael Newman
    William Giang
    Alex Opremcak
    William Courtney
    Andrey Klots
    Wayne Liu
    Pavel Laptev
    Paul Conner
    Rolando Diego Somma
    Vadim Smelyanskiy
    Benjamin Chiaro
    Grayson Robert Young
    Tim Burger
    Ilya Drozdov
    Jimmy Chen
    Marika Kieferova
    Michael Blythe Broughton
    Juan Atalaya
    Markus Ansmann
    Pavol Juhas
    Murray Nguyen
    Daniel Eppens
    Roberto Collins
    Jindra Skruzny
    Igor Aleiner
    Yu Chen
    Reza Fatemi
    Leon Brill
    Ashley Anne Huff
    Doug Strain
    Ebrahim Forati
    Dave Landhuis
    Kenny Lee
    Ping Yeh
    Kunal Arya
    Cody Jones
    Edward Farhi
    Andre Gregory Petukhov
    Alexander Korotkov
    Ani Nersisyan
    Christopher Schuster
    Kostyantyn Kechedzhi
    Trond Ikdahl Andersen
    Alexandre Bourassa
    Kannan Aryaperumal Sankaragomathi
    Nature Physics (2023)
    Preview abstract An important measure of the development of quantum computing platforms has been the simulation of increasingly complex physical systems. Prior to fault-tolerant quantum computing, robust error mitigation strategies are necessary to continue this growth. Here, we study physical simulation within the seniority-zero electron pairing subspace, which affords both a computational stepping stone to a fully correlated model, and an opportunity to validate recently introduced ``purification-based'' error-mitigation strategies. We compare the performance of error mitigation based on doubling quantum resources in time (echo verification) or in space (virtual distillation), on up to 20 qubits of a superconducting qubit quantum processor. We observe a reduction of error by one to two orders of magnitude below less sophisticated techniques (e.g. post-selection); the gain from error mitigation is seen to increase with the system size. Employing these error mitigation strategies enables the implementation of the largest variational algorithm for a correlated chemistry system to-date. Extrapolating performance from these results allows us to estimate minimum requirements for a beyond-classical simulation of electronic structure. We find that, despite the impressive gains from purification-based error mitigation, significant hardware improvements will be required for classically intractable variational chemistry simulations. View details
    Measurement-induced entanglement and teleportation on a noisy quantum processor
    Vedika Khemani
    Matteo Ippoliti
    Andrew Dunsworth
    Bill Huggins
    Markus Hoffmann
    Alexis Morvan
    Josh Cogan
    Ben Curtin
    Guifre Vidal
    Bob Buckley
    Tom O'Brien
    John Mark Kreikebaum
    Rajeev Acharya
    Joonho Lee
    Ningfeng Zhu
    Shirin Montazeri
    Sergei Isakov
    Jamie Yao
    Clarke Smith
    Rebecca Potter
    Jeremy Hilton
    Paula Heu
    Alexei Kitaev
    Alex Crook
    Fedor Kostritsa
    Kim Ming Lau
    Dmitry Abanin
    Trent Huang
    Aaron Shorter
    Steve Habegger
    Gina Bortoli
    Seun Omonije
    Charles Rocque
    Vladimir Shvarts
    Alfredo Torres
    Anthony Megrant
    Charles Neill
    Michael Hamilton
    Dar Gilboa
    Lily Laws
    Nicholas Bushnell
    Ramis Movassagh
    Mike Shearn
    Wojtek Mruczkiewicz
    Desmond Chik
    Leonid Pryadko
    Xiao Mi
    Brooks Foxen
    Frank Arute
    Alejo Grajales Dau
    Yaxing Zhang
    Alexander Lill
    JiunHow Ng
    Justin Iveland
    Marco Szalay
    Orion Martin
    Juhwan Yoo
    Michael Newman
    William Giang
    Alex Opremcak
    Amanda Mieszala
    William Courtney
    Andrey Klots
    Wayne Liu
    Pavel Laptev
    Paul Conner
    Rolando Somma
    Vadim Smelyanskiy
    Jesse Hoke
    Benjamin Chiaro
    Grayson Young
    Tim Burger
    ILYA Drozdov
    Agustin Di Paolo
    Jimmy Chen
    Marika Kieferova
    Michael Broughton
    Negar Saei
    Juan Atalaya
    Markus Ansmann
    Pavol Juhas
    Murray Ich Nguyen
    Yuri Lensky
    Daniel Eppens
    Roberto Collins
    Jindra Skruzny
    Yu Chen
    Reza Fatemi
    Leon Brill
    Ashley Huff
    Doug Strain
    Monica Hansen
    Noah Shutty
    Ebrahim Forati
    Dave Landhuis
    Kenny Lee
    Ping Yeh
    Kunal Arya
    Henry Schurkus
    Cheng Xing
    Cody Jones
    Edward Farhi
    Raja Gosula
    Andre Petukhov
    Alexander Korotkov
    Ani Nersisyan
    Christopher Schuster
    George Sterling
    Kostyantyn Kechedzhi
    Trond Andersen
    Alexandre Bourassa
    Kannan Sankaragomathi
    Vinicius Ferreira
    Nature, 622 (2023), 481–486
    Preview abstract Measurement has a special role in quantum theory: by collapsing the wavefunction, it can enable phenomena such as teleportation and thereby alter the ‘arrow of time’ that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space–time that go beyond the established paradigms for characterizing phases, either in or out of equilibrium. For present-day noisy intermediate-scale quantum (NISQ) processors, the experimental realization of such physics can be problematic because of hardware limitations and the stochastic nature of quantum measurement. Here we address these experimental challenges and study measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping to avoid mid-circuit measurement and access different manifestations of the underlying phases, from entanglement scaling to measurement-induced teleportation. We obtain finite-sized signatures of a phase transition with a decoding protocol that correlates the experimental measurement with classical simulation data. The phases display remarkably different sensitivity to noise, and we use this disparity to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realizing measurement-induced physics at scales that are at the limits of current NISQ processors. View details
    Preview abstract Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction [1, 2] offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low in order for logical performance to improve with increasing code size. Here, we report the measurement of logical qubit performance scaling across multiple code sizes, and demonstrate that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number. We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle (2.914%±0.016% compared to 3.028%±0.023%). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a 1.7 × 10−6 logical error per round floor set by a single high-energy event (1.6 × 10−7 when excluding this event). We are able to accurately model our experiment, and from this model we can extract error budgets that highlight the biggest challenges for future systems. These results mark the first experimental demonstration where quantum error correction begins to improve performance with increasing qubit number, and illuminate the path to reaching the logical error rates required for computation. View details
    Noise-resilient Majorana Edge Modes on a Chain of Superconducting Qubits
    Zijun Chen
    Brooks Foxen
    Masoud Mohseni
    Emily Mount
    Joao Basso
    Andrew Dunsworth
    William J. Huggins
    Yuan Su
    Markus Rudolf Hoffmann
    Alexis Morvan
    Guifre Vidal
    Bob Benjamin Buckley
    Thomas E O'Brien
    John Mark Kreikebaum
    Rajeev Acharya
    Joonho Lee
    Shirin Montazeri
    Sergei Isakov
    Jamie Yao
    Rebecca Potter
    Jeremy Patterson Hilton
    Alexei Kitaev
    Alex Crook
    Fedor Kostritsa
    Kim Ming Lau
    Dmitry Abanin
    Trent Huang
    Steve Habegger
    Alexa Rubinov
    Vladimir Shvarts
    Anthony Megrant
    Charles Neill
    Dar Gilboa
    Nicholas Bushnell
    Mike Shearn
    Wojtek Mruczkiewicz
    Xiao Mi
    Frank Carlton Arute
    Alejandro Grajales Dau
    Yaxing Zhang
    Lara Faoro
    Justin Thomas Iveland
    Marco Szalay
    Orion Martin
    Juhwan Yoo
    Michael Newman
    William Giang
    Alex Opremcak
    William Courtney
    Andrey Klots
    Wayne Liu
    Pavel Laptev
    Paul Conner
    Vadim Smelyanskiy
    Benjamin Chiaro
    Bernardo Meurer Costa
    Michael Blythe Broughton
    Juan Atalaya
    Daniel Eppens
    Roberto Collins
    Igor Aleiner
    Yu Chen
    Reza Fatemi
    Leon Brill
    Ashley Anne Huff
    Doug Strain
    Ebrahim Forati
    Dave Landhuis
    Kenny Lee
    Ping Yeh
    Kunal Arya
    Michel Henri Devoret
    Cody Jones
    Edward Farhi
    Andre Gregory Petukhov
    Alexander Korotkov
    Christopher Schuster
    Kostyantyn Kechedzhi
    Trond Ikdahl Andersen
    Alexandre Bourassa
    Kannan Aryaperumal Sankaragomathi
    Science (2022) (to appear)
    Preview abstract Inherent symmetry of a quantum system may protect its otherwise fragile states. Leveraging such protection requires testing its robustness against uncontrolled environmental interactions. Using 47 superconducting qubits, we implement the kicked Ising model which exhibits Majorana edge modes (MEMs) protected by a $\mathbb{Z}_2$-symmetry. Remarkably, we find that any multi-qubit Pauli operator overlapping with the MEMs exhibits a uniform decay rate comparable to single-qubit relaxation rates, irrespective of its size or composition. This finding allows us to accurately reconstruct the exponentially localized spatial profiles of the MEMs. Spectroscopic measurements further indicate exponentially suppressed hybridization between the MEMs over larger system sizes, which manifests as a strong resilience against low-frequency noise. Our work elucidates the noise sensitivity of symmetry-protected edge modes in a solid-state environment. View details
    Quantum Approximate Optimization of Non-Planar Graph Problems on a Planar Superconducting Processor
    Michael Streif
    Florian Neukart
    Andrea Skolik
    Martin Leib
    Ben Chiaro
    Bryan O'Gorman
    A.G. Petukhov
    Masoud Mohseni
    Andrew Dunsworth
    Rami Barends
    Amit Vainsencher
    John Martinis
    Josh Mutus
    Bob Benjamin Buckley
    Thomas E O'Brien
    Sergei Isakov
    Jamie Yao
    Fedor Kostritsa
    Steve Habegger
    Anthony Megrant
    Charles Neill
    Nicholas Bushnell
    Harry Putterman
    Wojtek Mruczkiewicz
    Xiao Mi
    Leo Zhou
    Brooks Riley Foxen
    Frank Carlton Arute
    Marco Szalay
    Orion Martin
    William Courtney
    Pavel Laptev
    Vadim Smelyanskiy
    Jimmy Chen
    Mike Lindmark
    Michael Blythe Broughton
    Juan Atalaya
    Roberto Collins
    Yu Chen
    Kevin Jeffery Sung
    Doug Strain
    Rob Graff
    Dave Landhuis
    Kunal Arya
    Cody Jones
    Edward Farhi
    Alexander Korotkov
    Kostyantyn Kechedzhi
    Nature Physics (2021)
    Preview abstract Faster algorithms for combinatorial optimization could prove transformative for diverse areas such as logistics, finance and machine learning. Accordingly, the possibility of quantum enhanced optimization has driven much interest in quantum technologies. Here we demonstrate the application of the Google Sycamore superconducting qubit quantum processor to combinatorial optimization problems with the quantum approximate optimization algorithm (QAOA). Like past QAOA experiments, we study performance for problems defined on the planar connectivity graph native to our hardware; however, we also apply the QAOA to the Sherrington–Kirkpatrick model and MaxCut, non-native problems that require extensive compilation to implement. For hardware-native problems, which are classically efficient to solve on average, we obtain an approximation ratio that is independent of problem size and observe that performance increases with circuit depth. For problems requiring compilation, performance decreases with problem size. Circuits involving several thousand gates still present an advantage over random guessing but not over some efficient classical algorithms. Our results suggest that it will be challenging to scale near-term implementations of the QAOA for problems on non-native graphs. As these graphs are closer to real-world instances, we suggest more emphasis should be placed on such problems when using the QAOA to benchmark quantum processors. View details
    Demonstrating a Continuous Set of Two-qubit Gates for Near-term Quantum Algorithms
    Ben Chiaro
    Edward Farhi
    Masoud Mohseni
    Andrew Dunsworth
    Rami Barends
    Amit Vainsencher
    John Martinis
    Josh Mutus
    Sergei Isakov
    Jamie Yao
    Fedor Kostritsa
    Trent Huang
    Anthony Megrant
    Charles Neill
    Xiao Mi
    Brooks Riley Foxen
    Frank Carlton Arute
    Vadim Smelyanskiy
    Jimmy Chen
    Roberto Collins
    Yu Chen
    Rob Graff
    Dave Landhuis
    Kunal Arya
    Alexander Korotkov
    Kostyantyn Kechedzhi
    arXiv:2001.08343 (2020)
    Preview abstract Quantum algorithms offer a dramatic speedup for computational problems in machine learning, material science, and chemistry. However, any near-term realizations of these algorithms will need to be heavily optimized to fit within the finite resources offered by existing noisy quantum hardware. Here, taking advantage of the strong adjustable coupling of gmon qubits, we demonstrate a continuous two qubit gate set that can provide a 5x reduction in circuit depth. We implement two gate families: an iSWAP-like gate to attain an arbitrary swap angle, $\theta$, and a CPHASE gate that generates an arbitrary conditional phase, $\phi$. Using one of each of these gates, we can perform an arbitrary two qubit gate within the excitation-preserving subspace allowing for a complete implementation of the so-called Fermionic Simulation, or fSim, gate set. We benchmark the fidelity of the iSWAP-like and CPHASE gate families as well as 525 other fSim gates spread evenly across the entire fSim($\theta$, $\phi$) parameter space achieving purity-limited average two qubit Pauli error of $3.8 \times 10^{-3}$ per fSim gate. View details
    Hartree-Fock on a Superconducting Qubit Quantum Computer
    Nathan Wiebe
    Tyler Y. Takeshita
    Masoud Mohseni
    Andrew Dunsworth
    Alan Ho
    William J. Huggins
    Eric Ostby
    Rami Barends
    Amit Vainsencher
    John Martinis
    Josh Mutus
    Bob Benjamin Buckley
    Thomas E O'Brien
    Sergei Isakov
    Jamie Yao
    Fedor Kostritsa
    Trent Huang
    Steve Habegger
    Anthony Megrant
    Charles Neill
    Nicholas Bushnell
    Harry Putterman
    Wojtek Mruczkiewicz
    Xiao Mi
    Brooks Riley Foxen
    Frank Carlton Arute
    Marco Szalay
    Orion Martin
    William Courtney
    Pavel Laptev
    Vadim Smelyanskiy
    Benjamin Chiaro
    Jimmy Chen
    Mike Lindmark
    Michael Blythe Broughton
    Roberto Collins
    Yu Chen
    Kevin Jeffery Sung
    Doug Strain
    Rob Graff
    Dave Landhuis
    Ping Yeh
    Kunal Arya
    Cody Jones
    Edward Farhi
    Andre Gregory Petukhov
    Alexander Korotkov
    Kostyantyn Kechedzhi
    Science, 369 (2020), pp. 6507
    Preview abstract As the search continues for useful applications of noisy intermediate scale quantum devices, variational simulations of fermionic systems remain one of the most promising directions. Here, we perform a series of quantum simulations of chemistry which involve twice the number of qubits and more than ten times the number of gates as the largest prior experiments. We model the binding energy of ${\rm H}_6$, ${\rm H}_8$, ${\rm H}_{10}$ and ${\rm H}_{12}$ chains as well as the isomerization of diazene. We also demonstrate error-mitigation strategies based on $N$-representability which dramatically improve the effective fidelity of our experiments. Our parameterized ansatz circuits realize the Givens rotation approach to free fermion evolution, which we variationally optimize to prepare the Hartree-Fock wavefunction. This ubiquitous algorithmic primitive corresponds to a rotation of the orbital basis and is required by many proposals for correlated simulations of molecules and Hubbard models. Because free fermion evolutions are classically tractable to simulate, yet still generate highly entangled states over the computational basis, we use these experiments to benchmark the performance of our hardware while establishing a foundation for scaling up more complex correlated quantum simulations of chemistry. View details
    TensorFlow Quantum: A Software Framework for Quantum Machine Learning
    Martin Leib
    Owen Lockwood
    Sofiene Jerbi
    Alexander Zlokapa
    Roeland Wiersema
    Hongxiang Chen
    Trevor McCourt
    David Von Dollen
    Chuxiang Cao
    Vedran Djunko
    Hsin-Yuan Huang
    Evan Peters
    Michael Streif
    Andrea Skolik
    Antonio J. Martinez
    Masoud Mohseni
    Alan K. Ho
    Guillaume Verdon
    Sergei V. Isakov
    Michael Broughton
    Philip Massey
    Ramin Halavati
    (2020)
    Preview abstract We introduce TensorFlow Quantum (TFQ), an open source library for the rapid prototyping of hybrid quantum-classical models for classical or quantum data. This framework offers high-level abstractions for the design and training of both discriminative and generative quantum models under TensorFlow and supports high-performance quantum circuit simulators. We provide an overview of the software architecture and building blocks through several examples and review the theory of hybrid quantum-classical neural networks. We illustrate TFQ functionalities via several basic applications including supervised learning for quantum classification, quantum control, simulating noisy quantum circuits, and quantum approximate optimization. Moreover, we demonstrate how one can apply TFQ to tackle advanced quantum learning tasks including meta-learning, layerwise learning, Hamiltonian learning, sampling thermal states, variational quantum eigensolvers, classification of quantum phase transitions, generative adversarial networks, and reinforcement learning. We hope this framework provides the necessary tools for the quantum computing and machine learning research communities to explore models of both natural and artificial quantum systems, and ultimately discover new quantum algorithms which could potentially yield a quantum advantage. View details