Hartree-Fock on a superconducting qubit quantum computer
Creators: name: Arute, Frank
name: Arya, Kunal
name: Babbush, Ryan
name: Bacon, Dave
name: Bardin, Joseph C.
name: Barends, Rami
name: Boixo, Sergio
name: Broughton, Michael
name: Buckley, Bob B.
name: Buell, David A.
name: Burkett, Brian
name: Bushnell, Nicholas
name: Chen, Yu
name: Chen, Zijun
name: Chiaro, Benjamin
name: Collins, Roberto
name: Courtney, William
name: Demura, Sean
name: Dunsworth, Andrew
name: Eppens, Daniel
name: Farhi, Edward
name: Fowler, Austin
name: Foxen, Brooks
name: Gidney, Craig
name: Giustina, Marissa
name: Graff, Rob
name: Habegger, Steve
name: Harrigan, Matthew P.
name: Ho, Alan
name: Hong, Sabrina
name: Huang, Trent
name: Huggins, William J.
name: Ioffe, Lev
name: Isakov, Sergei V.
name: Jeffrey, Evan
name: Jiang, Zhang
name: Jones, Cody
name: Kafri, Dvir
name: Kechedzhi, Kostyantyn
name: Kelly, Julian
name: Kim, Seon
name: Klimov, Paul V.
name: Korotkov, Alexander
name: Kostritsa, Fedor
name: Landhuis, David
name: Laptev, Pavel
name: Lindmark, Mike
name: Lucero, Erik
name: Martin, Orion
name: Martinis, John M.
name: McClean, Jarrod R.
name: McEwen, Matt
name: Megrant, Anthony
name: Mi, Xiao
name: Mohseni, Masoud
name: Mruczkiewicz, Wojciech
name: Mutus, Josh
name: Naaman, Ofer
name: Neeley, Matthew
name: Neill, Charles
name: Neven, Hartmut
name: Niu, Murphy Yuezhen
name: O'Brien, Thomas E.
name: Ostby, Eric
name: Petukhov, Andre
name: Putterman, Harald
name: Quintana, Chris
name: Roushan, Pedram
name: Rubin, Nicholas C.
name: Sank, Daniel
name: Satzinger, Kevin J.
name: Smelyanskiy, Vadim
name: Strain, Doug
name: Sung, Kevin J.
name: Szalay, Marco
name: Takeshita, Tyler Y.
name: Vainsencher, Amit
name: White, Theodore
name: Wiebe, Nathan
name: Yao, Z. Jamie
name: Yeh, Ping
name: Zalcman, Adam
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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 the largest of which involved a dozen qubits, 78 two-qubit gates, and 114 one-qubit gates. 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 non-interacting 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 non-interacting 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.
description: updated link to experiment code, new version containing expanded data sets and corrected figure label