Suppressing quantum errors by scaling a surface code logical qubit
Creators: name: Acharya, Rajeev
name: Aleiner, Igor
name: Allen, Richard
name: Andersen, Trond I.
name: Ansmann, Markus
name: Arute, Frank
name: Arya, Kunal
name: Asfaw, Abraham
name: Atalaya, Juan
name: Babbush, Ryan
name: Bacon, Dave
name: Bardin, Joseph C.
name: Basso, Joao
name: Bengtsson, Andreas
name: Boixo, Sergio
name: Bortoli, Gina
name: Bourassa, Alexandre
name: Bovaird, Jenna
name: Brill, Leon
name: Broughton, Michael
name: Buckley, Bob B.
name: Buell, David A.
name: Burger, Tim
name: Burkett, Brian
name: Bushnell, Nicholas
name: Chen, Yu
name: Chen, Zijun
name: Chiaro, Ben
name: Cogan, Josh
name: Collins, Roberto
name: Conner, Paul
name: Courtney, William
name: Crook, Alexander L.
name: Curtin, Ben
name: Debroy, Dripto M.
name: Barba, Alexander Del Toro
name: Demura, Sean
name: Dunsworth, Andrew
name: Eppens, Daniel
name: Erickson, Catherine
name: Faoro, Lara
name: Farhi, Edward
name: Fatemi, Reza
name: Burgos, Leslie Flores
name: Forati, Ebrahim
name: Fowler, Austin G.
name: Foxen, Brooks
name: Giang, William
name: Gidney, Craig
name: Gilboa, Dar
name: Giustina, Marissa
name: Dau, Alejandro Grajales
name: Gross, Jonathan A.
name: Habegger, Steve
name: Hamilton, Michael C.
name: Harrigan, Matthew P.
name: Harrington, Sean D.
name: Higgott, Oscar
name: Hilton, Jeremy
name: Hoffmann, Markus
name: Hong, Sabrina
name: Huang, Trent
name: Huff, Ashley
name: Huggins, William J.
name: Ioffe, Lev B.
name: Isakov, Sergei V.
name: Iveland, Justin
name: Jeffrey, Evan
name: Jiang, Zhang
name: Jones, Cody
name: Juhas, Pavol
name: Kafri, Dvir
name: Kechedzhi, Kostyantyn
name: Kelly, Julian
name: Khattar, Tanuj
name: Khezri, Mostafa
name: Kieferová, Mária
name: Kim, Seon
name: Kitaev, Alexei
name: Klimov, Paul V.
name: Klots, Andrey R.
name: Korotkov, Alexander N.
name: Kostritsa, Fedor
name: Kreikebaum, John Mark
name: Landhuis, David
name: Laptev, Pavel
name: Lau, Kim-Ming
name: Laws, Lily
name: Lee, Joonho
name: Lee, Kenny
name: Lester, Brian J.
name: Lill, Alexander
name: Liu, Wayne
name: Locharla, Aditya
name: Lucero, Erik
name: Malone, Fionn D.
name: Marshall, Jeffrey
name: Martin, Orion
name: McClean, Jarrod R.
name: Mccourt, Trevor
name: McEwen, Matt
name: Megrant, Anthony
name: Costa, Bernardo Meurer
name: Mi, Xiao
name: Miao, Kevin C.
name: Mohseni, Masoud
name: Montazeri, Shirin
name: Morvan, Alexis
name: Mount, Emily
name: Mruczkiewicz, Wojciech
name: Naaman, Ofer
name: Neeley, Matthew
name: Neill, Charles
name: Nersisyan, Ani
name: Neven, Hartmut
name: Newman, Michael
name: Ng, Jiun How
name: Nguyen, Anthony
name: Nguyen, Murray
name: Niu, Murphy Yuezhen
name: O'Brien, Thomas E.
name: Opremcak, Alex
name: Platt, John
name: Petukhov, Andre
name: Potter, Rebecca
name: Pryadko, Leonid P.
name: Quintana, Chris
name: Roushan, Pedram
name: Rubin, Nicholas C.
name: Saei, Negar
name: Sank, Daniel
name: Sankaragomathi, Kannan
name: Satzinger, Kevin J.
name: Schurkus, Henry F.
name: Schuster, Christopher
name: Shearn, Michael J.
name: Shorter, Aaron
name: Shvarts, Vladimir
name: Skruzny, Jindra
name: Smelyanskiy, Vadim
name: Smith, W. Clarke
name: Sterling, George
name: Strain, Doug
name: Szalay, Marco
name: Torres, Alfredo
name: Vidal, Guifre
name: Villalonga, Benjamin
name: Heidweiller, Catherine Vollgraff
name: White, Theodore
name: Xing, Cheng
name: Yao, Z. Jamie
name: Yeh, Ping
name: Yoo, Juhwan
name: Young, Grayson
name: Zalcman, Adam
name: Zhang, Yaxing
name: Zhu, Ningfeng
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction 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 ($2.914\%\pm 0.016\%$ compared to $3.028\%\pm 0.023\%$). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a $1.7\times10^{-6}$ logical error per round floor set by a single high-energy event ($1.6\times10^{-7}$ 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, illuminating the path to reaching the logical error rates required for computation.
description: Main text: 6 pages, 4 figures. v2: Update author list, references, Fig. S12, Table IV