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arXiv · 2211.04728

Overcoming leakage in scalable quantum error correction

Kevin C. Miao·Matt McEwen·Juan Atalaya·Dvir Kafri·Leonid P. Pryadko·Andreas Bengtsson·Alex Opremcak·Kevin J. Satzinger·Zijun Chen·Paul V. Klimov·Chris Quintana·Rajeev Acharya·Kyle Anderson·Markus Ansmann·Frank Arute·Kunal Arya·Abraham Asfaw·Joseph C. Bardin·Alexandre Bourassa·Jenna Bovaird·Leon Brill·Bob B. Buckley·David A. Buell·Tim Burger·Brian Burkett·Nicholas Bushnell·Juan Campero·Ben Chiaro·Roberto Collins·Paul Conner·Alexander L. Crook·Ben Curtin·Dripto M. Debroy·Sean Demura·Andrew Dunsworth·Catherine Erickson·Reza Fatemi·Vinicius S. Ferreira·Leslie Flores Burgos·Ebrahim Forati·Austin G. Fowler·Brooks Foxen·Gonzalo Garcia·William Giang·Craig Gidney·Marissa Giustina·Raja Gosula·Alejandro Grajales Dau·Jonathan A. Gross·Michael C. Hamilton·Sean D. Harrington·Paula Heu·Jeremy Hilton·Markus R. Hoffmann·Sabrina Hong·Trent Huang·Ashley Huff·Justin Iveland·Evan Jeffrey·Zhang Jiang·Cody Jones·Julian Kelly·Seon Kim·Fedor Kostritsa·John Mark Kreikebaum·David Landhuis·Pavel Laptev·Lily Laws·Kenny Lee·Brian J. Lester·Alexander T. Lill·Wayne Liu·Aditya Locharla·Erik Lucero·Steven Martin·Anthony Megrant·Xiao Mi·Shirin Montazeri·Alexis Morvan·Ofer Naaman·Matthew Neeley·Charles Neill·Ani Nersisyan·Michael Newman·Jiun How Ng·Anthony Nguyen·Murray Nguyen·Rebecca Potter·Charles Rocque·Pedram Roushan·Kannan Sankaragomathi·Christopher Schuster·Michael J. Shearn·Aaron Shorter·Noah Shutty·Vladimir Shvarts·Jindra Skruzny·W. Clarke Smith·George Sterling·Marco Szalay
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Abstract

Leakage of quantum information out of computational states into higher energy states represents a major challenge in the pursuit of quantum error correction (QEC). In a QEC circuit, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade the exponential suppression of logical error with scale, challenging the feasibility of QEC as a path towards fault-tolerant quantum computation. Here, we demonstrate the execution of a distance-3 surface code and distance-21 bit-flip code on a Sycamore quantum processor where leakage is removed from all qubits in each cycle. This shortens the lifetime of leakage and curtails its ability to spread and induce correlated errors. We report a ten-fold reduction in steady-state leakage population on the data qubits encoding the logical state and an average leakage population of less than $1 \times 10^{-3}$ throughout the entire device. The leakage removal process itself efficiently returns leakage population back to the computational basis, and adding it to a code circuit prevents leakage from inducing correlated error across cycles, restoring a fundamental assumption of QEC. With this demonstration that leakage can be contained, we resolve a key challenge for practical QEC at scale.

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Kevin C. Miao, Matt McEwen, Juan Atalaya, Dvir Kafri, Leonid P. Pryadko, Andreas Bengtsson, Alex Opremcak, Kevin J. Satzinger, Zijun Chen, Paul V. Klimov, Chris Quintana, Rajeev Acharya, Kyle Anderson, Markus Ansmann, Frank Arute, Kunal Arya, Abraham Asfaw, Joseph C. Bardin, Alexandre Bourassa, Jenna Bovaird, Leon Brill, Bob B. Buckley, David A. Buell, Tim Burger, Brian Burkett, Nicholas Bushnell, Juan Campero, Ben Chiaro, Roberto Collins, Paul Conner, Alexander L. Crook, Ben Curtin, Dripto M. Debroy, Sean Demura, Andrew Dunsworth, Catherine Erickson, Reza Fatemi, Vinicius S. Ferreira, Leslie Flores Burgos, Ebrahim Forati, Austin G. Fowler, Brooks Foxen, Gonzalo Garcia, William Giang, Craig Gidney, Marissa Giustina, Raja Gosula, Alejandro Grajales Dau, Jonathan A. Gross, Michael C. Hamilton, Sean D. Harrington, Paula Heu, Jeremy Hilton, Markus R. Hoffmann, Sabrina Hong, Trent Huang, Ashley Huff, Justin Iveland, Evan Jeffrey, Zhang Jiang, Cody Jones, Julian Kelly, Seon Kim, Fedor Kostritsa, John Mark Kreikebaum, David Landhuis, Pavel Laptev, Lily Laws, Kenny Lee, Brian J. Lester, Alexander T. Lill, Wayne Liu, Aditya Locharla, Erik Lucero, Steven Martin, Anthony Megrant, Xiao Mi, Shirin Montazeri, Alexis Morvan, Ofer Naaman, Matthew Neeley, Charles Neill, Ani Nersisyan, Michael Newman, Jiun How Ng, Anthony Nguyen, Murray Nguyen, Rebecca Potter, Charles Rocque, Pedram Roushan, Kannan Sankaragomathi, Christopher Schuster, Michael J. Shearn, Aaron Shorter, Noah Shutty, Vladimir Shvarts, Jindra Skruzny, W. Clarke Smith, George Sterling, Marco Szalay. 2022-11-09. Overcoming leakage in scalable quantum error correction. https://doi.org/10.1038/s41567-023-02226-w

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