Demonstrating a Long-Coherence Dual-Rail Erasure Qubit Using Tunable Transmons
Harry Levine, Arbel Haim, Jimmy S. C. Hung, Nasser Alidoust, Mahmoud Kalaee, Laura DeLorenzo, E. Alex Wollack, Patricio Arrangoiz-Arriola, Amirhossein Khalajhedayati, Rohan Sanil, Hesam Moradinejad, Yotam Vaknin, Aleksander Kubica, David Hover, Shahriar Aghaeimeibodi, Joshua Ari Alcid, Chungheon Baek, J. Barnett, K. Bawdekar, Przemysław Bienias, H. A. Carson, Chen Chen, L. Chen, Harutiun Chinkezian, E M Chisholm, Alexander M. Clifford, R. Cosmic, N. Crisosto, A. M. Dalzell, Edward D. Davis, John D'Ewart, Stefan Diez, Noel D’Souza, Philipp T. Dumitrescu, E. S. Elkhouly, Ming Fang, Yawen Fang, Steven T. Flammia, Matthew J. Fling, Gonzalo Cerruela García, M. K. Gharzai, Alexey V. Gorshkov, Mason Gray, Sebastian Grimberg, Arne L. Grimsmo, Connor T. Hann, Yu He, Steven Heidel, Steve B. Howell, Matthew A. Hunt, Jana M. Iverson, Ignace Jarrige, Liang Jiang, William M. Jones, R. B. Karabalin, Peter J. Karalekas, Andrew J. Keller, D. Lasi, Menyoung Lee, Victoria Ly, Gregory S. MacCabe, Neha Mahuli, Guillaume Marcaud, Matthew H. Matheny, Sam McArdle, Gavin McCabe, G. Merton, Chris Miles, Ashley Milsted, Anurag Mishra, Lorenzo Moncelsi, Mahdi Naghiloo, Kyungjoo Noh, Eric Oblepias, Gerson Ortuno, John Clai Owens, Jason Pagdilao, Marco A. Panduro, Jean-Philip Paquette, Ram N. Patel, G. A. Peairs, David Perello, Eric Peterson, Salvatore Ponte, Harald Putterman, Gil Refael, Philip Reinhold, Robert Resnick, Omar A. Reyna, Randolph de la Rosa Rodríguez, J. Rose, A. H. Rubin, M. C. Runyan, Colm A. Ryan, Abdulrahman Sahmoud, Thomas Scaffidi, Babar Shah, Salome Siavoshi, Prasahnt Sivarajah, Trenton Skogland
Abstract
Quantum error correction with erasure qubits promises significant advantages over standard error correction due to favorable thresholds for erasure errors. To realize this advantage in practice requires a qubit for which nearly all errors are such erasure errors, and the ability to check for erasure errors without dephasing the qubit. We demonstrate that a “dual-rail qubit” consisting of a pair of resonantly coupled transmons can form a highly coherent erasure qubit, where transmon <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>T</a:mi><a:mn>1</a:mn></a:msub></a:math> errors are converted into erasure errors and residual dephasing is strongly suppressed, leading to millisecond-scale coherence within the qubit subspace. We show that single-qubit gates are limited primarily by erasure errors, with erasure probability <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msub><c:mi>p</c:mi><c:mtext>erasure</c:mtext></c:msub><c:mo>=</c:mo><c:mn>2.19</c:mn><c:mo stretchy="false">(</c:mo><c:mn>2</c:mn><c:mo stretchy="false">)</c:mo><c:mo>×</c:mo><c:msup><c:mn>10</c:mn><c:mrow><c:mo>−</c:mo><c:mn>3</c:mn></c:mrow></c:msup></c:math> per gate while the residual errors are <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mo>∼</g:mo><g:mn>40</g:mn></g:math> times lower. We further demonstrate midcircuit detection of erasure errors while introducing <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mo><</i:mo><i:mn>0.1</i:mn><i:mo>%</i:mo></i:math> dephasing error per check. Finally, we show that the suppression of transmon noise allows this dual-rail qubit to preserve high coherence over a broad tunable operating range, offering an improved capacity to avoid frequency collisions. This work establishes transmon-based dual-rail qubits as an attractive building block for hardware-efficient quantum error correction. Published by the American Physical Society 2024