2007/02/28 by Jens Koch, Terri M. Yu, Jay Gambetta +12 · 1 voice · 181 citations
Computer Science · Physics and Astronomy · #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #cond-mat.mes-hall #quant-ph
paper · pdf · doi:10.1103/physreva.76.042319
published as Phys. Rev. A 76, 042319 (2007) · 21 pages, 12 figures; title changed, small changes in the text, additional figure
arxiv published 2007/02/28 · arxiv created 2007/09/26 · arxiv updated 2007/09/26 · openalex publication_date 2007/10/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Short dephasing times pose one of the main challenges in realizing a quantum computer. Different approaches have been devised to cure this problem for superconducting qubits, a prime example being the operation of such devices at optimal working points, so-called "sweet spots." This latter approach led to significant improvement of T2 times in Cooper pair box qubits [D. Vion et al., Science 296, 886 (2002)]. Here, we introduce a new type of superconducting qubit called the "transmon." Unlike the charge qubit, the transmon is designed to operate in a regime of significantly increased ratio of Josephson energy and charging energy EJ/EC. The transmon benefits from the fact that its charge dispersion decreases exponentially with EJ/EC, while its loss in anharmonicity is described by a weak power law. As a result, we predict a drastic reduction in sensitivity to charge noise relative to the Cooper pair box and an increase in the qubit-photon coupling, while maintaining sufficient anharmonicity for selective qubit control. Our detailed analysis of the full system shows that this gain is not compromised by increased noise in other known channels.