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Increasing connectivity and decreasing qubit-state delocalization without compromising the speed and accuracy of elementary gate operations are topical challenges in the development of large-scale superconducting quantum computers. In this…

Quantum Physics · Physics 2026-03-12 Tuure Orell , Hao Hsu , Joona Andersson , Jani Tuorila , Frank Deppe , Hsiang-Sheng Ku

Entangling gates are an essential component of quantum computers. However, generating high-fidelity gates, in a scalable manner, remains a major challenge in all quantum information processing platforms. Accordingly, improving the fidelity…

Quantum Physics · Physics 2023-02-01 Yotam Shapira , Sapir Cohen , Nitzan Akerman , Ady Stern , Roee Ozeri

Eliminating residual ZZ interactions in a two-qubit system is essential for reducing coherent errors during quantum operations. In a superconducting circuit platform, coupling two transmon qubits via a transmon coupler has been shown to…

Gate-based universal quantum computation is formulated in terms of two types of operations: local single-qubit gates, which are typically easily implementable, and two-qubit entangling gates, whose faithful implementation remains one of the…

Quantum Physics · Physics 2023-10-18 Xiaoqin Gao , Paul Appel , Nicolai Friis , Martin Ringbauer , Marcus Huber

Noise in entangled quantum systems is difficult to characterize due to many-body effects involving multiple degrees of freedom. This noise poses a challenge to quantum computing, where two-qubit gate performance is critical. Here, we…

Superconducting quantum circuits derive their nonlinearity from the Josephson energy-phase relation. Besides the fundamental $\cos\phi$ term, this relation can also contain higher Fourier harmonics $\cos(k\phi)$ corresponding to correlated…

We study a Cooper-pair transistor realized by two Josephson weak links that enclose a superconducting island in an InSb-Al hybrid nanowire. When the nanowire is subject to a magnetic field, isolated subgap levels arise in the…

We describe a scheme that enables a strong Jaynes-Cummings coupling between a topological qubit and a superconducting flux qubit. The coupling strength is dependent on the phase difference between two superconductors on a topological…

Quantum Physics · Physics 2013-01-22 Fang-Yu Hong , Jing-Li Fu , Zhi-Yan Zhu

A recently developed theory for eliminating decoherence and design constraints in quantum computers, ``encoded recoupling and decoupling'', is shown to be fully compatible with a promising proposal for an architecture enabling scalable…

Quantum Physics · Physics 2016-09-08 D. A. Lidar , L. -A Wu

Superconducting qubits offer an unprecedentedly high degree of flexibility in terms of circuit encoding and parameter choices. However, in designing the qubit parameters one typically faces the conflicting goals of long coherence times and…

Quantum Physics · Physics 2025-04-08 C. A. Siegele , A. A. Sokolova , L. N. Kapoor , F. Hassani , J. M. Fink

Hybrid semiconductor-superconductor qubits have recently emerged as a promising alternative to traditional platforms, combining material advantages with device-level tunability. A defining feature is their gate-tunable Josephson coupling,…

Protected superconducting qubits such as the $0$-$\pi$ qubit promise to substantially reduce physical error rates. However, a key challenge in the field is designing gates for these qubits that do not compromise their protection, or become…

Quantum Physics · Physics 2026-01-16 Xanda C Kolesnikow , Thomas B Smith , Felix Thomsen , Abhijeet Alase , Andrew C Doherty

We show that a large number of ions stored in a Penning trap, and forming a 2D Coulomb crystal, provides an almost ideal system for scalable quantum computation and quantum simulation. In particular, the coupling of the internal states to…

Quantum Physics · Physics 2009-11-13 D. Porras , J. I. Cirac

Gate-tunable transmons (gatemons) employing semiconductor Josephson junctions have recently emerged as building blocks for hybrid quantum circuits. In this study, we present a gatemon fabricated in planar Germanium. We induce…

The efficient implementation of many-body interactions in superconducting circuits allows for the realization of multipartite entanglement and topological codes, as well as the efficient simulation of highly correlated fermionic systems. We…

Quantum Physics · Physics 2015-06-19 A. Mezzacapo , L. Lamata , S. Filipp , E. Solano

The three-electron configuration of gate-defined double quantum dots encodes a promising qubit for quantum information processing. I propose a two-qubit entangling gate using a pulse-gated manipulation procedure. The requirements for…

Mesoscale and Nanoscale Physics · Physics 2015-01-23 Sebastian Mehl

A challenge in building large-scale superconducting quantum processors is to find the right balance between coherence, qubit addressability, qubit-qubit coupling strength, circuit complexity and the number of required control lines. Leading…

Quantum Physics · Physics 2020-10-27 S. Krinner , P. Kurpiers , B. Royer , P. Magnard , I. Tsitsilin , J. -C. Besse , A. Remm , A. Blais , A. Wallraff

Precision control over hybrid physical systems at the quantum level is important for the realization of many quantum-based technologies. In the field of quantum information processing (QIP) and quantum networking, various proposals discuss…

Quantum Physics · Physics 2016-01-20 T. R. Tan , J. P. Gaebler , Y. Lin , Y. Wan , R. Bowler , D. Leibfried , D. J. Wineland

Encoding quantum information in quantum states with disjoint wave-function support and noise insensitive energies is the key behind the idea of qubit protection. While fully protected qubits are expected to offer exponential protection…

Improving two-qubit gate performance and suppressing crosstalk are major, but often competing, challenges to achieving scalable quantum computation. In particular, increasing the coupling to realize faster gates has been intrinsically…

Quantum Physics · Physics 2021-09-29 A. Kandala , K. X. Wei , S. Srinivasan , E. Magesan , S. Carnevale , G. A. Keefe , D. Klaus , O. Dial , D. C. McKay