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We propose a hybrid quantum system consisting of a magnetic particle inductively coupled to two superconducting transmon qubits, where qubit-qubit interactions are mediated via magnons. We show that the system can be tuned into three…

For building a scalable quantum processor with superconducting qubits, ZZ interaction is of great concern because its residual has a crucial impact to two-qubit gate fidelity. Two-qubit gates with fidelity meeting the criterion of…

Quantum Physics · Physics 2024-09-12 Peng Zhao , Peng Xu , Dong Lan , Ji Chu , Xinsheng Tan , Haifeng Yu , Yang Yu

A neutral-atom system serves as a promising platform for realizing gate-based quantum computing because of its capability to trap and control several atomic qubits in different geometries and the ability to perform strong, long-range…

Quantum Physics · Physics 2023-01-18 Archismita Dalal , Barry C. Sanders

A possible building block for a scalable quantum computer has recently been demonstrated [M. Mariantoni et al., Science 334, 61 (2011)]. This architecture consists of superconducting qubits capacitively coupled both to individual memory…

We demonstrate a controlled-Z gate between capacitively coupled fluxonium qubits with transition frequencies $72.3~\textrm{MHz}$ and $136.3~\textrm{MHz}$. The gate is activated by a $61.6~\textrm{ns}$ long pulse at the frequency between…

Applications for noisy intermediate-scale quantum computing devices rely on the efficient entanglement of many qubits to reach a potential quantum advantage. Although entanglement is typically generated using two-qubit gates, direct control…

Quantum Physics · Physics 2023-04-18 Niklas J. Glaser , Federico Roy , Stefan Filipp

Enhancing the capabilities of superconducting quantum hardware, requires higher gate fidelities and lower crosstalk, particularly in larger scale devices, in which qubits are coupled to multiple neighbors. Progress towards both of these…

Quantum Physics · Physics 2023-12-22 Lukas Heunisch , Christopher Eichler , Michael J. Hartmann

Striving for higher gate fidelity is crucial not only for enhancing existing noisy intermediate-scale quantum (NISQ) devices but also for unleashing the potential of fault-tolerant quantum computation through quantum error correction. A…

Quantum Physics · Physics 2024-11-27 Rui Li , Kentaro Kubo , Yinghao Ho , Zhiguang Yan , Yasunobu Nakamura , Hayato Goto

Quantum computation requires the precise control of the evolution of a quantum system, typically through application of discrete quantum logic gates on a set of qubits. Here, we use the cross-resonance interaction to implement a gate…

Variational algorithms such as the Quantum Approximate Optimization Algorithm have attracted attention due to their potential for solving problems using near-term quantum computers. The $ZZ$ interaction typically generates the primitive…

Quantum Physics · Physics 2023-04-28 T. Mueller , T. Stollenwerk , D. Headley , M. Epping , F. K. Wilhelm

Engineering high-fidelity two-qubit gates is an indispensable step toward practical quantum computing. For superconducting quantum platforms, one important setback is the stray interaction between qubits, which causes significant coherent…

Quantum Physics · Physics 2024-09-06 Ziwen Huang , Taeyoon Kim , Tanay Roy , Yao Lu , Alexander Romanenko , Shaojiang Zhu , Anna Grassellino

We propose and demonstrate an architecture for fluxonium-fluxonium two-qubit gates mediated by transmon couplers (FTF, for fluxonium-transmon-fluxonium). Relative to architectures that exclusively rely on a direct coupling between fluxonium…

Superconducting qubits have achieved remarkable progress in gate fidelity and coherence, yet their typical nearest-neighbor connectivity presents constraints for implementing complex quantum circuits. Here, we introduce a cavity-mediated…

Quantum Physics · Physics 2026-02-10 Shinyoung Hwang , Sangyeon Lee , Eunjong Kim

Three-qubit gates can be constructed using combinations of single-qubit and two-qubit gates, making their independent realization unnecessary. However, direct implementation of three-qubit gates reduces the depth of quantum circuits,…

We propose a hybrid quantum computing architecture composed of alternating fluxonium and transmon qubits, that are coupled via transmon tunable couplers. We show that this system offers excellent scaling properties, characterized by…

We propose a simple scheme for generating a high-fidelity controlled-Z (CZ) gate in a three-component qubit/bus/qubit device. The corresponding tune/detune pulse is single-step, with a near-resonant constant undershoot between the 200 and…

Quantum Physics · Physics 2011-03-25 Andrei Galiautdinov

Overcoming the issue of qubit-frequency fluctuations is essential to realize stable and practical quantum computing with solid-state qubits. Static ZZ interaction, which causes a frequency shift of a qubit depending on the state of…

Quantum Physics · Physics 2024-01-08 Shu Watanabe , Yutaka Tabuchi , Kentaro Heya , Shuhei Tamate , Yasunobu Nakamura

Gate-tunable transmon qubits are based on quantum conductors used as weak links within hybrid Josephson junctions. These gatemons have been implemented in just a handful of systems, all relying on extended conductors, namely epitaxial…

Mesoscale and Nanoscale Physics · Physics 2025-08-29 H. Riechert , S. Annabi , A. Peugeot , H. Duprez , M. Hantute , K. Watanabe , T. Taniguchi , E. Arrighi , J. Griesmar , J. -D. Pillet , L. Bretheau

A double-transmon coupler (DTC) enables a fast, high-fidelity CZ gate between two highly detuned, fixed-frequency transmon qubits. Moreover, a recently proposed capacitively shunted DTC (CSDTC) realizes a small residual ZZ interaction over…

Quantum Physics · Physics 2026-05-01 Shinichi Inoue , Rui Li , Kentaro Kubo , Yinghao Ho , Yasunobu Nakamura , Hayato Goto