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Continuous gate sets are a key ingredient for near-term quantum algorithms. Here, we demonstrate a hardware-efficient, continuous set of controlled arbitrary-phase ($\mathrm{C}Z_{\theta}$) gates acting on flux-tunable transmon qubits. This…

Ternary quantum information processing in superconducting devices poses a promising alternative to its more popular binary counterpart through larger, more connected computational spaces and proposed advantages in quantum simulation and…

We introduce a novel quantum control method for superconducting transmon qubits that substantially outperforms conventional techniques in precision and robustness against coherent errors. Our approach leverages composite pulses (CP) to…

Quantum Physics · Physics 2025-06-10 Hristo G. Tonchev , Boyan T. Torosov , Nikolay V. Vitanov

Implementation of high-fidelity two-qubit operations is a key ingredient for scalable quantum error correction. In superconducting qubit architectures tunable buses have been explored as a means to higher fidelity gates. However, these…

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

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

Controllable interaction between superconducting qubits is desirable for large-scale quantum computation and simulation. Here, based on a theoretical proposal by Yan et al. [Phys. Rev. Appl. 10, 054061 (2018)] we experimentally demonstrate…

Quantum Physics · Physics 2020-09-15 X. Li , T. Cai , H. Yan , Z. Wang , X. Pan , Y. Ma , W. Cai , J. Han , Z. Hua , X. Han , Y. Wu , H. Zhang , H. Wang , Yipu Song , Luming Duan , Luyan Sun

The design of coupler-based superconducting two-qubit gates simplifies circuit layout and alleviate frequency crowding, thereby enhancing the scalability and flexibility of quantum chips. However, in such architectures, a trade-off often…

Quantum Physics · Physics 2026-04-13 Bo-Xun Deng , Jia-Qi Hu , Cheng-Yun Ding , Zheng-Yuan Xue , Tao Chen

Generating high-fidelity, tunable entanglement between qubits is crucial for realizing gate-based quantum computation. In superconducting circuits, tunable interactions are often implemented using flux-tunable qubits or coupling elements,…

Increasing the fidelity of single-qubit gates requires a combination of faster pulses and increased qubit coherence. However, with resonant qubit drive via a capacitively coupled port, these two objectives are mutually contradictory, as…

A challenge for constructing large circuits of superconducting qubits is to balance addressability, coherence and coupling strength. High coherence can be attained by building circuits from fixed-frequency qubits, however, leading…

Tunable couplers in superconducting qubit architectures enable strong qubit-qubit interactions for two-qubit gates while suppressing unwanted coupling during single-qubit operations. However, achieving low error rates for fast two-qubit…

Quantum Physics · Physics 2026-04-08 Angela Q. Chen , Xian Wu , Sarah Strong , Stefano Poletto

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…

Scalable superconducting quantum processors require balancing critical constraints in coherence, control complexity, and spectral crowding. Fixed-frequency architectures suppress flux noise and simplify control via all-microwave operations…

Quantum Physics · Physics 2025-10-17 Kui Zhao , Wei-Guo Ma , Ziting Wang , Hao Li , Kaixuan Huang , Yun-Hao Shi , Kai Xu , Heng Fan

As systems for quantum computing keep growing in size and number of qubits, challenges in scaling the control capabilities are becoming increasingly relevant. Efficient schemes to simultaneously mediate coherent interactions between…

A common approach to realize conditional-phase (CZ) gates in transmon qubits relies on flux control of the qubit frequency to make computational states interact with non-computational ones using a fast-adiabatic trajectory to minimize…

We demonstrate fast two-qubit gates using a parity-violated superconducting qubit consisting of a capacitively-shunted asymmetric Josephson-junction loop under a finite magnetic flux bias. The second-order nonlinearity manifesting in the…

Superconducting transmon qubits comprise one of the most promising platforms for quantum information processing due to their long coherence times and to their scalability into larger qubit networks. However, their weakly anharmonic spectrum…

Mesoscale and Nanoscale Physics · Physics 2017-08-02 Xiu-Hao Deng , Edwin Barnes , Sophia E. Economou

We analyze a high-fidelity two-qubit gate using fast flux pulses on superconducting fluxonium qubits. The gate is realized by temporarily detuning magnetic flux through fluxonium loop away from the half flux quantum sweet spot. We simulate…

Quantum Physics · Physics 2022-09-28 Yinqi Chen , Konstantin N. Nesterov , Vladimir E. Manucharyan , Maxim G. Vavilov