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Electron spin qubits in silicon are a promising platform for fault-tolerant quantum computing. Low-frequency noise, including nuclear spin fluctuations and charge noise, is a primary factor limiting gate fidelities. Suppressing this noise…

Mesoscale and Nanoscale Physics · Physics 2024-11-13 Ning Wang , Shao-Min Wang , Run-Ze Zhang , Jia-Min Kang , Wen-Long Lu , Hai-Ou Li , Gang Cao , Bao-Chuan Wang , Guo-Ping Guo

We take a bottom-up, first-principles approach to design a two-qubit gate between fluxonium qubits for minimal error, speed, and control simplicity. Our proposed architecture consists of two fluxoniums coupled via a linear resonator. Using…

Fluxonium qubits demonstrate exceptional potential for quantum processing; yet, realizing scalable architectures using them remains challenging. We propose a fluxonium-based square-grid design with fast $\sim63$~ns controlled-Z (CZ) gates,…

Quantum Physics · Physics 2025-12-25 Andrei A. Kugut , Grigoriy S. Mazhorin , Ilya A. Simakov

We introduce a superconducting qubit architecture that combines high-coherence qubits and tunable qubit-qubit coupling. With the ability to set the coupling to zero, we demonstrate that this architecture is protected from the frequency…

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

We propose a scheme to realize quantum controlled-Z (CZ) gates through single gradient metasurface. Using its unique parallel beam-splitting feature, i.e., a series of connected beam splitters with the same splitting ratio, one metasurface…

Quantum Physics · Physics 2024-05-17 Qi Liu , Yu Tian , Zhaohua Tian , Guixin Li , Xi-Feng Ren , Qihuang Gong , Ying Gu

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…

The native gate set is fundamental to the performance of quantum devices, as it governs the accuracy of basic quantum operations and dictates the complexity of implementing quantum algorithms. Traditional approaches to extending gate sets…

We present a native three-qubit entangling gate that exploits engineered interactions to realize control-control-target and control-target-target operations in a single coherent step. Unlike conventional decompositions into multiple…

Quantum Physics · Physics 2025-08-15 Xuexin Xu , Siyu Wang , Radhika Joshi , Rihan Hai , Mohammad H. Ansari

Creation and manipulation of entanglement with low error is essential in quantum information systems. In practice, two-qubit entangling gates constitute a dominant error source, limiting circuit depths and performance in fault-tolerant…

Giant atoms are quantum emitters coupled to waveguides at multiple, spatially separated points, enabling interference effects that fundamentally change their light-matter interactions. A notable consequence of the interference is the…

Quantum Physics · Physics 2026-03-30 Walter Rieck , Ariadna Soro , Anton Frisk Kockum , Guangze Chen

Quantum error correction (QEC) is one of the crucial building blocks for developing quantum computers that have significant potential for reaching a quantum advantage in applications. Prominent candidates for QEC are stabilizer codes for…

We apply the quantum optimal control theory based on the Krotov method to implement single-qubit $X$ and $Z$ gates and two-qubit CNOT gates for inductively coupled superconducting flux qubits with fixed qubit transition frequencies and…

Quantum Physics · Physics 2014-07-16 Shang-Yu Huang , Hsi-Sheng Goan

We experimentally demonstrate a parametric iSWAP gate in a superconducting circuit based on a tunable coupler for achieving a continuous tunability to eliminate unwanted qubit interactions. We implement the twoqubit iSWAP gate by applying a…

Quantum Physics · Physics 2020-09-02 X. Y. Han , T. Q. Cai , X. G. Li , Y. K. Wu , Y. W. Ma , Y. L. Ma , J. H. Wang , H. Y. Zhang , Y. P. Song , L. M. Duan

Efficient decompositions of multi-qubit gates are essential in NISQ applications, where the number of gates or the circuit depth is limited. This paper presents efficient decompositions of CCZ and CCCZ gates, typical multi-qubit gates,…

Quantum Physics · Physics 2021-09-28 Ken M. Nakanishi , Takahiko Satoh , Synge Todo

In this paper, we examine various software and hardware strategies for implementing high-fidelity controlled-Z gate in the large-scale quantum system by solving the system's Hamiltonian with the Lindblad master equation. First, we show that…

Quantum Physics · Physics 2022-12-09 Dowon Baek , Seong Hyeon Park , Suhwan Choi , Chanwoo Yoo , Seungyong Hahn

High-fidelity parametric gates have been demonstrated with superconducting qubits via rf flux modulation of the qubit frequency. The modulation however leads to renormalization of the bare qubit-qubit coupling, thereby reducing the gate…

In superconducting quantum processors, exploring diverse control methods could offer essential versatility and redundancy to mitigate challenges such as frequency crowding, spurious couplings, control crosstalk, and fabrication variability,…

Quantum Physics · Physics 2026-02-13 Peng Zhao , Peng Xu , Zheng-Yuan Xue

We present a unified scheme for generating high-fidelity entangling gates in superconducting platforms by continuous dynamical decoupling (CDD) combined with variational minimal-energy optimal control. During the CDD stage, we suppress…