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Hardware efficient transpilation of quantum circuits to a quantum devices native gateset is essential for the execution of quantum algorithms on noisy quantum computers. Typical quantum devices utilize a gateset with a single two-qubit…

We propose a superconducting qubit based on engineering the first and second harmonics of the Josephson energy and phase relation $E_{J1}\cos \varphi$ and $E_{J2}\cos 2\varphi$. By constructing a circuit such that $E_{J2}$ is negative and…

Quantum Physics · Physics 2025-02-24 Max Hays , Junghyun Kim , William D. Oliver

We show that all Clifford circuits under interspersed depolarizing noise lose memory of their input exponentially quickly, even when given access to a constant supply of fresh qubits in arbitrary states. This is somewhat surprising given…

Quantum Physics · Physics 2025-10-10 Jon Nelson , Joel Rajakumar , Michael J. Gullans

We propose a novel architecture that utilizes two 0-$\pi$ qubits based on topological Josephson junctions to implement a parity-protected superconducting qubit. The topological Josephson junctions provides protection against fabrication…

Mesoscale and Nanoscale Physics · Physics 2026-01-06 Guo-Liang Guo , Han-Bing Leng , Xin Liu

A two-qubit controlled-NOT (CNOT) gate, realized by a controlled-phase (C-phase) gate combined with single-qubit gates, has been experimentally implemented recently for quantum-dot spin qubits in isotopically enriched silicon, a promising…

Quantum Physics · Physics 2019-04-05 Chia-Hsien Huang , C. H. Yang , Chien-Chang Chen , A. S. Dzurak , Hsi-Sheng Goan

Superconducting quantum circuits based on Josephson junctions have made rapid progress in demonstrating quantum behavior and scalability. However, the future prospects ultimately depend upon the intrinsic coherence of Josephson junctions,…

Superconducting protected qubits aim to achieve sufficiently low error rates so as to allow realization of error-corrected, utility-scale quantum computers. A recent proposal encodes a protected qubit in the quasicharge degree of freedom of…

Quantum Physics · Physics 2026-01-09 Nicholas M. Christopher , Deniz E. Stiegemann , Abhijeet Alase , Thomas M. Stace

We propose a scheme for the fault-tolerant implementation of arbitrary Clifford circuits. To achieve this, we extend previous work on flag gadgets for syndrome extraction to a general framework that flags any Clifford circuit. This…

Quantum Physics · Physics 2025-10-10 Benjamin Anker , Milad Marvian

The Gottesman-Kitaev-Preskill (GKP) code is an exciting route to fault-tolerant quantum computing since Gaussian resources and GKP Pauli-eigenstate preparation are sufficient to achieve universal quantum computing. In this work, we provide…

Quantum Physics · Physics 2024-04-08 Mackenzie H. Shaw , Andrew C. Doherty , Arne L. Grimsmo

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

The development of quantum circuits based on hybrid superconductor-semiconductor Josephson junctions holds promise for exploring their mesoscopic physics and for building novel superconducting devices. The gate-tunable superconducting…

We develop a family of quantum accreditation protocols for quantum circuits with non-Clifford two-qubit gates. The latter includes families of gates such as the fSim and XY families of gates, native to existing hardwares. We provide…

Quantum Physics · Physics 2026-05-20 Andrew Jackson , Theodoros Kapourniotis , Animesh Datta

We explore the implementation of pseudo-random single-qubit rotations and multi-qubit pseudo-random circuits constructed only from Clifford gates and the T-gate, a phase rotation of pi/4. Such a gate set would be appropriate for…

Quantum Physics · Physics 2015-06-17 Yaakov S. Weinstein

We propose a family of explicit geometrically local circuits on a 2-dimensional planar grid of qudits, realizing any abelian non-chiral topological phase as an actively error-corrected fault-tolerant memory. These circuits are constructed…

Quantum Physics · Physics 2025-03-26 Andreas Bauer

We report the achievement of single-qubit gates with sub-part-per-million error rates, in a trapped-ion $^{43}$Ca$^{+}$ hyperfine clock qubit. We explore the speed/fidelity trade-off for gate times $4.4\leq t_{g}\leq35~\mu$s, and benchmark…

Quantum Physics · Physics 2025-06-16 M. C. Smith , A. D. Leu , K. Miyanishi , M. F. Gely , D. M. Lucas

We propose a protected qubit based on a modular array of superconducting islands connected by semiconductor Josephson interferometers. The individual interferometers realize effective $\cos2\phi$ elements that exchange `pairs of Cooper…

Quantum Physics · Physics 2022-12-02 Constantin Schrade , Charles M. Marcus , András Gyenis

Quantum gates based on geometric phases possess intrinsic noise-resilience features and therefore attract much attention. However, the implementations of previous geometric quantum computation typically require a long pulse time of gates.…

Quantum Physics · Physics 2022-10-10 Zhuang Ma , Jianwen Xu , Tao Chen , Yu Zhang , Wen Zheng , Dong Lan , Zheng-Yuan Xue , Xinsheng Tan , Yang Yu

Obtaining high-fidelity and robust quantum gates is the key for scalable quantum computation, and one of the promising ways is to implement quantum gates using geometric phases, where the influence of local noises can be greatly reduced. To…

Quantum Physics · Physics 2021-10-07 Zhi-Cheng He , Zheng-Yuan Xue

We propose a heralded protocol for implementing nontrivial quantum gates on two stationary qubits coupled to spatially separated cavities. By dynamically controlling the evolution of the composite system, nonlocal two-qubit quantum (e.g.,…

Quantum Physics · Physics 2024-11-26 Wanhua Su , Wei Qin , Adam Miranowicz , Tao Li , Franco Nori

Controlling the energy spectrum of quantum-coherent superconducting circuits, i.e. the energies of excited states, the circuit anharmonicity and the states' charge dispersion, is essential for designing performant qubits. This control is…