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Transversal gates are the ideal gates in a fault-tolerant scenario; relatively easy to implement, and minimally error propagating. Their availability will maximise fault tolerant thresholds, enabling universal quantum computation in a wider…

Quantum Physics · Physics 2025-06-23 Heather Leitch , Alastair Kay

Dephasing -- phase randomization of a quantum superposition state -- is a major obstacle for the realization of high fidelity quantum logic operations. Here, we implement a two-qubit Controlled-NOT gate using dynamical decoupling (DD),…

Quantum Physics · Physics 2013-07-17 Ch. Piltz , B. Scharfenberger , A. Khromova , A. F. Varón , Ch. Wunderlich

We analyze the accuracy of quantum phase gates acting on "0-$\pi$ qubits" in superconducting circuits, where the gates are protected against thermal and Hamiltonian noise by continuous-variable quantum error-correcting codes. The gates are…

Quantum Physics · Physics 2020-07-24 Peter Brooks , Alexei Kitaev , John Preskill

Nearly all modern solid-state quantum processors approach quantum computation with a set of discrete qubit operations (gates) that can achieve universal quantum control with only a handful of primitive gates. In principle, this approach is…

The realization of fault-tolerant quantum computation hinges on the ability to execute deep quantum circuits while maintaining gate fidelities consistently above error-correction thresholds. Although neutral-atom arrays have recently…

Quantum holonomic gates hold built-in resilience to local noises and provide a promising approach for implementing fault-tolerant quantum computation. We propose to realize high-fidelity holonomic $(N+1)$-qubit controlled gates using…

Quantum Physics · Physics 2021-11-18 Jin-Lei Wu , Yan Wang , Jin-Xuan Han , Yongyuan Jiang , Jie Song , Yan Xia , Shi-Lei Su , Weibin Li

As quantum circuits become more integrated and complex, additional error sources that were previously insignificant start to emerge. Consequently, the fidelity of quantum gates benchmarked under pristine conditions falls short of predicting…

Robust qubit-qubit interactions mediated by bosonic modes are central to many quantum technologies. Existing proposals combining fast oscillator-mediated gates with dynamical decoupling require strong pulses or fast control over the…

Quantum Physics · Physics 2023-05-31 I. Arrazola , J. Casanova

Since the first demonstration of coherent control of a quantum state of a superconducting charge qubit a variety of Josephson-junction-based qubits have been implemented with remarkable progress in coherence time and read-out schemes.…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 T. Yamamoto , Yu. A. Pashkin , O. Astafiev , Y. Nakamura , J. S. Tsai

Implementation of quantum logic gates with linear optical elements plays a prominent role in quantum computing due to the relatively easier manipulation and realization. We present efficient schemes to implement controlled-NOT (CNOT) gate…

Quantum Physics · Physics 2026-02-11 Gui-Long Jiang , Jun-Bin Yuan , Wen-Qiang Liu , Hai-Rui Wei

The rapid growth in size of quantum devices demands efficient ways to control them, which is challenging for systems with thousands of qubits or more. Here, we present a simple yet powerful solution: robust, site-dependent control of an…

Quantum Physics · Physics 2023-12-15 Wenjie Gong , Soonwon Choi

The central challenge of quantum computing is implementing high-fidelity quantum gates at scale. However, many existing approaches to qubit control suffer from a scale-performance trade-off, impeding progress towards the creation of useful…

Two qubit gates constitute fundamental building blocks in the realization of large-scale quantum devices. Using superconducting circuits, two-qubit gates have previously been implemented in different ways with each method aiming to maximize…

Fast, high fidelity control and readout of protected superconducting qubits are fundamentally challenging due to their inherent insensitivity. We propose a flux qubit variation which enjoys a tunable level of protection against relaxation…

Control over physical systems at the quantum level is a goal shared by scientists in fields as diverse as metrology, information processing, simulation and chemistry. For trapped atomic ions, the quantized motional and internal degrees of…

Quantum Physics · Physics 2015-03-19 C. Ospelkaus , U. Warring , Y. Colombe , K. R. Brown , J. M. Amini , D. Leibfried , D. J. Wineland

Optimization of the fidelity of control operations is of critical importance in the pursuit of fault-tolerant quantum computation. We apply optimal control techniques to demonstrate that a single drive via the cavity in circuit quantum…

Quantum Physics · Physics 2017-04-20 Joseph L. Allen , Robert Kosut , Jaewoo Joo , Peter Leek , Eran Ginossar

We present a method of implementing ultrafast two-qubit gates valid for the ultrastrong coupling (USC) and deep strong coupling (DSC) regimes of light-matter interaction, considering state-of-the-art circuit quantum electrodynamics (QED)…

Quantum Physics · Physics 2015-05-30 G. Romero , D. Ballester , Y. M. Wang , V. Scarani , E. Solano

The increasing number of qubits in quantum processors necessitates a corresponding increase in the number of control lines between the processor, which is typically operated at cryogenic temperatures, and external electronics. Scaling poses…

Quantum Physics · Physics 2026-04-17 Haruki Mitarai , Yukihiro Tadokoro , Hiroya Tanaka

We experimentally demonstrate quantum process tomography of controlled-Z and controlled-NOT gates using capacitively-coupled superconducting phase qubits. These gates are realized by using the $|2\rangle$ state of the phase qubit. We obtain…

Increasing quantum circuit fidelity requires an efficient instruction set to avoid errors from decoherence. The choice of a two-qubit (2Q) hardware basis gate depends on a quantum modulator's native Hamiltonian interactions and applied…

Quantum Physics · Physics 2025-04-22 Evan McKinney , Chao Zhou , Mingkang Xia , Michael Hatridge , Alex K. Jones