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We explore the feasibility of fault-tolerant quantum computation using the bit-flip repetition code in a biased noise channel where only the bit-flip error can occur. While several logic gates can potentially produce phase-flip errors even…

Quantum Physics · Physics 2024-06-26 Shoichiro Tsutsui , Keita Kanno

Coherent gate errors are a concern in many proposed quantum computing architectures. These errors can be effectively handled through composite pulse sequences for single-qubit gates, however, such techniques are less feasible for entangling…

The ultimate accuracy as regards controlling a qubit with a coherent field is studied in terms of degradation of the fidelity by employing a fully quantum mechanical treatment. While the fidelity error accompanied by pi/2 pulse control is…

Quantum Physics · Physics 2015-06-12 Kazuhiro Igeta , Nobuyuki Imoto , Masato Koashi

We demonstrate high-fidelity single-qubit gates on a C-shunt flux qubit that simultaneously combines a large anharmonicity ($\mathcal{A}/2\pi=848~\mathrm{MHz}$) with long relaxation time ($T_1 = 23~\mu\text{s}$). The large anharmonicity…

Superconducting qubits offer an unprecedentedly high degree of flexibility in terms of circuit encoding and parameter choices. However, in designing the qubit parameters one typically faces the conflicting goals of long coherence times and…

Quantum Physics · Physics 2025-04-08 C. A. Siegele , A. A. Sokolova , L. N. Kapoor , F. Hassani , J. M. Fink

Noise remains one of the most significant challenges in the development of reliable and scalable quantum processors. While quantum error correction and mitigation techniques offer potential solutions, they are often limited by the…

Quantum Physics · Physics 2025-06-11 Mathys Rennela , Harold Ollivier

We have designed efficient quantum circuits for the three-qubit Toffoli (controlled-controlled NOT) and the Fredkin (controlled-SWAP) gate, optimized via genetic programming methods. The gates thus obtained were experimentally implemented…

Quantum Physics · Physics 2018-02-13 Amit Devra , Prithviraj Prabhu , Harpreet Singh , Arvind , Kavita Dorai

Near-term quantum computations are limited by high error rates, the scarcity of qubits and low qubit connectivity. Increasing support for mid-circuit measurements and qubit reset in near-term quantum computers enables qubit reuse that may…

Quantum Physics · Physics 2023-08-02 Sebastian Brandhofer , Ilia Polian , Kevin Krsulich

The surface code is one the most promising alternatives for implementing fault-tolerant, large-scale quantum information processing. Its high threshold for single-qubit errors under stochastic noise is one of its most attrative features. We…

Quantum Physics · Physics 2014-10-29 Pejman Jouzdani , E. Novais , I. S. Tupitsyn , Eduardo R. Mucciolo

An average gate fidelity is a standard performance metric to quantify deviation between an ideal unitary gate transformation and its realistic experimental implementation. The average is taken with respect to states uniformly distributed…

Quantum Physics · Physics 2020-11-13 Filip Wudarski , Jeffrey Marshall , Andre Petukhov , Eleanor Rieffel

Successful implementations of quantum technologies require protocols and algorithms that use as few quantum resources as possible. However, many important quantum operations, such as continuous rotation gates in quantum computing or…

Quantum Physics · Physics 2025-01-09 Bálint Koczor

Gate-defined semiconductor quantum dots utilize fast electrical control to manipulate spin and charge states of individual electrons. Electrical pulse distortions can limit control fidelities but are difficult to measure at the device…

Quantum Physics · Physics 2026-02-23 Jiheng Duan , Fernando Torres-Leal , John M. Nichol

Singlet-triplet qubits in lateral quantum dots in semiconductor heterostructures exhibit high-fidelity single-qubit gates via exchange interactions and magnetic field gradients. High-fidelity two-qubit entangling gates are challenging to…

Mesoscale and Nanoscale Physics · Physics 2017-12-06 M. A. Wolfe , F. A. Calderon-Vargas , J. P. Kestner

We present an iterative optimal control method of quantum systems, aimed at an implementation of a desired operation with optimal fidelity. The update step of the method is based on the linear response of the fidelity to the control…

Quantum Physics · Physics 2025-02-06 Nicolas Heimann , Lukas Broers , Ludwig Mathey

We present measurements of single-qubit gate errors for a superconducting qubit. Results from quantum process tomography and randomized benchmarking are compared with gate errors obtained from a double pi pulse experiment. Randomized…

Mesoscale and Nanoscale Physics · Physics 2009-03-08 J. M. Chow , J. M. Gambetta , L. Tornberg , Jens Koch , Lev S. Bishop , A. A. Houck , B. R. Johnson , L. Frunzio , S. M. Girvin , R. J. Schoelkopf

In this study, we examine decoherence of qubits system coupled independently by using influence functional. We especially concentrated on the effect of qubit flip process. We examine the zero-dimensional qubit and one-dimensional qubits…

Quantum Physics · Physics 2008-09-30 Toshifumi Itakura

Qubit decoherence unavoidably degrades the fidelity of quantum logic gates. Accordingly, realizing gates that are as fast as possible is a guiding principle for qubit control, necessitating protocols for mitigating error channels that…

Accurate and efficient implementation of parallel quantum gates is crucial for scalable quantum information processing. However, the unavoidable crosstalk between qubits in current noisy processors impedes the achievement of high gate…

Quantum Physics · Physics 2026-01-06 Xiaodong Yang , Ran Liu , Jun Li

We formulate a scheme for fault-tolerant quantum computation that works effectively against highly biased noise, where dephasing is far stronger than all other types of noise. In our scheme, the fundamental operations performed by the…

Quantum Physics · Physics 2008-11-21 Panos Aliferis , John Preskill

Optically trapped polar molecules are promising for quantum information processing, yet the accuracy of an entangling molecular gate is limited by the uncertainty of dipole-dipole interactions~(DDI) from the molecular motion in traps. We…

Quantum Physics · Physics 2026-05-20 Yan Lu , Xiao-Feng Shi