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Quantum coherence is an essential ingredient in quantum information processing and plays a central role in emergent fields such as nanoscale thermodynamics and quantum biology. However, our understanding and quantitative characterization of…

One of the most widespread methods to determine if a quantum state is entangled, or to quantify its entanglement dimensionality, is by measuring its fidelity with respect to a pure state. In this Letter we find a large class of states whose…

Quantum Physics · Physics 2020-08-14 Mirjam Weilenmann , Benjamin Dive , David Trillo , Edgar A. Aguilar , Miguel Navascués

One of the biggest problems in the theory of quantum information is the quantification of amount of entanglement in an arbitrary multipartite mixed state. Different axiomatic and operational measures were proposed so far. In this work we…

Quantum Physics · Physics 2009-11-11 Alexander Streltsov

Quantum computers will require encoding of quantum information to protect them from noise. Fault-tolerant quantum computing architectures illustrate how this might be done but have not yet shown a conclusive practical advantage. Here we…

Quantum Physics · Physics 2019-03-01 Robin Harper , Steven T. Flammia

The implementation of quantum gates with fidelities that exceed the threshold for reliable quantum computing requires robust gates whose performance is not limited by the precision of the available control fields. The performance of these…

Quantum Physics · Physics 2015-12-30 Alexandre M. Souza , Roberto S. Sarthour , Ivan S. Oliveira , Dieter Suter

Accurate quantum computing relies on the precision of quantum gates. However, quantum gates in practice are generally affected by dissipative environments, which can significantly reduce their fidelity. In this study, we elucidate…

Quantum Physics · Physics 2024-09-02 Tan Van Vu , Tomotaka Kuwahara , Keiji Saito

A scheme to evaluate computation fidelities within the one-way model is developed and explored to understand the role of correlations in the quality of noisy quantum computations. The formalism is promptly applied to many computation…

Quantum Physics · Physics 2013-05-29 Rafael Chaves , Fernando de Melo

Fault-tolerant quantum computing requires gates which function correctly despite the presence of errors, and are scalable if the error probability-per-gate is below a threshold value. To date, no method has been described for calculating…

The fidelity of entangling operations is a key figure of merit in quantum information processing, especially in the context of quantum error correction. High-fidelity entangling gates in neutral atoms have seen remarkable advancement…

Quantum Physics · Physics 2025-02-21 Richard Bing-Shiun Tsai , Xiangkai Sun , Adam L. Shaw , Ran Finkelstein , Manuel Endres

We propose a quantum error mitigation scheme for single-qubit measurement errors, particularly suited for one-way quantum computation. Contrary to well established error mitigation methods for circuit-based quantum computation, that require…

Quantum Physics · Physics 2024-11-15 Tobias Hartung , Stephan Schuster , Joachim von Zanthier , Karl Jansen

We propose a method of manipulating a quantum register remotely with the help of a single ancilla that steers the evolution of the register. The fully controlled ancilla qubit is coupled to the computational register solely via a fixed…

Quantum Physics · Physics 2010-08-12 Janet Anders , Daniel K. L. Oi , Elham Kashefi , Dan E. Browne , Erika Andersson

Large weak values have been used to amplify the sensitivity of a linear response signal for detecting changes in a small parameter, which has also enabled a simple method for precise parameter estimation. However, producing a large weak…

Quantum Physics · Physics 2014-07-23 Shengshi Pang , Justin Dressel , Todd A. Brun

Characterizing entanglement in all but the simplest case of a two qubit pure state is a hard problem, even understanding the relevant experimental quantities that are related to entanglement is difficult. It may not be necessary, however,…

Quantum Physics · Physics 2015-06-26 J. Grondalski , D. M. Etlinger , D. F. V. James

Quantum entanglement is a unique criterion of the quantum realm and an essential tool to secure quantum communication. Ensuring high-fidelity entanglement has always been a challenging task owing to interaction with the hostile channel…

Quantum Physics · Physics 2025-07-23 Syed Emad Uddin Shubha , Md. Saifur Rahman , M. R. C. Mahdy

Trapped-ion has shown great advantages in building quantum computers. While high fidelity entangling-gate has been realized for few ions, how to maintain the high fidelity for large scale trapped-ions still remains an open problem.Here, we…

Quantum Physics · Physics 2023-05-11 Wenhao He , Wenhao Zhang , Xiao Yuan , Yangchao Shen , Xiao-Ming Zhang

We show the equivalence of two different notions of quantum channel capacity: that which uses the entanglement fidelity as its criterion of success in transmission, and that which uses the minimum fidelity of pure states in a subspace of…

Quantum Physics · Physics 2016-11-18 H. Barnum , E. Knill , M. A. Nielsen

Working with trapped atoms at close distance to each other, we show that one can implement entangling gates based on non-independent qubits using a single pulse per qubit, or a single structured pulse. The optimal parameters depend on…

Quantum Physics · Physics 2023-10-19 Ignacio R. Sola , Seokmin Shin , Bo Y. Chang

Entangled coherent states can be used to determine the entanglement fidelity for a device that is designed to teleport coherent states. This entanglement fidelity is universal, in that the calculation is independent of the use of entangled…

Quantum Physics · Physics 2007-05-23 Tyler J. Johnson , Stephen D. Bartlett , Barry C. Sanders

We characterise a model of universal quantum computation where the register (computational) qubits are controlled by ancillary qubits, using only a single fixed interaction between register and ancillary qubits. No additional access is…

Quantum Physics · Physics 2013-10-25 Timothy J. Proctor , Erika Andersson , Viv Kendon

We study the performance of simple quantum error correcting codes with respect to correlated noise errors characterized by a finite correlation strength. Specifically, we consider bit flip (phase flip) noisy quantum memory channels and use…

Quantum Physics · Physics 2015-05-13 Carlo Cafaro , Stefano Mancini