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We derive an experimentally testable criterion for the teleportation of quantum states of continuous variables. This criterion is especially relevant to the recent experiment of Furusawa et al. [Science 282, 706-709 (1998)] where an…

Quantum Physics · Physics 2015-06-26 Samuel L. Braunstein , Christopher A. Fuchs , H. J. Kimble

Performance of quantum teleportation is typically measured by the average fidelity, an overlap between the input and output states. Along with the first moment, we introduce the second moment of fidelity in CV teleportation, i.e., the…

Quantum Physics · Physics 2022-09-16 Ayan Patra , Rivu Gupta , Saptarshi Roy , Aditi Sen De

Realistic fault-tolerant quantum computing at reasonable overhead requires two-qubit gates with the highest possible fidelity. Typically, an infidelity of $\lesssim 10^{-4}$ is recommended in the literature. Focusing on the phase-sensitive…

Quantum Physics · Physics 2023-11-28 Reinhold Blümel , Andrii Maksymov , Ming Li

Continuous variable quantum key distribution (CV-QKD), utilizes continuous variables encoding such as the quadra-ture components of the quantized electromagnetic field and coherent detection decoding, offering good compatibility with the…

Quantum Physics · Physics 2025-07-22 Pu Wang , Yan Tian , Yongmin Li

The fidelity function of quantum states have been widely used in quantum information science and frequently arises in the quantification of optimal performances for the estimation and distinguish of quantum states. A fidelity function on…

Quantum Physics · Physics 2017-03-09 Haidong Yuan , Chi-Hang Fred Fung

We experimentally address the significance of fidelity as a figure of merit in quantum state reconstruction of discrete (DV) and continuous variable (CV) quantum optical systems. In particular, we analyze the use of fidelity in quantum…

Quantum processors can already execute tasks beyond the reach of classical simulation, albeit for artificial problems. At this point, it is essential to design error metrics that test the experimental accuracy of quantum algorithms with…

Quantum Physics · Physics 2024-01-22 Jader P. Santos , Ivan Henao , Raam Uzdin

Continuous variable (CV) quantum computation offers an alternative to qubit-based computing by exploiting the infinite-dimensional Hilbert space of bosonic modes. Despite recent progress, superconducting platforms have yet to demonstrate a…

Continuous-variable (CV) quantum computing offers a promising framework for scalable quantum machine learning, leveraging optical systems with infinite-dimensional Hilbert spaces. While discrete-variable (DV) quantum neural networks have…

Quantum Physics · Physics 2025-11-05 Daniel Alejandro Lopez , Oscar Montiel , Oscar Castillo , Miguel Lopez-Montiel

Determining the optimal fidelity for the transmission of quantum information over noisy quantum channels is one of the central problems in quantum information theory. Recently, [Berta-Borderi-Fawzi-Scholz, Mathematical Programming, 2021]…

Quantum Physics · Physics 2026-04-21 Yeow Meng Chee , Hoang Ta , Van Khu Vu

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

We propose a fidelity measure for quantum channels in a straightforward analogy to the corresponding mixed-state fidelity of Jozsa. We describe properties of this fidelity measure and discuss some applications of it to quantum information…

Quantum Physics · Physics 2007-05-23 Maxim Raginsky

Quantum gates in experiment are inherently prone to errors that need to be characterized before they can be corrected. Full characterization via quantum process tomography is impractical and often unnecessary. For most practical purposes,…

Quantum channels depending on a number of classical control parameters are considered. Assuming the stochastic fluctuations of the control parameters in the small errors limit it is shown that the channel fidelity is equal to the average…

Quantum Physics · Physics 2007-05-23 A. V. Kuzmin

A generic model of measurement device which is able to directly measure commonly used quantum-state characteristics such as fidelity, overlap, purity and Hilbert-Schmidt distance for two general uncorrelated mixed states is proposed. In…

Quantum Physics · Physics 2009-11-07 Radim Filip

We provide a security analysis for continuous variable quantum key distribution protocols based on the transmission of squeezed vacuum states measured via homodyne detection. We employ a version of the entropic uncertainty relation for…

We present examples of continuous variable (CV) states having high fidelity to a given target, say $F > 0.9$ or $F > 0.99$, and still showing striking differences in their physical properties, including classical and quantum states within…

Quantum Physics · Physics 2014-07-03 Antonio Mandarino , Matteo Bina , Stefano Olivares , Matteo G. A. Paris

Remarkable experimental advances in quantum computing are exemplified by recent announcements of impressive average gate fidelities exceeding 99.9% for single-qubit gates and 99% for two-qubit gates. Although these high numbers engender…

Quantum Physics · Physics 2015-12-29 Yuval R Sanders , Joel J Wallman , Barry C Sanders

We present a rigorous security analysis of Continuous-Variable Measurement-Device Independent Quantum Key Distribution (CV MDI QKD) in a finite size scenario. The security proof is obtained in two steps: by first assessing the security…

Quantum Physics · Physics 2018-06-12 Cosmo Lupo , Carlo Ottaviani , Panagiotis Papanastasiou , Stefano Pirandola

We describe a scalable stochastic method for the experimental measurement of generalized fidelities characterizing the accuracy of the implementation of a coherent quantum transformation. The method is based on the motion reversal of random…

Quantum Physics · Physics 2009-11-11 Joseph Emerson , Robert Alicki , Karol Zyczkowski