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This paper investigates the state estimation problem for a class of complex networks, in which the dynamics of each node is subject to Gaussian noise, system uncertainties and nonlinearities. Based on a regularized least-squares approach,…

Systems and Control · Electrical Eng. & Systems 2021-03-16 Peihu Duan , Qishao Wang , Zhisheng Duan , Guanrong Chen

Testing graph completeness is a critical problem in computer science and network theory. Leveraging quantum computation, we present an efficient algorithm using the Szegedy quantum walk and quantum phase estimation (QPE). Our algorithm,…

Quantum Physics · Physics 2025-11-26 Sara Giordano , Miguel A. Martin-Delgado

The unavoidable finite time intervals between the sequential operations needed for performing practical quantum computing can degrade the performance of quantum computers. During these delays, unwanted relative dynamical phases are produced…

Quantum Physics · Physics 2009-11-10 L. F. Wei , Franco Nori

We investigate the problem of jointly testing multiple hypotheses and estimating a random parameter of the underlying distribution in a sequential setup. The aim is to jointly infer the true hypothesis and the true parameter while using on…

Signal Processing · Electrical Eng. & Systems 2024-02-02 Dominik Reinhard , Michael Fauß , Abdelhak M. Zoubir

We study manipulation of entanglement between two identical networks of quantum mechanical particles. Firstly, we reduce the problem of entanglement transfer to the problem of quantum state transfer. Then, we consider entanglement…

Quantum Physics · Physics 2011-01-27 Andrea Casaccino , Stefano Mancini , Simone Severini

We present a scheme for simulating the quantum network of quantum estimation proposed by A. K. Ekert et al. [Phys. Rev. Lett. 88, 217901 (2002)]. We experimentally implement the scheme with linear optical elements. We perform overlap…

Quantum Physics · Physics 2007-05-23 Zhi-Wei Wang , Jian Li , Yun-Feng Huang , Yong-Sheng Zhang , Xi-Feng Ren , Pei Zhang , Guang-Can Guo

Quantum-phase-estimation algorithms are critical subroutines in many applications for quantum computers and in quantum-metrology protocols. These algorithms estimate the unknown strength of a unitary evolution. By using coherence or…

Quantum Physics · Physics 2023-03-06 Joseph G. Smith , Crispin H. W. Barnes , David R. M. Arvidsson-Shukur

We derive a family of optimal protocols, in the sense of saturating the quantum Cram\'{e}r-Rao bound, for measuring a linear combination of $d$ field amplitudes with quantum sensor networks, a key subprotocol of general quantum sensor…

Quantum Physics · Physics 2023-10-03 Adam Ehrenberg , Jacob Bringewatt , Alexey V. Gorshkov

We address the experimental determination of entanglement for systems made of a pair of polarization qubits. We exploit quantum estimation theory to derive optimal estimators, which are then implemented to achieve ultimate bound to…

Quantum Physics · Physics 2015-05-27 G. Brida , I. P. Degiovanni , A. Florio , M. Genovese , P. Giorda , A. Meda , M. G. A. Paris , A. Shurupov

One of the main quests in quantum metrology, and quantum parameter estimation in general, is to find out the highest achievable precision with given resources and design schemes that attain that precision. In this article we present a…

Quantum Physics · Physics 2016-05-23 Haidong Yuan , Chi-Hang Fred Fung

We propose a quantum machine learning algorithm for efficiently solving a class of problems encoded in quantum controlled unitary operations. The central physical mechanism of the protocol is the iteration of a quantum time-delayed equation…

This thesis seeks to develop a general method for solving so-called quantum realizability problems, which are questions of the following form: under which conditions does there exist a quantum state exhibiting a given collection of…

Quantum Physics · Physics 2024-02-20 Thomas C. Fraser

Quantum entanglement distribution between remote nodes is key to many promising quantum applications. Existing mechanisms have mainly focused on improving throughput and fidelity via entanglement routing or single-node scheduling. This…

Networking and Internet Architecture · Computer Science 2023-03-31 Huayue Gu , Ruozhou Yu , Zhouyu Li , Xiaojian Wang , Fangtong Zhou

We study entanglement percolation in qubit-based planar quantum network models of arbitrary topology, where neighboring nodes are initially connected by pure states with quenched disorder in their entanglement. To address this, we develop a…

Quantum Physics · Physics 2025-06-27 Andrea De Girolamo , Giuseppe Magnifico , Cosmo Lupo

Entanglement-based quantum networks exhibit a unique flexibility in the choice of entangled resource states that are then locally manipulated by the nodes to fulfill any request in the network. Furthermore, this manipulation is not uniquely…

Quantum Physics · Physics 2025-02-04 Maria Flors Mor-Ruiz , Julius Wallnöfer , Wolfgang Dür

Output entanglement is a key element in quantum information processing. Here, we show how to obtain optimal entanglement between two filtered output fields in a three-mode optomechanical system. First, we obtain the key analytical…

Quantum Physics · Physics 2019-08-14 Xiao-Bo Yan , Zhi-Jiao Deng , Xue-Dong Tian , Jin-Hui Wu

Scalable quantum technologies will present challenges for characterizing and tuning quantum devices. This is a time-consuming activity, and as the size of quantum systems increases, this task will become intractable without the aid of…

In this paper, we propose a unified approach to harness quantum conformal methods for multi-output distributions, with a particular emphasis on two experimental paradigms: (i) a standard 2-qubit circuit scenario producing a four-dimensional…

Quantum Physics · Physics 2025-01-22 Emre Tasar

In this paper, we consider solving a composite optimization problem with coupling constraints in a multi-agent network based on proximal gradient method. In this problem, all the agents jointly minimize the sum of individual cost functions…

Optimization and Control · Mathematics 2021-08-30 Jianzheng Wang , Guoqiang Hu

Two-phase sampling is commonly adopted for reducing cost and improving estimation efficiency. In many two-phase studies, the outcome and some cheap covariates are observed for a large sample in Phase I, and expensive covariates are obtained…

Methodology · Statistics 2025-10-14 Qingning Zhou , Kin Yau Wong