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We propose an efficient protocol to estimate the fidelity of an $n$-qubit entangled measurement device, requiring only qubit state preparations and classical data post-processing. It works by measuring the eigenstates of Pauli operators,…

Quantum Physics · Physics 2023-12-22 Zanqiu Shen , Kun Wang

We propose a measurement scheme that validates the preparation of an $n$-qubit stabilizer state. The scheme involves a measurement of $n$ Pauli observables, a priori determined from the stabilizer state and which can be realized using…

Quantum Physics · Physics 2019-09-17 Amir Kalev , Anastasios Kyrillidis , Norbert M. Linke

Fidelity is the standard measure for quantifying the similarity between two quantum states. It is equal to the square of the minimum Bhattacharyya coefficient between the probability distributions induced by quantum measurements on the two…

Quantum Physics · Physics 2025-12-01 Datong Chen , Huangjun Zhu

Fidelity estimation for entangled states constitutes an essential building block for quality control and error detection in quantum networks. Nonetheless, quantum networks often encounter heterogeneous and correlated noise, leading to…

Quantum Physics · Physics 2024-11-18 Liangzhong Ruan , Bas Dirkse

One of the many interesting features of quantum nonlocality is that the states of a multipartite quantum system cannot always be distinguished as well by local measurements as they can when all quantum measurements are allowed. In this…

Quantum Physics · Physics 2013-11-14 Somshubhro Bandyopadhyay , Michael Nathanson

The fidelity and local unitary transformation are two widely useful notions in quantum physics. We study two constrained optimization problems in terms of the maximal and minimal fidelity between two bipartite quantum states undergoing…

Quantum Physics · Physics 2015-11-23 Lin Zhang , Lin Chen , Kaifeng Bu

In almost all quantum applications, one of the key steps is to verify that the fidelity of the prepared quantum state meets expectations. In this Letter, we propose a new approach solving this problem using machine-learning techniques.…

Quantum Physics · Physics 2021-09-28 Xiaoqian Zhang , Maolin Luo , Zhaodi Wen , Qin Feng , Shengshi Pang , Weiqi Luo , Xiaoqi Zhou

Fidelity estimation is essential for the quality control of entanglement distribution networks. Because measurements collapse quantum states, we consider a setup in which nodes randomly sample a subset of the entangled qubit pairs to…

Quantum Physics · Physics 2022-10-10 Liangzhong Ruan

We propose practical and efficient protocols for verifying bipartite pure states for any finite dimension, which can also be applied to fidelity estimation. Our protocols are based on adaptive local projective measurements with either…

Quantum Physics · Physics 2019-09-18 Zihao Li , Yun-Guang Han , Huangjun Zhu

We investigate the problem of bounding the quantum process fidelity given bounds on the fidelities between target states and the action of a process on a set of pure input states. We formulate the problem as a semidefinite program and prove…

Quantum Physics · Physics 2018-11-28 Karl Mayer , Emanuel Knill

Verifying the proper preparation of quantum states is essential in modern quantum information science. Various protocols have been developed to estimate the fidelity of quantum states produced by different parties. Direct fidelity…

Quantum Physics · Physics 2024-12-11 Christopher Vairogs , Bin Yan

A promising use of quantum computers is to prepare quantum states that model complex domains, such as correlated electron wavefunctions or the underlying distribution of a complex dataset. Such states need to be verified in view of…

Quantum Physics · Physics 2020-12-16 Ryan S. Bennink

We measure complete and continuous Wigner functions of a two-level cesium atom in both a nearly pure state and highly mixed states. We apply the method [T. Tilma et al., Phys. Rev. Lett. 117, 180401 (2016)] of strictly constructing…

Quantum Physics · Physics 2018-01-26 Yali Tian , Zhihui Wang , Pengfei Zhang , Gang Li , Jie Li , Tiancai Zhang

We estimate the quantum state of a light beam from results of quantum homodyne measurements performed on identically prepared quantum systems. The state is represented through the Wigner function, a generalized probability density on…

Statistics Theory · Mathematics 2011-06-23 Cristina Butucea , Madalin Guţa , Luis Artiles

Estimating the fidelity of state preparation in multi-qubit systems is generally a time-consuming task. Nevertheless, this complexity can be reduced if the desired state can be characterized by certain symmetries measurable with the…

Quantum Physics · Physics 2009-11-13 R. D. Somma , J. Chiaverini , D. J. Berkeland

We introduce a simulation-free method to estimate the fidelity of large quantum circuits based on the order statistics of measured output probabilities from highly entangled, chaotic states. The approach requires only the…

Quantum Physics · Physics 2025-10-16 Tobias Micklitz

Assessing the quality of an ensemble of noisy entangled states is a central task in quantum information processing. Usually this is done by measuring and hence destroying multiple copies, from which state tomography or fidelity estimation…

Quantum Physics · Physics 2023-02-14 Ferran Riera-Sàbat , Jorge Miguel-Ramiro , Wolfgang Dür

We describe a simple method for certifying that an experimental device prepares a desired quantum state rho. Our method is applicable to any pure state rho, and it provides an estimate of the fidelity between rho and the actual (arbitrary)…

Quantum Physics · Physics 2011-06-09 Steven T. Flammia , Yi-Kai Liu

We estimate the quantum state of a light beam from results of quantum homodyne measurements performed on identically prepared pulses. The state is represented through the Wigner function, a ``quasi-probability density'' on $\mathbb{R}^{2}$…

Statistics Theory · Mathematics 2011-06-23 Madalin Guta , Luis Artiles

Given a finite number $N$ of copies of a qubit state we compute the maximum fidelity that can be attained using joint-measurement protocols for estimating its purity. We prove that in the asymptotic $N\to\infty$ limit, separable-measurement…

Quantum Physics · Physics 2009-11-11 E. Bagan , M. A. Ballester , R. Munoz-Tapia , O. Romero-Isart