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Quantum computers promise to enhance machine learning for practical applications. Quantum machine learning for real-world data has to handle extensive amounts of high-dimensional data. However, conventional methods for measuring quantum…

Quantum Physics · Physics 2023-02-10 Tobias Haug , Chris N. Self , M. S. Kim

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 present a detailed account of quantum state estimation by joint maximization of the likelihood and the entropy. After establishing the algorithms for both perfect and imperfect measurements, we apply the procedure to data from simulated…

We present a variational algorithm for fault tolerant quantum computing to solve a system of linear equations which directly maximises the parameters of the target fidelity. This so-called measurement test algorithm can be applied to any…

Quantum Physics · Physics 2026-04-30 Alain Giresse Tene , Thomas Konrad

We introduce the concept of quantum minimal learning machine (QMLM), a supervised similarity-based learning algorithm. The algorithm is conceptually based on a classical machine learning model and adopted to work with quantum data. We will…

Quantum Physics · Physics 2026-03-10 Clemens Lindner , Joonas Hämäläinen , Matti Raasakka

The problem of determining whether a given quantum state is entangled lies at the heart of quantum information processing, which is known to be an NP-hard problem in general. Despite the proposed many methods such as the positive partial…

Quantum Physics · Physics 2018-07-18 Sirui Lu , Shilin Huang , Keren Li , Jun Li , Jianxin Chen , Dawei Lu , Zhengfeng Ji , Yi Shen , Duanlu Zhou , Bei Zeng

High fidelity state preparation represents a fundamental challenge in the application of quantum technology. While the majority of optimal control approaches use feedback to improve the controller, the controller itself often does not…

Quantum Physics · Physics 2021-11-22 Ethan N. Evans , Ziyi Wang , Adam G. Frim , Michael R. DeWeese , Evangelos A. Theodorou

Quantum state tomography (QST) is plagued by the ``curse of dimensionality'' due to the exponentially-scaled complexity in measurement and data post-processing. Efficient QST schemes for large-scale mixed states are currently missing. In…

Quantum Physics · Physics 2023-08-15 Wen-jun Li , Kai Xu , Heng Fan , Shi-ju Ran , Gang Su

Characterization of quantum systems from experimental data is a central problem in quantum science and technology. But which measurements should be used to gather data in the first place? While optimal measurement choices can be worked out…

Quantum Physics · Physics 2025-07-15 Jiaxin Huang , Yan Zhu , Giulio Chiribella , Ya-Dong Wu

Quantum computing hardware has grown sufficiently complex that it often can no longer be simulated by classical computers, but its computational power remains limited by errors. These errors corrupt the results of quantum algorithms, and it…

We propose active steering protocols for quantum state preparation in quantum circuits where each system qubit is connected to a single detector qubit, employing a simple coupling selected from a small set of steering operators. The…

Quantum Physics · Physics 2024-03-07 Samuel Morales , Yuval Gefen , Igor Gornyi , Alex Zazunov , Reinhold Egger

Demonstrating a quantum computational advantage will require high-fidelity control and readout of multi-qubit systems. As system size increases, multiplexed qubit readout becomes a practical necessity to limit the growth of resource…

We propose an effective approach to rapid estimation of the energy spectrum of quantum systems with the use of machine learning (ML) algorithm. In the ML approach (back propagation), the wavefunction data known from experiments is…

Computational Physics · Physics 2020-01-29 Gennadiy Burlak

Reconstructing quantum states from measurement data represents a formidable challenge in quantum information science, especially as system sizes grow beyond the reach of traditional tomography methods. While recent studies have explored…

Quantum Physics · Physics 2026-04-06 Shabnam Jabeen , Dmytro Kurdydyk , Aadi Palnitkar , Mihir Talati , Jeffrey Yan , Jinghong Yang

The calibration of quantum measurements is limited by the ability to accurately prepare quantum states under unknown device errors. We develop an accurate calibration protocol for the measurement apparatus of a quantum computer that is…

It is shown that a good estimate of the fidelity of an experimentally realized quantum process can be obtained by measuring the outputs for only two complementary sets of input states. The number of measurements required to test a quantum…

Quantum Physics · Physics 2009-11-10 Holger F. Hofmann

Quantum fidelity is one of the most important measures of similarity between mixed quantum states. However, the usual formulation is cumbersome and hard to understand when encountering the first time. This work shows in a novel, elegant…

Quantum Physics · Physics 2023-10-11 Adrian Müller

Quantifying unknown quantum entanglement experimentally is a difficult task, but also becomes more and more necessary because of the fast development of quantum engineering. Machine learning provides practical solutions to this fundamental…

Quantum Physics · Physics 2023-06-21 Xiaodie Lin , Zhenyu Chen , Zhaohui Wei

Quantum technologies exploit entanglement to enhance various tasks beyond their classical limits including computation, communication and measurements. Quantum metrology aims to increase the precision of a measured quantity that is…

Quantum Physics · Physics 2020-08-25 Bálint Koczor , Suguru Endo , Tyson Jones , Yuichiro Matsuzaki , Simon C. Benjamin

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