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In this article, we investigate the problem of state reconstruction of four-level quantum systems. A realistic scenario is considered with measurement results distorted by random unitary operators. Two frames which define injective…

Quantum Physics · Physics 2021-07-20 Artur Czerwinski

The article establishes a framework for dynamic generation of informationally complete POVMs in quantum state tomography. Assuming that the evolution of a quantum system is given by a dynamical map in the Kraus representation, one can…

Quantum Physics · Physics 2021-03-15 Artur Czerwinski

Quantum state tomography is a crucial technique for characterizing the state of a quantum system, which is essential for many applications in quantum technologies. In recent years, there has been growing interest in leveraging neural…

Quantum Physics · Physics 2026-05-21 Nhan Trong Luu , Tuyen Quang Nguyen , Duong Trung Luu , Thang Cong Truong

Tomographic reconstruction of the many-body quantum state of a scalable qubit system is of paramount importance in quantum computing technologies. However, conventional approaches which use tomographically orthogonal base measurements…

Quantum Physics · Physics 2024-10-31 Kangheun Kim , Jaewook Ahn

The characterization of the dynamics of quantum systems is a task of both fundamental and practical importance. A general class of methods which have been developed in quantum information theory to accomplish this task is known as quantum…

Quantum Physics · Physics 2007-07-03 M. Mohseni , D. A. Lidar

A direct measurement protocol allows reconstructing specific elements of the density matrix of a quantum state without using quantum state tomography. However, the direct measurement protocols to date are primarily based on weak or strong…

Quantum Physics · Physics 2021-10-13 Tianfeng Feng , Changliang Ren , Xiaoqi Zhou

Given the state of a quantum system, one can calculate the expectation value of any observable of the system. However, the inverse problem of determining the state by performing different measurements is not a trivial task. In various…

Quantum Physics · Physics 2012-10-26 Bahar Mehmani , Theo M. Nieuwenhuizen

Detection of entanglement through partial knowledge of the quantum state is a challenge to implement efficiently. Here we propose a separability criterion for detecting bipartite entanglement in arbitrary dimensional quantum states using…

Quantum Physics · Physics 2024-05-28 Shruti Aggarwal , Satyabrata Adhikari , A. S. Majumdar

Quantum state tomography is an essential component of modern quantum technology. In application to continuous-variable harmonic-oscilator systems, such as the electromagnetic field, existing tomography methods typically reconstruct the…

Quantum Physics · Physics 2023-01-09 Ekaterina Fedotova , Nikolai Kuznetsov , Egor Tiunov , A. E. Ulanov , A. I. Lvovsky

A major bottleneck in the quest for scalable many-body quantum technologies is the difficulty in benchmarking their preparations, which suffer from an exponential `curse of dimensionality' inherent to their quantum states. We present an…

Quantum Physics · Physics 2019-07-31 Juan Carrasquilla , Giacomo Torlai , Roger G. Melko , Leandro Aolita

Many quantum states arising in algorithms and physical systems occupy only a small, structured subset of the exponentially large Hilbert space, yet standard quantum state tomography fails to exploit this structure. We present an efficient…

Quantum Physics · Physics 2025-12-24 Chi-Kwong Li , Kevin Yipu Wu , Zherui Zhang

We report the creation of a wide range of quantum states with controllable degrees of entanglement and entropy using an optical two-qubit source based on spontaneous parametric downconversion. The states are characterised using measures of…

Quantum Physics · Physics 2009-11-07 A. G. White , D. F. V. James , W. J. Munro , P. G. Kwiat

Quantum state tomography (QST) scales exponentially in both measurement and computational cost, making full reconstruction impractical for multi-qubit systems. Existing approaches attempt to reduce this complexity, but do not explicitly…

Quantum Physics · Physics 2026-04-24 Ayush Chambyal , Brijesh , Rakesh Sharma

We report experimental implementation of various types of qubit channels using an individual trapped ion. We analyzed experimental data and we performed tomographic reconstruction of quantum channels based on these data. Specifically, we…

Quantum Physics · Physics 2009-04-07 Thilo Hannemann , Christof Wunderlich , Martin Plesch , Mario Ziman , Vladimir Buzek

We discuss a procedure of measurement followed by the reproduction of the quantum state of a three-level optical system - a frequency- and spatially degenerate two-photon field. The method of statistical estimation of the quantum state…

We propose a quantum optics experiment where a single two-mode Gaussian entangled state is used for realizing the paradigm of an amendable Gaussian channel recently presented in Phys. Rev. A, \textbf{87}, 062307 (2013). Depending on the…

Due to the interaction with the environment, a quantum state is subjected to decoherence which becomes one of the biggest problems for practical quantum computation. Amplitude damping is one of the most important decoherence processes.…

Quantum Physics · Physics 2016-08-03 Saeideh Shahrokh Esfahani , Zeyang Liao , M. Suhail Zubairy

We propose an approach to reconstruct any superconducting charge qubit state by using quantum state tomography. This procedure requires a series of measurements on a large enough number of identically prepared copies of the quantum system.…

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

Entanglement among a large number of qubits is a crucial resource for many quantum algorithms. Such many-body states have been efficiently generated by entangling a chain of itinerant photonic qubits in the optical or microwave domain.…

We explore the main processes involved in the evolution of general quantum systems by means of Diagrams of States, a novel method to graphically represent and analyze how quantum information is elaborated during computations performed by…

Quantum Physics · Physics 2009-12-02 Sara Felloni , Alberto Leporati , Giuliano Strini