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Quantum State Tomography (QST) is a fundamental technique in Quantum Information Processing (QIP) for reconstructing unknown quantum states. However, the conventional QST methods are limited by the number of measurements required, which…

Quantum state tomography (QST) aims at estimating a quantum state from averaged quantum measurements made on copies of the state. Most quantum algorithms rely on QST at some point and it is a well explored topic in the literature, mostly…

Quantum Physics · Physics 2023-01-18 François Verdeil , Yannick Deville

The experimental realization of increasingly complex synthetic quantum systems calls for the development of general theoretical methods, to validate and fully exploit quantum resources. Quantum-state tomography (QST) aims at reconstructing…

Disordered Systems and Neural Networks · Physics 2018-05-17 Giacomo Torlai , Guglielmo Mazzola , Juan Carrasquilla , Matthias Troyer , Roger Melko , Giuseppe Carleo

As we enter a new era of quantum technology, it is increasingly important to develop methods to aid in the accurate preparation of quantum states for a variety of materials, matter, and devices. Computational techniques can be used to…

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

We consider the hypothetical quantum network case where Alice wishes to transmit one qubit of information (specifically a pure quantum state) to $M$ parties, where $M$ is some large number. The remote receivers locally perform single qubit…

Quantum Physics · Physics 2025-09-16 Elijah Pelofske

Quantum tomography is an essential method of the photonic technology toolbox and is routinely used for evaluation of experimentally prepared states of light and characterization of devices transforming such states. The tomography procedure…

Quantum Physics · Physics 2018-12-18 Radim Hošák , Robert Stárek , Miroslav Ježek

We propose a quantum tomography scheme for pure qudit systems which adopts random base measurements and generative learning methods, along with a built-in fidelity estimation approach to assess the reliability of the tomographic states. We…

Quantum Physics · Physics 2020-03-25 Jun Wang , Zhao-Yu Han , Song-Bo Wang , Zeyang Li , Liang-Zhu Mu , Heng Fan , Lei Wang

We introduce a new decomposition of the multiqubit states of the form $\rho^{\otimes N}$ and employ it to construct the optimal single qubit purification procedure. The same decomposition allows us to study optimal quantum cloning and state…

Quantum Physics · Physics 2009-10-31 J. I. Cirac , A. K. Ekert , C. Macchiavello

We consider a problem we call StateIsomorphism: given two quantum states of n qubits, can one be obtained from the other by rearranging the qubit subsystems? Our main goal is to study the complexity of this problem, which is a natural…

Quantum Physics · Physics 2017-09-28 Joshua Lockhart , Carlos E. González Guillén

Well-controlled quantum devices with their increasing system size face a new roadblock hindering further development of quantum technologies: The effort of quantum tomography---the characterization of processes and states within a quantum…

Quantum Physics · Physics 2017-05-26 C. A. Riofrio , D. Gross , S. T. Flammia , T. Monz , D. Nigg , R. Blatt , J. Eisert

Quantum state tomography is a powerful, but resource-intensive, general solution for numerous quantum information processing tasks. This motivates the design of robust tomography procedures that use relevant resources as sparingly as…

Quantum Physics · Physics 2022-01-17 Fernando G. S. L. Brandão , Richard Kueng , Daniel Stilck França

We consider the following task: suppose an algorithm is given copies of an unknown $n$-qubit quantum state $|\psi\rangle$ promised $(i)$ $|\psi\rangle$ is $\varepsilon_1$-close to a stabilizer state in fidelity or $(ii)$ $|\psi\rangle$ is…

Quantum Physics · Physics 2024-11-13 Srinivasan Arunachalam , Arkopal Dutt

We give a polynomial time algorithm that, given copies of an unknown quantum state $\vert\psi\rangle=U\vert 0^n\rangle$ that is prepared by an unknown constant depth circuit $U$ on a finite-dimensional lattice, learns a constant depth…

Quantum Physics · Physics 2025-06-18 Zeph Landau , Yunchao Liu

We discuss the usefulness of quantum cloning and present examples of quantum computation tasks for which cloning offers an advantage which cannot be matched by any approach that does not resort to it. In these quantum computations, we need…

Quantum Physics · Physics 2007-05-23 Gao Ting , Yan Feng-Li , Wang Zhi-Xi

Rapid improvement in quantum hardware has opened the door to complex problems, but the precise characterization of quantum systems itself remains a challenge. To address this obstacle, novel tomography schemes have been developed that…

Quantum Physics · Physics 2022-07-08 Abigail McClain Gomez , Susanne F. Yelin , Khadijeh Najafi

Quantum theory has the property of "local tomography": the state of any composite system can be reconstructed from the statistics of measurements on the individual components. In this respect the holism of quantum theory is limited. We…

Quantum Physics · Physics 2015-05-19 Lucien Hardy , William K. Wootters

Probabilistically creating n perfect clones from m copies for one of N priori known quantum states with minimum failure probability is a long-standing problem. We provide a rigorous proof for the geometric approach to this probabilistic…

Quantum Physics · Physics 2019-05-07 Haixin Liu , Heng Fan

Quantum states obey an asymptotic no-cloning theorem, stating that no deterministic machine can reliably replicate generic sequences of identically prepared pure states. In stark contrast, we show that generic sequences of unitary gates can…

Quantum Physics · Physics 2015-04-01 G. Chiribella , Y. Yang , C. Huang

Given a finite number of copies of an unknown qubit state that have already been measured optimally, can one still extract any information about the original unknown state? We give a positive answer to this question and quantify the…

Quantum Physics · Physics 2015-05-13 Peter Rapcan , John Calsamiglia , Ramon Munoz-Tapia , Emilio Bagan , Vladimir Buzek