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Adaptive measurements have recently been shown to significantly improve the performance of quantum state and process tomography. However, the existing methods either cannot be straightforwardly applied to high-dimensional systems or are…

Quantum Physics · Physics 2018-10-02 Gleb Struchalin , Egor Kovlakov , Stanislav Straupe , Sergei Kulik

Model-independent estimation of the properties of quantum states is a central challenge in quantum technologies, as experimental imperfections, drifts, and imprecise models of the actual quantum dynamics inevitably hinder accurate…

Estimating physical properties of quantum states from measurements is one of the most fundamental tasks in quantum science. In this work, we identify conditions on states under which it is possible to infer the expectation values of all…

Quantum Physics · Physics 2024-05-01 Cambyse Rouzé , Daniel Stilck França

Quantum information has been drawing a wealth of research in recent years, shedding light on questions at the heart of quantum mechanics, as well as advancing fields such as complexity theory, cryptography, key distribution, and chemistry.…

Quantum Physics · Physics 2017-04-25 Dikla Oren , Maor Mutzafi , Yonina C. Eldar , Mordechai Segev

We study sequential quantum changepoint detection in settings where the pre- and post-change regimes are specified through constraints on the expectation values of a finite set of observables. We consider an architecture with separate…

Quantum Physics · Physics 2026-02-13 Matteo Zecchin , Osvaldo Simeone , Aaditya Ramdas

Ptychography is an imaging technique in which a localized illumination scans overlapping regions of an object and generates a set of diffraction intensities used to computationally reconstruct its complex-valued transmission function. We…

Quantum Physics · Physics 2019-12-18 Mário Foganholi Fernandes , Leonardo Neves

We propose a quantum information based scheme to reduce the temperature of quantum many-body systems, and access regimes beyond the current capability of conventional cooling techniques. We show that collective measurements on multiple…

Quantum probes that enable enhanced exploration and characterization of complex systems are central to modern science, spanning applications from biology to astrophysics and chemical design. In large many-body quantum systems, interactions…

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

Simulating quantum dynamics is one of the most important applications of quantum computers. Traditional approaches for quantum simulation involve preparing the full evolved state of the system and then measuring some physical quantity.…

Quantum Physics · Physics 2025-02-24 Rolando D. Somma , Robbie King , Robin Kothari , Thomas O'Brien , Ryan Babbush

We compare the two main techniques used for estimating the state of a physical system from unknown measurements: standard detector tomography and data-pattern tomography. Adopting linear inversion as a fair benchmark, we show that the…

Quantum Physics · Physics 2017-08-02 L. Motka , M. Paur , J. Rehacek , Z. Hradil , L. L. Sanchez-Soto

We introduce a simple protocol for measuring properties of a gapped ground state with essentially no disturbance to the state. The required Hamiltonian evolution time scales inversely with the spectral gap and target precision (up to…

Quantum Physics · Physics 2025-12-12 Chi-Fang Chen , Robbie King

The quantum measurement procedure based on the Lorentz transformation formalism and weak perturbation of the system is considered. In the simple case of a single-qubit it turns out that one can perform 4-dimension pseudo-rotation along with…

Quantum Physics · Physics 2019-06-18 Yu. I. Bogdanova , N. A. Bogdanova , B. I. Bantysh , Yu. A. Kuznetsov

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

We study the physical implementation of an optimal tomographic reconstruction scheme for the case of determining the state of a multi-qubit system, where trapped ions are used for defining qubits. The protocol is based on the use of…

Quantum Physics · Physics 2009-11-13 A. B. Klimov , A. Fernández , C. Muñoz , C. Saavedra

In this work, we investigate the application of deep learning methods for computed tomography in the context of having a low-data regime. As motivation, we review some of the existing approaches and obtain quantitative results after…

Image and Video Processing · Electrical Eng. & Systems 2021-04-20 Daniel Otero Baguer , Johannes Leuschner , Maximilian Schmidt

We present an error analysis of various tomographic protocols based on the linear inversion for the reconstruction of an unknown two-qubit state. We solve the problem of finding a tomographic protocol which is the most robust against errors…

Quantum Physics · Physics 2014-12-23 Adam Miranowicz , Karol Bartkiewicz , Jan Perina , Masato Koashi , Nobuyuki Imoto , Franco Nori

Medical ultrasound is widely used technique for diagnosing internal organs. As common artifacts, shadows often appear in ultrasound images. Detecting such shadows is curious because they prevent accurate diagnosis. In this paper, we propose…

Image and Video Processing · Electrical Eng. & Systems 2019-08-08 Suguru Yasutomi , Tatsuya Arakaki , Ryuji Hamamoto

In standard optical tomographic methods, the off-diagonal elements of a density matrix $\rho$ are measured indirectly. Thus, the reconstruction of $\rho$, even if it is based on linear inversion, typically magnifies small errors in the…

Quantum Physics · Physics 2016-07-19 Karol Bartkiewicz , Antonín Černoch , Karel Lemr , Adam Miranowicz

The method of classical shadows heralds unprecedented opportunities for quantum estimation with limited measurements [H.-Y. Huang, R. Kueng, and J. Preskill, Nat. Phys. 16, 1050 (2020)]. Yet its relationship to established quantum…

Quantum Physics · Physics 2021-07-19 Joseph M. Lukens , Kody J. H. Law , Ryan S. Bennink