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The quantum density matrix generalises the classical concept of probability distribution to quantum theory. It gives the complete description of a quantum state as well as the observable quantities that can be extracted from it. Its…

Quantum Physics · Physics 2023-08-31 Apoorva D. Patel

Quantum state reconstruction using Neural Quantum States has been proposed as a viable tool to reduce quantum shot complexity in practical applications, and its advantage over competing techniques has been shown in numerical experiments…

Quantum Physics · Physics 2024-05-29 Haimeng Zhao , Giuseppe Carleo , Filippo Vicentini

We consider an inverse scattering problem for time-harmonic acoustic or electromagnetic waves. The goal is to localize several small penetrable objects embedded inside an otherwise homogeneous background medium from observations of far…

Numerical Analysis · Mathematics 2017-04-05 Roland Griesmaier , Christian Schmiedecke

We present a new procedure for quantum state reconstruction based on weak continuous measurement of an ensemble average. By applying controlled evolution to the initial state new information is continually mapped onto the measured…

Quantum Physics · Physics 2009-11-10 Andrew Silberfarb , Poul S. Jessen , Ivan H. Deutsch

The total least squares~(TLS) method is widely used in data-fitting. Compared with the least squares fitting method, the TLS fitting takes into account not only observation errors, but also errors from the measurement matrix of the…

Quantum Physics · Physics 2019-06-05 Hefeng Wang , Hua Xiang

Most existing learning-based methods for solving imaging inverse problems can be roughly divided into two classes: iterative algorithms, such as plug-and-play and diffusion methods leveraging pretrained denoisers, and unrolled architectures…

Image and Video Processing · Electrical Eng. & Systems 2026-03-31 Matthieu Terris , Samuel Hurault , Maxime Song , Julian Tachella

Quantum computation has been growing rapidly in both theory and experiments. In particular, quantum computing devices with a large number of qubits have been developed by IBM, Google, IonQ, and others. The current quantum computing devices…

Quantum Physics · Physics 2021-02-10 Rishabh Gupta , Rongxin Xia , Raphael D. Levine , Sabre Kais

We reconstruct a matrix product state (MPS) in reduced spaces using density matrix. This scheme applies to a MPS built on a blocked quantum lattice. Each block contains $N$ physical sites that have a local space of rank $R$. The simulation…

Strongly Correlated Electrons · Physics 2018-09-17 Lihua Wang , Kwang S. Kim

We show how group symmetries can be used to reconstruct quantum states. In our scheme for SU(1,1) states, the input field passes through a non-degenerate parametric amplifier and one measures the probability of finding the output state with…

Quantum Physics · Physics 2009-11-06 G. S. Agarwal , J. Banerji

We introduce an analytical iterative method, the density matrix recursion method, to generate arbitrary reduced density matrices of superpositions of short-range dimer coverings on periodic or non-periodic quantum spin-1/2 ladder lattices,…

Quantum Physics · Physics 2013-01-22 Himadri Shekhar Dhar , Aditi Sen De , Ujjwal Sen

An architecture for hardware realization of a system for sparse signal reconstruction is presented. The threshold based reconstruction method is considered, which is further modified in this paper to reduce the system complexity in order to…

Information Theory · Computer Science 2016-11-29 Irena Orovic , Andjela Draganic , Nedjeljko Lekic , Srdjan Stankovic

We show how the rotational quantum state of a linear or symmetric top rotor can be reconstructed from finite time observations of the polar angular distribution under certain conditions. The presented tomographic method can reconstruct the…

Quantum Physics · Physics 2009-11-11 Anders S. Mouritzen , Klaus Molmer

We consider the inverse problem of reconstructing inhomogeneities by performing a finite number of scattering measurements of acoustic type in the time-harmonic setting. We set up the reconstruction as a fully discrete variational problem…

Analysis of PDEs · Mathematics 2026-02-24 Daniela Di Donato , Luca Rondi

We implement a compressive quantum state tomography capable of reconstructing any arbitrary low-rank spectral-temporal optical signal with extremely few measurement settings and without any \emph{ad hoc} assumptions about the initially…

Quantum Physics · Physics 2021-05-27 J. Gil-Lopez , Y. S. Teo , S. De , B. Brecht , H. Jeong , C. Silberhorn , L. L. Sanchez-Soto

A real-time image reconstruction method for scanning transmission electron microscopy (STEM) is proposed. With an algorithm requiring only the center of mass (COM) of the diffraction pattern at one probe position at a time, it is able to…

Materials Science · Physics 2021-12-15 Chu-Ping Yu , Thomas Friedrich , Daen Jannis , Sandra Van Aert , Johan Verbeeck

Characterizing noisy quantum devices requires methods for learning the underlying quantum Hamiltonian which governs their dynamics. Often, such methods compare measurements to simulations of candidate Hamiltonians, a task which requires…

Quantum Physics · Physics 2021-10-13 Assaf Zubida , Elad Yitzhaki , Netanel H. Lindner , Eyal Bairey

Studying mechanical resonators via radiation pressure offers a rich avenue for the exploration of quantum mechanical behavior in a macroscopic regime. However, quantum state preparation and especially quantum state reconstruction of…

Quantum Physics · Physics 2011-10-12 M. R. Vanner , I. Pikovski , G. D. Cole , M. S. Kim , C. Brukner , K. Hammerer , G. J. Milburn , M. Aspelmeyer

We consider the method of infinite matrix inversion in the context of quantum state reconstruction. Using this method we give rigorous proofs for reconstruction formulas for the Cahill-Glauber s-parametrized distributions and the rotated…

Quantum Physics · Physics 2010-10-19 Jukka Kiukas , Juha-Pekka Pellonpää , Jussi Schultz

We consider the inverse problem of reconstructing an effective model for a prototypical diffusion process in strongly heterogeneous media based on coarse measurements. The approach is motivated by quasi-local numerical effective forward…

Numerical Analysis · Mathematics 2020-05-05 Alfonso Caiazzo , Roland Maier , Daniel Peterseim

Compressed sensing is triggering a major evolution in signal acquisition. It consists in sampling a sparse signal at low rate and later using computational power for its exact reconstruction, so that only the necessary information is…

Statistical Mechanics · Physics 2012-06-07 Florent Krzakala , Marc Mézard , François Sausset , Yifan Sun , Lenka Zdeborová