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Maximum likelihood iteration is one of the most commonly used reconstruction algorithms in quantum tomography. The main appeal of the method is that it is easy to implement and that it converges reliably to a physically meaningful density…

Quantum Physics · Physics 2025-08-21 Florian Oberender

X-ray spectral fitting of astronomical sources requires convolving the intrinsic spectrum or model with the instrumental response. Standard forward modeling techniques have proven success in recovering the underlying physical parameters in…

Instrumentation and Methods for Astrophysics · Physics 2021-05-21 Carter Lee Rhea , Julie Hlavacek-Larrondo , Ralph Kraft , Akos Bogdan , Rudy Geelen

Landauer-B\"uttiker formula describes the electronic quantum transports in nanostructures and molecules. It will be numerically demanding for simulations of complex or large size systems due to, for example, matrix inversion calculations.…

Mesoscale and Nanoscale Physics · Physics 2020-07-22 Yan Yu , Yan-Yang Zhang , Lei Liu , Si-Si Wang , Ji-Huan Guan , Yang Xia , Shu-Shen Li

Accurately establishing the state of large-scale quantum systems is an important tool in quantum information science; however, the large number of unknown parameters hinders the rapid characterisation of such states, and reconstruction…

Quantum Physics · Physics 2014-07-30 Francesco Tonolini , Susan Chan , Megan Agnew , Alan Lindsay , Jonathan Leach

Reversing unitary operations is a key task in quantum computing and quantum control. In this work, we introduce and develop the framework of shadow unitary inversion, a relaxed variant of unitary inversion in which the goal is to reproduce…

Quantum Physics · Physics 2026-05-29 Guocheng Zhen , Yu-Ao Chen , Mingrui Jing , Jingu Xie , Ranyiliu Chen , Xin Wang

We present quantum algorithms for the estimation of n-time correlation functions, the local and non-local density of states, and dynamical linear response functions. These algorithms are all based on block-encodings - a versatile technique…

Quantum Physics · Physics 2020-08-19 Patrick Rall

We demonstrate quantum many-body state reconstruction from experimental data generated by a programmable quantum simulator, by means of a neural network model incorporating known experimental errors. Specifically, we extract restricted…

In this paper, an efficient method is presented for solving three dimensional Volterra integral equations of the second kind with continuous kernel. Shifted Chebyshev polynomial is applied to approximate a solution for these integral…

Numerical Analysis · Mathematics 2016-09-28 Doaa shokry Mohamed

Quantum information processing has been effectively demonstrated on a small number of qubits by nuclear magnetic resonance. An important subroutine in any computing is the readout of the output. ``Spectral implementation'' originally…

Quantum Physics · Physics 2009-11-11 Ranabir Das , Anil Kumar

Modeling of the collimator-detector response (CDR) in SPECT reconstruction enables improved resolution and accuracy, and is thus important for quantitative imaging applications such as dosimetry. The implementation of CDR modeling, however,…

Modern technology for producing extremely bright and coherent X-ray laser pulses provides the possibility to acquire a large number of diffraction patterns from individual biological nanoparticles, including proteins, viruses, and DNA.…

Methodology · Statistics 2018-07-11 Stefan Engblom , Carl Nettelblad , Jing Liu

This work presents an efficient numerical method to evaluate the free energy density and associated thermodynamic quantities of (quasi) one-dimensional classical systems, by combining the transfer operator approach with a numerical…

Numerical Analysis · Mathematics 2021-03-09 Christian B. Mendl , Folkmar Bornemann

We address the inverse problem of cosmic large-scale structure reconstruction from a Bayesian perspective. For a linear data model, a number of known and novel reconstruction schemes, which differ in terms of the underlying signal prior,…

Astrophysics · Physics 2009-11-06 F. S. Kitaura , T. A. Ensslin

Frequency-dependent correlations, such as the spectral function and the dynamical structure factor, help understand condensed matter experiments. Within the density matrix renormalization group (DMRG) framework, an accurate method for…

Strongly Correlated Electrons · Physics 2016-12-21 A. Nocera , G. Alvarez

The multichannel generalization of the theory of spectral, scattering and decay control is presented. New universal algorithms of construction of complex quantum systems with given properties are suggested. Particularly, transformations of…

Quantum Physics · Physics 2009-11-07 V. M. Chabanov , B. N. Zakhariev , I. V. Amirkhanov

New techniques based on weak measurements have recently been introduced to the field of quantum state reconstruction. Some of them allow the direct measurement of each matrix element of an unknown density operator and need only $O(d)$…

Quantum Physics · Physics 2019-01-31 Luca Calderaro , Giulio Foletto , Daniele Dequal , Paolo Villoresi , Giuseppe Vallone

Based on the Kompaneets approximation, we develop a robust methodology to calculate spectral redistribution via inelastic neutrino-nucleon scattering in the context of core-collapse supernova simulations. The resulting equations conserve…

High Energy Astrophysical Phenomena · Physics 2021-08-26 Tianshu Wang , Adam Burrows

Feasible tomography schemes for large particle numbers must possess, besides an appropriate data acquisition protocol, also an efficient way to reconstruct the density operator from the observed finite data set. Since state reconstruction…

We propose a spectral method based on the implementation of Chebyshev polynomials to study a model of conservation laws on network. We avoid the Gibbs phenomenon near shock discontinuities by implementing a filter in the frequency space in…

Numerical Analysis · Mathematics 2023-05-26 Sabrina Francesca Pellegrino

The number of measurements required to reconstruct the states of quantum systems increases exponentially with the quantum system dimensions, which makes the state reconstruction of high-qubit quantum systems have a great challenge in…

Quantum Physics · Physics 2017-11-08 J. Yang , S. Cong , X. Liu , Z. Li , K. Li
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