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The physics of a closed quantum mechanical system is governed by its Hamiltonian. However, in most practical situations, this Hamiltonian is not precisely known, and ultimately all there is are data obtained from measurements on the system.…

Neural networks for image classification tasks assume that any given image during inference belongs to one of the training classes. This closed-set assumption is challenged in real-world applications where models may encounter inputs of…

Computer Vision and Pattern Recognition · Computer Science 2022-06-17 Jinsol Lee , Ghassan AlRegib

This paper investigates system identification problems with Gaussian inputs and quantized observations under fixed thresholds. By reinterpreting the nonlinear effects induced by quantization as the product of the unknown parameter and an…

Optimization and Control · Mathematics 2025-10-20 Xingrui Liu , Ying Wang , Yanlong Zhao

We present a gradient-based identification algorithm to identify the system matrices of a linear port-Hamiltonian system from given input-output time data. Aiming for a direct structure-preserving approach, we employ techniques from optimal…

Optimization and Control · Mathematics 2023-12-22 Michael Günther , Birgit Jacob , Claudia Totzeck

Hybrid quantum-classical optimization algorithms represent one of the most promising application for near-term quantum computers. In these algorithms the goal is to optimize an observable quantity with respect to some classical parameters,…

Quantum Physics · Physics 2021-01-27 Leonardo Banchi , Gavin E. Crooks

Many optimization methods for training variational quantum algorithms are based on estimating gradients of the cost function. Due to the statistical nature of quantum measurements, this estimation requires many circuit evaluations, which is…

Quantum Physics · Physics 2022-10-14 Lennart Bittel , Jens Watty , Martin Kliesch

In open quantum systems, phenomenological master equations with unknown parameters are often introduced. Here we propose a time-independent procedure based on quantum tomography to reconstruct the potentially unknown parameters of a wide…

Quantum Physics · Physics 2010-02-21 Bruno Bellomo , Antonella De Pasquale , Giulia Gualdi , Ugo Marzolino

Quantum process characterization is a fundamental task in quantum information processing, yet conventional methods, such as quantum process tomography, require prohibitive resources and lack scalability. Here, we introduce an efficient…

Quantum Physics · Physics 2025-04-11 Yusen Wu , Yukun Zhang , Chuan Wang , Xiao Yuan

This paper gives an overview of parameter estimation and system identification for quantum input-output systems by continuous observation of the output field. We present recent results on the quantum Fisher information of the output with…

Quantum Physics · Physics 2022-05-25 Hendra I. Nurdin , Madalin Guţǎ

Characterizing nonequilibrium dynamics in quantum many-body systems is a challenging frontier of physics. In this Letter, we systematically construct solvable nonintegrable quantum circuits that exhibit exact hidden Markovian subsystem…

Quantum Physics · Physics 2024-11-22 He-Ran Wang , Xiao-Yang Yang , Zhong Wang

Estimating extensive combinations of local parameters in distributed quantum systems is a central problem in quantum sensing, with applications ranging from magnetometry to timekeeping. While optimal strategies are known for sensing…

One of the most important topics in the study of the dynamics of open quantum system is information exchange between system and environment. Based on the features of a back-flow information from an environment to a system, an approach is…

Quantum Physics · Physics 2015-09-23 S. Haseli , S. Salimi , A. S. Khorashad

Open quantum systems are a rich area of research in the intersection of quantum mechanics and stochastic analysis. By considering a variety of master equations, we unify multiple views of autonomous and controlled open quantum systems and,…

Quantum Physics · Physics 2025-10-28 Waqas Parvaiz , Johannes Aspman , Ales Wodecki , Georgios Korpas , Jakub Marecek

The study of open quantum systems is important for fundamental issues of quantum physics as well as for technological applications such as quantum information processing. The interaction of a quantum system with it's environment is usually…

Quantum Physics · Physics 2016-02-02 Jun Sun , Yong-Nan Sun , Chuan-Feng Li , Guang-Can Guo , Kimmo Luoma , Jyrki Piilo

Predicting observables in equilibrium states is a central yet notoriously hard question in quantum many-body systems. In the physically relevant thermodynamic limit, certain mathematical formulations of this task have even been shown to…

Quantum Physics · Physics 2025-08-15 Hamza Fawzi , Omar Fawzi , Samuel O. Scalet

Researchers develop models to explain the unknowns. These models typically involve parameters that capture tangible quantities, the estimation of which is desired. Parameter identifiability investigates the recoverability of the unknown…

Optimization and Control · Mathematics 2024-07-01 Anuththara Sarathchandra , Azadeh Aghaeeyan , Pouria Ramazi

We present a numerical approach for approximating unknown Hamiltonian systems using observation data. A distinct feature of the proposed method is that it is structure-preserving, in the sense that it enforces conservation of the…

Numerical Analysis · Mathematics 2021-07-13 Kailiang Wu , Tong Qin , Dongbin Xiu

We present a distributed optimization algorithm for solving online personalized optimization problems over a network of computing and communicating nodes, each of which linked to a specific user. The local objective functions are assumed to…

Systems and Control · Electrical Eng. & Systems 2021-04-15 Ivano Notarnicola , Andrea Simonetto , Francesco Farina , Giuseppe Notarstefano

Accurate identification of Hamiltonian parameters is essential for modeling and controlling open quantum systems. In this work, we demonstrate that the multichannel Hankel alternative view of Koopman (mHAVOK) algorithm is a robust and…

Quantum Physics · Physics 2026-04-24 Jorge E. Pérez-García , Carlos Colchero , Julio C. Gutiérrez-Vega

We present a data-driven numerical approach for modeling unknown dynamical systems with missing/hidden parameters. The method is based on training a deep neural network (DNN) model for the unknown system using its trajectory data. A key…

Machine Learning · Statistics 2022-02-07 Xiaohan Fu , Weize Mao , Lo-Bin Chang , Dongbin Xiu