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Efficient sampling from ensembles of Hamiltonian cycles is critical for predicting the thermodynamic properties of compact polymers, with applications including modeling protein and RNA folding and designing soft materials. Although…

Quantum Physics · Physics 2026-03-16 Davide Rattacaso , Daniel Jaschke , Antonio Trovato , Ilaria Siloi , Simone Montangero

In order to leverage the full power of quantum noise squeezing with unavoidable decoherence, a complete understanding of the degradation in the purity of squeezed light is demanded. By implementing machine learning architecture with a…

Quantum state tomography, which aims to find the best description of a quantum state -- the density matrix, is an essential building block in quantum computation and communication. Standard techniques for state tomography are incapable of…

Quantum Physics · Physics 2022-11-18 Markus Rambach , Akram Youssry , Marco Tomamichel , Jacquiline Romero

Time series are often complex and rich in information but sparsely labeled and therefore challenging to model. In this paper, we propose a self-supervised framework for learning generalizable representations for non-stationary time series.…

Machine Learning · Computer Science 2021-06-03 Sana Tonekaboni , Danny Eytan , Anna Goldenberg

Estimating the eigenvalues of a unitary transformation U by standard phase estimation requires the implementation of controlled-U-gates which are not available if U is only given as a black box. We show that a simple trick allows to measure…

Quantum Physics · Physics 2007-05-23 Dominik Janzing , Thomas Beth

We provide an adaptive learning algorithm for tomography of general quantum states. Our proposal is based on the simultaneous perturbation stochastic approximation algorithm and is applicable on mixed qudit states. The salient features of…

Quantum Physics · Physics 2021-06-14 Ahmad Farooq , Muhammad Asad Ullah , Syahri Ramadhani , Junaid ur Rehman , Hyundong Shin

One of the key challenges in quantum machine learning is finding relevant machine learning tasks with a provable quantum advantage. A natural candidate for this is learning unknown Hamiltonian dynamics. Here, we tackle the supervised…

Quantum Physics · Physics 2025-06-23 Alice Barthe , Mahtab Yaghubi Rad , Michele Grossi , Vedran Dunjko

The goal of this work is to define a notion of a quantum neural network to classify data, which exploits the low energy spectrum of a local Hamiltonian. As a concrete application, we build a binary classifier, train it on some actual data…

Quantum Physics · Physics 2018-09-07 Johannes Bausch

An observer-based Hamiltonian identification algorithm for quantum systems is proposed. For the 2-level case an exponential convergence result based on averaging arguments and some relevant transformations is provided. The convergence for…

Mathematical Physics · Physics 2007-05-23 Mazyar Mirrahimi , Pierre Rouchon

Automated analyses of the outcome of a simulation have been an important part of atomistic modeling since the early days, addressing the need of linking the behavior of individual atoms and the collective properties that are usually the…

Chemical Physics · Physics 2019-05-22 Michele Ceriotti

Modern laboratory techniques like ultrafast laser excitation and shock compression can bring matter into highly nonequilibrium states with complex structural transformation, metallization and dissociation dynamics. To understand and model…

Computational Physics · Physics 2022-05-24 Qiyu Zeng , Bo Chen , Xiaoxiang Yu , Shen Zhang , Dongdong Kang , Han Wang , Jiayu Dai

Machine learning is widely believed to be one of the most promising practical applications of quantum computing. Existing quantum machine learning schemes typically employ a quantum-classical hybrid approach that relies crucially on…

Quantum Physics · Physics 2025-02-11 Qi Ye , Shuangyue Geng , Zizhao Han , Weikang Li , L. -M. Duan , Dong-Ling Deng

We make the case for studying the complexity of approximately simulating (sampling) quantum systems for reasons beyond that of quantum computational supremacy, such as diagnosing phase transitions. We consider the sampling complexity as a…

Quantum Physics · Physics 2018-08-07 Abhinav Deshpande , Bill Fefferman , Minh C. Tran , Michael Foss-Feig , Alexey V. Gorshkov

We introduce the problem of unsupervised classification of quantum data, namely, of systems whose quantum states are unknown. We derive the optimal single-shot protocol for the binary case, where the states in a disordered input array are…

Quantum Physics · Physics 2019-11-11 Gael Sentís , Alex Monràs , Ramon Muñoz-Tapia , John Calsamiglia , Emilio Bagan

Understanding complex quantum dynamics in realistic materials requires insight into the underlying correlations dominating the interactions between the participating particles. Due to the wealth of information involved in these processes,…

Materials Science · Physics 2024-04-19 Adva Baratz , Galit Cohen , Sivan Refaely-Abramson

We introduce a new method to reconstruct unknown quantum states out of incomplete and noisy information. The method is a linear convex optimization problem, therefore with a unique minimum, which can be efficiently solved with Semidefinite…

Quantum Physics · Physics 2011-12-01 Thiago O. Maciel , André T. Cesário , Reinaldo O. Vianna

Reliable methods for the classification and quantification of quantum entanglement are fundamental to understanding its exploitation in quantum technologies. One such method, known as Separable Neural Network Quantum States (SNNS), employs…

Quantum Physics · Physics 2021-06-15 Cillian Harney , Mauro Paternostro , Stefano Pirandola

In quantum many-body systems, characterizing topological phase transitions typically requires complex many-body topological invariants, which are costly to compute and measure. Inspired by quantum reservoir computing, we propose an…

Quantum Physics · Physics 2026-01-21 Li Xin , Da Zhang , Zhang-Qi Yin

Quantum state tomography, a process that reconstructs a quantum state from measurements on an ensemble of identically prepared copies, plays a crucial role in benchmarking quantum devices. However, brute-force approaches to quantum state…

Given a multiparticle quantum state, one may ask whether it can be represented as a thermal state of some Hamiltonian with k-particle interactions only. The distance from the exponential family defined by these thermal states can be…

Quantum Physics · Physics 2013-03-08 Sönke Niekamp , Tobias Galla , Matthias Kleinmann , Otfried Gühne