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Learning quantum Hamiltonians with high precision is important for quantum physics and quantum information science. We propose a multi-stage neural network framework that significantly enhances Hamiltonian learning precision through…

Quantum Physics · Physics 2025-03-11 Zhengjie Kang , Hao Li , Shuo Wang , Jiaojiao Li , Yuanjie Zhang , Zhihuang Luo

Hamiltonian learning is crucial to the certification of quantum devices and quantum simulators. In this paper, we propose a hybrid quantum-classical Hamiltonian learning algorithm to find the coefficients of the Pauli operator components of…

Quantum Physics · Physics 2023-10-16 Youle Wang , Guangxi Li , Xin Wang

We present an efficient quantum algorithm for simulating the evolution of a sparse Hamiltonian H for a given time t in terms of a procedure for computing the matrix entries of H. In particular, when H acts on n qubits, has at most a…

Quantum Physics · Physics 2007-05-23 Dominic W. Berry , Graeme Ahokas , Richard Cleve , Barry C. Sanders

Hybrid quantum systems with different particle species are fundamental in quantum materials and quantum information science. In this work, we establish a rigorous theoretical framework proving that, given access to an unknown spin-boson…

Quantum Physics · Physics 2025-05-01 Lixing Zhang , Ze-Xun Lin , Prineha Narang , Di Luo

We study the problem of efficiently learning an unknown $n$-qubit unitary channel in diamond distance given query access. We present a general framework showing that if Pauli operators remain low-complexity under conjugation by a unitary,…

Quantum Physics · Physics 2026-04-07 Sabee Grewal , Daniel Liang

We provide a quantum algorithm for simulating the dynamics of sparse Hamiltonians with complexity sublogarithmic in the inverse error, an exponential improvement over previous methods. Specifically, we show that a $d$-sparse Hamiltonian $H$…

Quantum Physics · Physics 2014-10-09 Dominic W. Berry , Andrew M. Childs , Richard Cleve , Robin Kothari , Rolando D. Somma

We describe a slightly sub-exponential time algorithm for learning parity functions in the presence of random classification noise. This results in a polynomial-time algorithm for the case of parity functions that depend on only the first…

Machine Learning · Computer Science 2007-05-23 Avrim Blum , Adam Kalai , Hal Wasserman

Local Hamiltonians arise naturally in physical systems. Despite its seemingly `simple' local structure, exotic features such as nonlocal correlations and topological orders exhibit in eigenstates of these systems. Previous studies for…

Quantum Physics · Physics 2020-10-30 Shi-Yao Hou , Ningping Cao , Sirui Lu , Yi Shen , Yiu-Tung Poon , Bei Zeng

We present a quantum algorithm for simulating the dynamics of Hamiltonians that are not necessarily sparse. Our algorithm is based on the input model where the entries of the Hamiltonian are stored in a data structure in a quantum random…

Quantum Physics · Physics 2020-06-11 Chunhao Wang , Leonard Wossnig

Solving the ground state and the ground-state properties of quantum many-body systems is generically a hard task for classical algorithms. For a family of Hamiltonians defined on an $m$-dimensional space of physical parameters, the ground…

Quantum Physics · Physics 2024-08-13 Yanming Che , Clemens Gneiting , Franco Nori

Hamiltonian learning is a cornerstone for advancing accurate many-body simulations, improving quantum device performance, and enabling quantum-enhanced sensing. Existing readily deployable quantum metrology techniques primarily focus on…

Quantum Physics · Physics 2025-10-10 Suying Liu , Xiaodi Wu , Murphy Yuezhen Niu

Identifying unknown Hamiltonians from their quantum dynamics is a pivotal challenge in quantum technologies. In this paper, we introduce Hamiltonian recognition, a framework that bridges quantum hypothesis testing and quantum metrology,…

Quantum Physics · Physics 2026-02-26 Chengkai Zhu , Shuyu He , Yu-Ao Chen , Lei Zhang , Xin Wang

We introduce a generalizable framework for learning to identify effective Hamiltonians directly from experimental data in solid-state quantum systems. Our approach is based on a physics-informed neural network architecture that embeds…

Mesoscale and Nanoscale Physics · Physics 2026-03-04 Jarosław Pawłowski , Mateusz Krawczyk

We study the problem of learning the Hamiltonian of a quantum many-body system given samples from its Gibbs (thermal) state. The classical analog of this problem, known as learning graphical models or Boltzmann machines, is a well-studied…

Quantum Physics · Physics 2021-05-26 Anurag Anshu , Srinivasan Arunachalam , Tomotaka Kuwahara , Mehdi Soleimanifar

Hamiltonian Learning (HL) is essential for validating quantum systems in quantum computing. Not all Hamiltonians can be uniquely recovered from a steady state. HL success depends on the Hamiltonian model and steady state. Here, we analyze…

Quantum Physics · Physics 2023-09-19 Jing Zhou , D. L. Zhou

Recovering an unknown Hamiltonian from measurements is an increasingly important task for certification of noisy quantum devices and simulators. Recent works have succeeded in recovering the Hamiltonian of an isolated quantum system with…

Quantum Physics · Physics 2019-01-24 Eyal Bairey , Itai Arad , Netanel H. Lindner

Reconstructing a system Hamiltonian through measurements on its eigenstates is an important inverse problem in quantum physics. Recently, it was shown that generic many-body local Hamiltonians can be recovered by local measurements without…

Quantum Physics · Physics 2022-02-14 Chenfeng Cao , Shi-Yao Hou , Ningping Cao , Bei Zeng

We develop a protocol for learning a class of interacting bosonic Hamiltonians from dynamics with Heisenberg-limited scaling. For Hamiltonians with an underlying bounded-degree graph structure, we can learn all parameters with root mean…

Quantum Physics · Physics 2023-07-11 Haoya Li , Yu Tong , Hongkang Ni , Tuvia Gefen , Lexing Ying

A quantum state for being an eigenstate of some local Hamiltonian should be constraint by zero energy variance and consequently, the constraint is rather strong that a single eigenstate may uniquely determine the Hamiltonian. For…

Quantum Physics · Physics 2024-12-17 Xu-Dan Xie , Zheng-Yuan Xue , Dan-Bo Zhang

The local Hamiltonian (LH) problem is the canonical $\mathsf{QMA}$-complete problem introduced by Kitaev. In this paper, we show its hardness in a very strong sense: we show that the 3-local Hamiltonian problem on $n$ qubits cannot be…

Quantum Physics · Physics 2026-02-17 Nai-Hui Chia , Atsuya Hasegawa , François Le Gall , Yu-Ching Shen