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This work proposes a protocol for Fermionic Hamiltonian learning. For the Hubbard model defined on a bounded-degree graph, the Heisenberg-limited scaling is achieved while allowing for state preparation and measurement errors. To achieve…

Quantum Physics · Physics 2024-05-03 Hongkang Ni , Haoya Li , Lexing Ying

We provide a polynomial-time classical algorithm for noisy quantum circuits. The algorithm computes the expectation value of any observable for any circuit, with a small average error over input states drawn from an ensemble (e.g. the…

Quantum Physics · Physics 2024-10-15 Thomas Schuster , Chao Yin , Xun Gao , Norman Y. Yao

The question of polynomial learnability of probability distributions, particularly Gaussian mixture distributions, has recently received significant attention in theoretical computer science and machine learning. However, despite major…

Machine Learning · Computer Science 2010-05-13 Mikhail Belkin , Kaushik Sinha

We study the complexity of learning $k$-mixtures of Gaussians ($k$-GMMs) on $\mathbb{R}^d$. This task is known to have complexity $d^{\Omega(k)}$ in full generality. To circumvent this exponential lower bound on the number of components,…

Machine Learning · Computer Science 2025-04-22 Ilias Diakonikolas , Daniel M. Kane , Sushrut Karmalkar , Jasper C. H. Lee , Thanasis Pittas

A principal concern in the optimisation of parametrised quantum circuits is the presence of barren plateaus, which present fundamental challenges to the scalability of applications, such as variational algorithms and quantum machine…

Quantum Physics · Physics 2025-06-30 Nikhil Khatri , Stefan Zohren , Gabriel Matos

Fermionic linear optics (FLO) with Gaussian resources is efficiently classically simulable. We show that this is no longer the case for such quantum circuits for fermions with internal degrees of freedom, equipped with mid-circuit number…

Quantum Physics · Physics 2026-03-27 Chenfeng Cao , Yifan Tang , Jens Eisert

We introduce a framework for simulating, on an $(n+1)$-qubit quantum computer, the action of a Gaussian Bosonic (GB) circuit on a state over $2^n$ modes. Specifically, we encode the initial bosonic state's expectation values over quadrature…

Quantum Physics · Physics 2025-02-24 Alice Barthe , M. Cerezo , Andrew T. Sornborger , Martin Larocca , Diego García-Martín

Unitary and non-unitary diagonal operators are fundamental building blocks in quantum algorithms with applications in the resolution of partial differential equations, Hamiltonian simulations, the loading of classical data on quantum…

Quantum Physics · Physics 2025-01-22 Julien Zylberman , Ugo Nzongani , Andrea Simonetto , Fabrice Debbasch

Fermionic Gaussian operators are foundational tools in quantum many-body theory, numerical simulation of fermionic dynamics, and fermionic linear optics. While their structure is fully determined by two-point correlations, evaluating their…

Quantum Physics · Physics 2025-06-04 M. A. Rajabpour , MirAdel Seifi MirJafarlou , Reyhaneh Khasseh

Performing large-scale, accurate quantum simulations of many-fermion systems is a central challenge in quantum science, with applications in chemistry, materials, and high-energy physics. Despite significant progress, realizing generic…

Quantum Physics · Physics 2025-09-12 Nishad Maskara , Marcin Kalinowski , Daniel Gonzalez-Cuadra , Mikhail D. Lukin

Gaussian processes (GPs) are important models in supervised machine learning. Training in Gaussian processes refers to selecting the covariance functions and the associated parameters in order to improve the outcome of predictions, the core…

Local Hamiltonians of fermionic systems on a lattice can be mapped onto local qubit Hamiltonians. Maintaining the locality of the operators comes at the expense of increasing the Hilbert space with auxiliary degrees of freedom. In order to…

Quantum Physics · Physics 2023-02-22 Jannes Nys , Giuseppe Carleo

Quantum circuit Born machines are generative models which represent the probability distribution of classical dataset as quantum pure states. Computational complexity considerations of the quantum sampling problem suggest that the quantum…

Quantum Physics · Physics 2018-12-21 Jin-Guo Liu , Lei Wang

We propose an iterative method to safely learn the unmodeled dynamics of a nonlinear system using Bayesian Gaussian process (GP) models with polynomial kernel functions. The method maintains safety by ensuring that the system state stays…

Systems and Control · Electrical Eng. & Systems 2020-04-03 Alex Devonport , He Yin , Murat Arcak

Efficiently estimating large numbers of non-commuting observables is an important subroutine of many quantum science tasks. We present the derandomized shallow shadows (DSS) algorithm for efficiently learning a large set of non-commuting…

Quantum algorithms offer a dramatic speedup for computational problems in machine learning, material science, and chemistry. However, any near-term realizations of these algorithms will need to be heavily optimized to fit within the finite…

Estimating quantum fermionic properties is a computationally difficult yet crucial task for the study of electronic systems. Recent developments have begun to address this challenge by introducing classical shadows protocols relying on…

Quantum Physics · Physics 2024-09-09 Valentin Heyraud , Héloise Chomet , Jules Tilly

We propose and analyze an approach to realize quantum computation and simulation using fermionic particles under quantum gas microscopes. Our work is inspired by a recent experimental demonstration of large-scale quantum registers, where…

Quantum Physics · Physics 2023-06-07 Xiangkai Sun , Di Luo , Soonwon Choi

Variational quantum algorithms that are used for quantum machine learning rely on the ability to automatically differentiate parametrized quantum circuits with respect to underlying parameters. Here, we propose the rules for differentiating…

Quantum Physics · Physics 2021-11-16 Oleksandr Kyriienko , Vincent E. Elfving

We study the problem of list-decodable Gaussian covariance estimation. Given a multiset $T$ of $n$ points in $\mathbb R^d$ such that an unknown $\alpha<1/2$ fraction of points in $T$ are i.i.d. samples from an unknown Gaussian…

Data Structures and Algorithms · Computer Science 2023-05-02 Ilias Diakonikolas , Daniel M. Kane , Jasper C. H. Lee , Ankit Pensia , Thanasis Pittas