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An optimal estimator of quantum states based on a modified Kalman Filter is presented in this work. Such estimator acts after state measurement, allowing to obtain an optimal estimation of quantum state resulting in the output of any…

Quantum Physics · Physics 2014-06-20 Mario Mastriani

Many hybrid quantum-classical algorithms for the application of ground state energy estimation in quantum chemistry involve estimating the expectation value of a molecular Hamiltonian with respect to a quantum state through measurements on…

A significant hurdle for analyzing large sample data is the lack of effective statistical computing and inference methods. An emerging powerful approach for analyzing large sample data is subsampling, by which one takes a random subsample…

Methodology · Statistics 2015-11-24 Rong Zhu , Ping Ma , Michael W. Mahoney , Bin Yu

Quantum process tomography is a powerful tool for understanding quantum channels and characterizing properties of quantum devices. Inspired by recent advances using classical shadows in quantum state tomography [H.-Y. Huang, R. Kueng, and…

Quantum Physics · Physics 2024-02-12 Ryan Levy , Di Luo , Bryan K. Clark

Optimal measurement is required to obtain the quantum and classical correlations of a quantum state, and the crucial difficulty is how to acquire the maximal information about one system by measuring the other part; in other words, getting…

Quantum Physics · Physics 2021-11-18 M. Mahdian , H. Davoodi Yeganeh

We present the optimal scheme for estimating a pure qubit state by means of local measurements on N identical copies. We give explicit examples for low N. For large N, we show that the fidelity saturates the collective measurement bound up…

Quantum Physics · Physics 2009-11-07 E. Bagan , M. Baig , R. Munoz-Tapia

Quantum contextuality is a limitation on deterministic hidden variable models, testable in measurement scenarios where outcomes differ under quantum or classical descriptions due to a common set of constraints. When considering measurements…

Quantum Physics · Physics 2025-09-25 Colm Kelleher , Frédéric Holweck

We introduce a method to improve the tractability of the well-known Sample Average Approximation (SAA) without compromising important theoretical properties, such as convergence in probability and the consistency of an independent and…

Optimization and Control · Mathematics 2019-04-03 Lijian Chen

For many tasks of data analysis, we may only have the information of the explanatory variable and the evaluation of the response values are quite expensive. While it is impractical or too costly to obtain the responses of all units, a…

Computation · Statistics 2023-04-07 Wei Zheng , Ting Tian , Xueqin Wang

The quantum component in uncertainty relation can be naturally characterized by the quantum coherence of a quantum state, which is of paramount importance in quantum information science. Here, we experimentally investigate quantum…

Quantum Physics · Physics 2022-04-25 Lu Liu , Ting Zhang , Xiao Yuan , He Lu

In this study, we derive Probably Approximately Correct (PAC) bounds on the asymptotic sample-complexity for RL within the infinite-horizon Markov Decision Process (MDP) setting that are sharper than those in existing literature. The…

Machine Learning · Computer Science 2025-07-17 Mohit Prashant , Arvind Easwaran

We propose a resource-efficient shadow-tomography scheme using equatorial-stabilizer measurements generated from subsets of Clifford unitaries. For $n$-qubit systems, equatorial-stabilizer-based shadow-tomography schemes can estimate $M$…

Quantum Physics · Physics 2025-08-01 Guedong Park , Yong Siah Teo , Hyunseok Jeong

Estimating the trace of quantum state powers, $\text{Tr}(\rho^k)$, for $k$ identical quantum states is a fundamental task with numerous applications in quantum information processing, including nonlinear function estimation of quantum…

Quantum Physics · Physics 2025-09-03 Myeongjin Shin , Junseo Lee , Seungwoo Lee , Kabgyun Jeong

In quantum mechanics, wave functions and density matrices represent our knowledge about a quantum system and give probabilities for the outcomes of measurements. If the combined dynamics and measurements on a system lead to a density matrix…

Quantum Physics · Physics 2016-12-07 D. Tan , M. Naghiloo , K. Mølmer , K. W. Murch

We study the tradeoff between sample complexity and round complexity in on-demand sampling, where the learning algorithm adaptively samples from $k$ distributions over a limited number of rounds. In the realizable setting of…

Machine Learning · Computer Science 2025-11-20 Nika Haghtalab , Omar Montasser , Mingda Qiao

The generalized smooth condition, $(L_{0},L_{1})$-smoothness, has triggered people's interest since it is more realistic in many optimization problems shown by both empirical and theoretical evidence. Two recent works established the…

Machine Learning · Computer Science 2023-10-31 Zijian Liu , Srikanth Jagabathula , Zhengyuan Zhou

The computation of \(\operatorname{tr}(AB)\) is essential in quantum science and artificial intelligence, yet classical methods for \( d \)-dimensional matrices \( A \) and \( B \) require \( O(d^2) \) complexity, which becomes infeasible…

Quantum Physics · Physics 2025-10-31 Yu Wang

Identifying independence between two random variables or correlated given their samples has been a fundamental problem in Statistics. However, how to do so in a space-efficient way if the number of states is large is not quite well-studied.…

Data Structures and Algorithms · Computer Science 2022-11-21 Zhenhao Gu , Hao Zhang

Submodular functions are set functions mapping every subset of some ground set of size $n$ into the real numbers and satisfying the diminishing returns property. Submodular minimization is an important field in discrete optimization theory…

Data Structures and Algorithms · Computer Science 2020-01-16 Yassine Hamoudi , Patrick Rebentrost , Ansis Rosmanis , Miklos Santha

Quantum computers solve ever more complex tasks using steadily growing system sizes. Characterizing these quantum systems is vital, yet becoming increasingly challenging. The gold-standard is quantum state tomography (QST), capable of fully…