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Learning faithful representations of quantum states is crucial to fully characterizing the variety of many-body states created on quantum processors. While various tomographic methods such as classical shadow and MPS tomography have shown…

Non-Gaussianity, a distinctive characteristic of bosonic quantum states, is pivotal in advancing quantum networks, fault-tolerant quantum computing, and high-precision metrology. Verifying the quantum nature of a state, particularly its…

In this paper we extend the work of Smith and Papamichail (1999) and present fast approximate Bayesian algorithms for learning in complex scenarios where at any time frame, the relationships between explanatory state space variables can be…

Machine Learning · Computer Science 2013-01-30 Raffaella Settimi , Jim Q. Smith , A. S. Gargoum

The notion of partial trace of a density operator is essential for the understanding of the entanglement and separability properties of quantum states. In this paper we investigate these notions putting an emphasis on the geometrical…

Quantum Physics · Physics 2023-03-21 Nuno Costa Dias , Maurice de Gosson , Joao Nuno Prata

We theoretically propose and experimentally demonstrate a nonclassicality test of single-mode field in phase space, which has an analogy with the nonlocality test proposed by Banaszek and Wodkiewicz [Phys. Rev. Lett. 82, 2009 (1999)]. Our…

Quantum Physics · Physics 2015-06-11 Jiyong Park , Junhua Zhang , Jaehak Lee , Se-Wan Ji , Mark Um , Dingshun Lv , Kihwan Kim , Hyunchul Nha

We analyze the Heisenberg limit on phase estimation for Gaussian states. In the analysis, no reference to a phase operator is made. We prove that the squeezed vacuum state is the most sensitive for a given average photon number. We provide…

Quantum Physics · Physics 2007-05-23 Alex Monras

Robust, accurate and efficient quantum tomography is key for future quantum technologies. Traditional methods are impractical for even medium sized systems and are not robust against noise and errors. Here we report on an experimental…

Quantum Physics · Physics 2016-07-27 Robert J. Chapman , Christopher Ferrie , Alberto Peruzzo

Quantum fidelity is a measure to quantify the closeness of two quantum states. In an operational sense, it is defined as the minimal overlap between the probability distributions of measurement outcomes and the minimum is taken over all…

Quantum Physics · Physics 2019-07-24 Changhun Oh , Changhyoup Lee , Leonardo Banchi , Su-Yong Lee , Carsten Rockstuhl , Hyunseok Jeong

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

Quantum state estimation is important for various quantum information processes, including quantum communications, computation, and metrology, which require the characterization of quantum states for evaluation and optimization. We present…

Quantum Physics · Physics 2026-04-15 C. Vargas , L. Pereira , A. Delgado

Boson Sampling represents a promising approach to obtain an evidence of the supremacy of quantum systems as a resource for the solution of computational problems. The classical hardness of Boson Sampling has been related to the so called…

Quantum Physics · Physics 2016-11-09 Ludovico Latmiral , Nicolò Spagnolo , Fabio Sciarrino

Gaussian process regression is a powerful Bayesian nonlinear regression method. Recent research has enabled the capture of many types of observations using non-Gaussian likelihoods. To deal with various tasks in spatial modeling, we benefit…

Machine Learning · Statistics 2025-08-26 Yuta Shikuri

We consider an instance of black-box quantum metrology in the Gaussian framework, where we aim to estimate the amount of squeezing applied on an input probe, without previous knowledge on the phase of the applied squeezing. By taking the…

Boson sampling has emerged as an important tool to demonstrate the difference between quantum and classical computers and has attracted the interest of experimentalists and theoreticians. In this work we study Boson sampling from general,…

Quantum Physics · Physics 2024-03-27 Craig S. Hamilton , Igor Jex

Phase estimation with potentially large phase values, i.e., with large dynamic range, has many applications in quantum metrology, for example to atomic clocks. A recently proposed phase estimation scheme approaches the Heisenberg scaling in…

Quantum Physics · Physics 2026-03-17 Tyler G. Thurtell , Akimasa Miyake

Consider two bosonic modes which are prepared in one of two possible Gaussian states with the same local energy: either a tensor-product thermal state (with zero correlations) or a separable Gaussian state with maximal correlations (with…

Quantum Physics · Physics 2019-08-06 Gaetana Spedalieri , Stefano Pirandola , Samuel L. Braunstein

Quantum correlations are at the core of the power of quantum information and are necessary to reach a quantum computational advantage. In the context of continuous-variable quantum systems, another necessary ressource for quantum advantages…

Quantum Physics · Physics 2024-07-26 Carlos E. Lopetegui , Mathieu Isoard , Nicolas Treps , Mattia Walschaers

We investigate Gaussian quantum states in view of their exceptional role within the space of all continuous variables states. A general method for deriving extremality results is provided and applied to entanglement measures, secret key…

Quantum Physics · Physics 2009-11-11 Michael M. Wolf , Geza Giedke , J. Ignacio Cirac

In nature, active inference agents must learn how observations of the world represent the state of the agent. In engineering, the physics behind sensors is often known reasonably accurately and measurement functions can be incorporated into…

Systems and Control · Electrical Eng. & Systems 2024-09-20 Wouter M. Kouw

We develop a quantum learning scheme for binary discrimination of coherent states of light. This is a problem of technological relevance for the reading of information stored in a digital memory. In our setting, a coherent light source is…

Quantum Physics · Physics 2015-07-09 Gael Sentís , Madalin Guta , Gerardo Adesso