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Restricted Boltzmann machines (RBMs) are a class of neural networks that have been successfully employed as a variational ansatz for quantum many-body wave functions. Here, we develop an analytic method to study quantum many-body spin…

Quantum Physics · Physics 2022-10-06 Xiao-Qi Sun , Tamra Nebabu , Xizhi Han , Michael O. Flynn , Xiao-Liang Qi

Quantum state diffusion is a framework within which measurement may be described as the continuous and gradual collapse of a quantum system to an eigenstate as a result of interaction with its environment. The irreversible nature of the…

Quantum Physics · Physics 2025-09-18 Sophia M. Walls , Adam Bloss , Ian J. Ford

Quantum networks are an integral component in performing efficient computation and communication tasks that are not accessible using classical systems. A key aspect in designing an effective and scalable quantum network is generating…

Quantum Physics · Physics 2018-07-10 Sudipto Singha Roy , Himadri Shekhar Dhar , Debraj Rakshit , Aditi Sen De , Ujjwal Sen

The precision of quantum metrology is widely believed to be restricted by the Heisenberg limit, corresponding to a root mean square error that is inversely proportional to the number of independent processes probed in an experiment, N. In…

Quantum metrology with nonclassical states offers a promising route to improved precision in physical measurements. The quantum effects of Schr{\"o}dinger-cat superpositions or entanglements allow measurement uncertainties to reach below…

Quantum Physics · Physics 2025-07-11 Y. A. Yang , W. -T. Luo , J. -L. Zhang , S. -Z. Wang , Chang-Ling Zou , T. Xia , Z. -T. Lu

The optimal quantum measurements for estimating different unknown parameters in a parameterized quantum state are usually incompatible with each other. Traditional approaches to addressing the measurement incompatibility issue, such as the…

Quantum Physics · Physics 2026-02-03 Sisi Zhou , Senrui Chen

The test of modifications to quantum mechanics aimed at identifying the fundamental reasons behind the un-observability of quantum mechanical superpositions at the macro-scale is a crucial goal of modern quantum mechanics. Within the…

Quantum Physics · Physics 2014-06-03 M. Bahrami , M. Paternostro , A. Bassi , H. Ulbricht

We explore a supervised machine learning approach to estimate the entanglement entropy of multi-qubit systems from few experimental samples. We put a particular focus on estimating both aleatoric and epistemic uncertainty of the network's…

Quantum Physics · Physics 2024-01-04 Maximilian Rieger , Moritz Reh , Martin Gärttner

We describe a further development of the stochastic state selection method, which is a kind of Monte Carlo method we have proposed in order to numerically study large quantum spin systems. In the stochastic state selection method we make a…

Statistical Mechanics · Physics 2015-05-13 Tomo Munehisa , Yasuko Munehisa

We show relations between superposition of macroscopically distinct states and entanglement. These relations lead to the important conclusion that if a state contains superposition of macroscopically distinct states, the state also contains…

Quantum Physics · Physics 2010-01-25 Tomoyuki Morimae

We discuss an interferometric approach to the estimation of quantum mechanical damping. We study specific classes of entangled and separable probe states consisting of superpositions of coherent states. Based on the assumption of limited…

Quantum Physics · Physics 2007-05-23 Hannah Venzl , Matthias Freyberger

Quantum-enhanced metrology surpasses classical metrology by improving estimation precision scaling with a resource $N$ (e.g., particle number or energy) from $1/\sqrt{N}$ to $1/N$. Through the use of nonlinear effects, Roy and…

Quantum Physics · Physics 2025-04-07 Noah Lordi , John Drew Wilson , Murray J. Holland , Joshua Combes

Quantum metrology allows for a huge boost in the precision of parameters estimation. However, it seems to be extremely sensitive on the noise. Bound entangled states are states with large amount of noise what makes them unusable for almost…

Quantum Physics · Physics 2015-12-09 L. Czekaj , A. Przysiezna , M. Horodecki , P. Horodecki

Massive objects in spatial superposition may provide insights into the interplay between quantum mechanics and gravity. Cold atomic interferometers offer a promising platform due to extended matter-wave coherence times and precise…

Quantum Gases · Physics 2026-05-13 Han Zhang , Yong-Kui Wang , Yi Zheng , Hai-Tao Bai , Bing Yang

Quantum metrology aims to exploit quantum phenomena to overcome classical limitations in the estimation of relevant parameters. We consider a probe undergoing a phase shift $\varphi$ whose generator is randomly sampled according to a…

Quantum Physics · Physics 2017-06-07 Rozhin Yousefjani , Rosanna Nichols , Shahriar Salimi , Gerardo Adesso

The area law conjecture states that the entanglement entropy of a region of space in the ground state of a gapped, local Hamiltonian only grows like the surface area of the region. We show that, for any quantum state that fulfills an area…

Quantum Physics · Physics 2019-05-22 Henrik Wilming , Jens Eisert

The reconstruction of quantum states from experimental measurements, often achieved using quantum state tomography (QST), is crucial for the verification and benchmarking of quantum devices. However, performing QST for a generic…

Quantum Physics · Physics 2024-10-07 Zhen Qin , Casey Jameson , Zhexuan Gong , Michael B. Wakin , Zhihui Zhu

Non-Gaussian bosonic states are ubiquitous in interacting light--matter systems, many-body platforms, and relativistic quantum field settings, but their quantitative characterization is hindered by the infinite-dimensional Hilbert space and…

Quantum Physics · Physics 2026-03-17 Federico Centrone , Juan Pablo Paz , Augusto Roncaglia

Several experiments and experimental proposals for the production of macroscopic superpositions naturally lead to states of the general form $|\phi_1>^{\otimes N}+|\phi_2>^{\otimes N}$, where the number of subsystems $N$ is very large, but…

Quantum Physics · Physics 2016-08-16 Wolfgang Dür , Christoph Simon , J. Ignacio Cirac

The entanglement spectrum, i.e., the full distribution of Schmidt eigenvalues of the reduced density matrix, contains more information than the conventional entanglement entropy and has been studied recently in several many-particle…

Strongly Correlated Electrons · Physics 2011-02-02 Maurizio Fagotti , Pasquale Calabrese , Joel E. Moore