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Uranium concentrations in groundwater in a localized area of a site exceed the USEPA Maximum Contaminant Level (MCL) by a factor of one thousand. Although the groundwater seepage velocity ranges up…
Separability of diagonal symmetric states: a quadratic conic optimization problem
We study the separability problem in mixtures of Dicke states i.e., the separability of the so-called Diagonal Symmetric (DS) states. First, we show that separability in the case of DS in $C^d\otimes…
Device-Independent Witnesses of Entanglement Depth from Two-Body Correlators.
- A. Aloy, Jordi Tura i Brugués, F. Baccari, A. Acín, M. Lewenstein, R. Augusiak
- Computer SciencePhysical review letters
- 16 July 2018
This work obtains device-independent witnesses of entanglement depth (DIWEDs) using the Bell inequalities introduced in [J. Tura et al], and obtains a certificate of optimality via a semidefinite program, based on a relaxation of the quantum marginal problem, which suggests a clear pattern on k-producible bounds for large system sizes.
Bell correlation depth in many-body systems
We address the question of assessing the number of particles sharing genuinely nonlocal correlations in a multipartite system. While the interest in multipartite nonlocality has grown in recent…
Bell Correlations at Ising Quantum Critical Points.
A maximal violation for infinite-range interactions (α=0), namely, when interactions and correlations are themselves permutationally invariant, is observed.
Optimization of device-independent witnesses of entanglement depth from two-body correlators
- Jordi Tura i Brugués, A. Aloy, F. Baccari, A. Acín, M. Lewenstein, R. Augusiak
- Computer SciencePhysical Review A
- 22 March 2019
The problem of finding the $k$-producible bounds of such DIWEDs under different assumptions is considered, not surprisingly, with the weakest assumptions, only for a relatively small number of parties; however, one can still learn interesting features from these solutions that motivate the search on larger systems under the assumption that these features persist.
The quantum marginal problem for symmetric states: applications to variational optimization, nonlocality and self-testing
In this paper, we present a method to solve the quantum marginal problem for symmetric d-level systems. The method is built upon an efficient semi-definite program that uses the compatibility…
Bounding the fidelity of quantum many-body states from partial information
An algorithm to lower bound the fidelity between quantum many-body states only from partial information, such as the one accessible by few-body observables is formulated, which makes this method useful in realistic experimental situations.
Entangled symmetric states and copositive matrices
Entanglement in symmetric quantum states and the theory of copositive matrices are intimately related concepts. For the simplest symmetric states, i.e., the diagonal symmetric (DS) states, it has…
Storage capacity and learning capability of quantum neural networks
- M. Lewenstein, A. Gratsea, Andreu Riera-Campeny, A. Aloy, V. Kasper, A. Sanpera
- Computer ScienceQuantum Science and Technology
- 11 November 2020
We study the storage capacity of quantum neural networks (QNNs), described by completely positive trace preserving (CPTP) maps acting on an N-dimensional Hilbert space. We demonstrate that attractor…