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In quantum information theory, the reliable and effective detection of entanglement is of paramount importance. However, given an unknown state, assessing its entanglement is a challenging task. To attack this problem, we investigate the…

Quantum Physics · Physics 2015-12-09 Jochen Szangolies , Hermann Kampermann , Dagmar Bruß

The creation complexity of a quantum state is the minimum number of elementary gates required to create it from a basic initial state. The creation complexity of quantum states is closely related to the complexity of quantum circuits, which…

Quantum Physics · Physics 2022-02-11 Zixuan Hu , Sabre Kais

We prove that any three linearly independent pure quantum states can always be locally distinguished with nonzero probability regardless of their dimension, entanglement, or multipartite structure. Almost always, all three states can be…

Quantum Physics · Physics 2015-06-26 Somshubhro Bandyopadhyay , Jonathan Walgate

We investigate the extent to which we can establish whether or not two quantum systems have been prepared in the same state. We investigate the possibility of universal unambiguous state comparison. We show that it is impossible to…

Quantum Physics · Physics 2009-11-07 Stephen M. Barnett , Anthony Chefles , Igor Jex

Accurate control of quantum states is crucial for quantum computing and other quantum technologies. In the basic scenario, the task is to steer a quantum system towards a target state through a sequence of control operations. Determining…

Quantum Physics · Physics 2024-06-14 Yan Zhu , Tailong Xiao , Guihua Zeng , Giulio Chiribella , Ya-Dong Wu

Quantum information science has profoundly changed the ways we understand, store, and process information. A major challenge in this field is to look for an efficient means for classifying quantum state. For instance, one may want to…

Quantum Physics · Physics 2017-05-03 Yue-Chi Ma , Man-Hong Yung

Quantum state discrimination is a fundamental concept in quantum information theory, which refers to a class of techniques to identify a specific quantum state through a positive operator-valued measure. In this work, we investigate how…

Quantum Physics · Physics 2025-07-09 Hyunho Cha , Jungwoo Lee

We describe a class of programmable devices that can discriminate between two quantum states. We consider two cases. In the first, both states are unknown. One copy of each of the unknown states is provided as input, or program, for the two…

Quantum Physics · Physics 2009-11-13 Janos A. Bergou , Vladimir Buzek , Edgar Feldman , Ulrike Herzog , Mark Hillery

Entanglement is a fundamental aspect of quantum physics, both conceptually and for its many applications. Classifying an arbitrary multipartite state as entangled or separable -- a task referred to as the separability problem -- poses a…

We address the problem of distinguishing among a finite collection of quantum states, when the states are not entirely known. For completely specified states, necessary and sufficient conditions on a quantum measurement minimizing the…

Quantum Physics · Physics 2009-11-11 Noam Elron , Yonina C. Eldar

Quantum state filtering is a variant of the unambiguous state discrimination problem: the states are grouped in sets and we want to determine to which particular set a given input state belongs.The simplest case, when the N given states are…

Quantum Physics · Physics 2009-11-11 Janos A. Bergou , Mark Hillery

In certain classes of physical quantum systems, the exponentially large state space "fragments" into many low-dimensional, dynamically disconnected subspaces. We introduce a learning problem known as fragment classification, where given a…

Quantum Physics · Physics 2026-05-08 Mikhail Mints , Eric R. Anschuetz

The quantum separability problem consists in deciding whether a bipartite density matrix is entangled or separable. In this work, we propose a machine learning pipeline for finding approximate solutions for this NP-hard problem in…

Quantum Physics · Physics 2023-12-12 Balthazar Casalé , Giuseppe Di Molfetta , Sandrine Anthoine , Hachem Kadri

From the NP-hardness of the quantum separability problem and the relation between bipartite entanglement and the secret key correlations, it is shown that the problem deciding whether a given quantum state has secret correlations in it or…

Quantum Physics · Physics 2015-10-30 Jae-Weon Lee , DoYong Kwon , Jaewan Kim

Quantum k-SAT (the problem of determining whether a k-local Hamiltonian is frustration-free) is known to be QMA_1-complete for k >= 3, and hence likely hard for quantum computers to solve. Building on a classical result of Alon and Shapira,…

Quantum Physics · Physics 2025-09-03 Ashley Montanaro , Changpeng Shao , Dominic Verdon

For quantum systems with a total dimension greater than six, the positive partial transposition (PPT) criterion is sufficient but not necessary to decide the non-separability of quantum states. Here, we present an Automated Machine Learning…

Quantum Physics · Physics 2021-09-22 Caio B. D. Goes , Askery Canabarro , Eduardo I. Duzzioni , Thiago O. Maciel

A foundational question in quantum computational complexity asks how much more useful a quantum state can be in a given task than a comparable, classical string. Aaronson and Kuperberg showed such a separation in the presence of a quantum…

Quantum Physics · Physics 2021-04-16 Nicholas LaRacuente

Quantum technologies require methods for preparing and manipulating entangled multiparticle states. However, the problem of determining whether a given quantum state is entangled or separable is known to be an NP-hard problem in general,…

Quantum Physics · Physics 2022-10-17 M. A. Gavreev , A. S. Mastiukova , E. O. Kiktenko , A. K. Fedorov

A classification of multipartite entanglement in qubit systems is introduced for pure and mixed states. The classification is based on the robustness of the said entanglement against partial trace operation. Then we use current machine…

Quantum Physics · Physics 2022-10-17 F. El Ayachi , M. El Baz

Quantum state discrimination involves identifying a given state out of a set of possible states. When the states are mutually orthogonal, perfect state discrimination is always possible using a global measurement. In the case of…

Quantum Physics · Physics 2023-09-13 Scott M. Cohen