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The problem of quantum state classification asks how accurately one can identify an unknown quantum state that is promised to be drawn from a known set of pure states. In this work, we introduce the notion of $k$-learnability, which…

Quantum Physics · Physics 2025-10-24 Nathaniel Johnston , Benjamin Lovitz , Vincent Russo , Jamie Sikora

We introduce the problem of unsupervised classification of quantum data, namely, of systems whose quantum states are unknown. We derive the optimal single-shot protocol for the binary case, where the states in a disordered input array are…

Quantum Physics · Physics 2019-11-11 Gael Sentís , Alex Monràs , Ramon Muñoz-Tapia , John Calsamiglia , Emilio Bagan

The problem of unambiguous state discrimination consists of determining which of a set of known quantum states a particular system is in. One is allowed to fail, but not to make a mistake. The optimal procedure is the one with the lowest…

Quantum Physics · Physics 2009-11-07 Mark Hillery , Jihane Mimih

Using the properties of quantum superposition, we propose a quantum classification algorithm to efficiently perform multi-class classification tasks, where the training data are loaded into parameterized operators which are applied to the…

Quantum Physics · Physics 2022-03-09 Anqi Zhang , Xiaoyun He , Shengmei Zhao

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

We address the problem of learning an unknown unitary transformation from a finite number of examples. The problem consists in finding the learning machine that optimally emulates the examples, thus reproducing the unknown unitary maximum…

Quantum Physics · Physics 2010-07-01 A. Bisio , G. Chiribella , G. M. D'Ariano , S. Facchini , P. Perinotti

The optimal estimation of a quantum mechanical 2-state system (qubit) - with N identically prepared qubits available - is obtained by measuring all qubits simultaneously in an entangled basis. We report the experimental estimation of qubits…

Quantum Physics · Physics 2007-05-23 Th. Hannemann , D. Reiss , Ch. Balzer , W. Neuhauser , P. E. Toschek , Ch. Wunderlich

Quantum state discrimination is a fundamental information processing task that serves as a building block for numerous applications and provides implications at the foundational level. In this work, we consider minimum error discrimination…

Quantum Physics · Physics 2026-04-30 Tim Achenbach , Leevi Leppäjärvi , Hanwool Lee , Teiko Heinosaari

We consider a state discrimination problem which deals with settings of minimum-error and unambiguous discrimination systematically by introducing a margin for the probability of an incorrect guess. We analyze discrimination of three…

Quantum Physics · Physics 2012-10-12 H. Sugimoto , Y. Taninaka , A. Hayashi

Image classification, a pivotal task in multiple industries, faces computational challenges due to the burgeoning volume of visual data. This research addresses these challenges by introducing two quantum machine learning models that…

Quantum Physics · Physics 2024-03-29 Arsenii Senokosov , Alexandr Sedykh , Asel Sagingalieva , Basil Kyriacou , Alexey Melnikov

We address a problem of identifying a given pure state with one of two reference pure states, when no classical knowledge on the reference states is given, but a certain number of copies of them are available. We assume the input state is…

Quantum Physics · Physics 2009-11-11 A. Hayashi , M. Horibe , T. Hashimoto

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

The problem of determining whether a given quantum state is entangled lies at the heart of quantum information processing, which is known to be an NP-hard problem in general. Despite the proposed many methods such as the positive partial…

Quantum Physics · Physics 2018-07-18 Sirui Lu , Shilin Huang , Keren Li , Jun Li , Jianxin Chen , Dawei Lu , Zhengfeng Ji , Yi Shen , Duanlu Zhou , Bei Zeng

We study an optimized measurement that discriminates two mixed quantum states with maximum confidence for each conclusive result, thereby keeping the overall probability of inconclusive results as small as possible. When the rank of the…

Quantum Physics · Physics 2009-11-13 Ulrike Herzog

There are fundamental limits to the accuracy with which one can determine the state of a quantum system. I give an overview of the main approaches to quantum state discrimination. Several strategies exist. In quantum hypothesis testing, a…

Quantum Physics · Physics 2009-11-06 Anthony Chefles

Drawing the quantum phase diagram of a many-body system in the parameter space of its Hamiltonian can be seen as a learning problem, which implies labelling the corresponding ground states according to some classification criterium that…

Quantum Physics · Physics 2025-10-17 Mehran Khosrojerdi , Alessandro Cuccoli , Paola Verrucchi , Leonardo Banchi

We construct a device that can unambiguously discriminate between two unknown quantum states. The unknown states are provided as inputs, or programs, for the program registers and a third system, which is guaranteed to be prepared in one of…

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

Quantum information processing often requires the preparation of arbitrary quantum states, such as all the states on the Bloch sphere for two-level systems. While numerical optimization can prepare individual target states, they lack the…

Quantum Physics · Physics 2021-02-04 Tobias Haug , Wai-Keong Mok , Jia-Bin You , Wenzu Zhang , Ching Eng Png , Leong-Chuan Kwek

Quantum machine learning seeks a computational advantage in data processing by evaluating functions of quantum states, such as their similarity, that can be classically intractable to compute. For quantum advantage to be possible, however,…

Quantum machine learning promises to efficiently solve important problems. There are two persistent challenges in classical machine learning: the lack of labeled data, and the limit of computational power. We propose a novel framework that…

Quantum Physics · Physics 2022-10-25 Zhou Shangnan