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We survey various recent results that rigorously study the complexity of learning quantum states. These include progress on quantum tomography, learning physical quantum states, alternate learning models to tomography and learning classical…

Quantum Physics · Physics 2023-06-01 Anurag Anshu , Srinivasan Arunachalam

We define the algorithmic complexity of a quantum state relative to a given precision parameter, and give upper bounds for various examples of states. We also establish a connection between the entanglement of a quantum state and its…

Quantum Physics · Physics 2009-11-11 Caterina Mora , Hans Briegel

Quantum circuit complexity is a fundamental concept whose importance permeates quantum information, computation, many-body physics and high-energy physics. While extensively studied in closed systems, its characterization and behaviors in…

Quantum Physics · Physics 2025-08-28 Zhenyu Du , Zi-Wen Liu , Xiongfeng Ma

Quantum complexity measures the difficulty of realizing a quantum process, such as preparing a state or implementing a unitary. We present an approach to quantifying the thermodynamic resources required to implement a process if the…

Scientists have demonstrated that quantum computing has presented novel approaches to address computational challenges, each varying in complexity. Adapting problem-solving strategies is crucial to harness the full potential of quantum…

Computational Complexity · Computer Science 2024-09-13 Arash Vaezi , Ali Movaghar , Mohammad Ghodsi , Seyed Mohammad Hussein Kazemi , Negin Bagheri Noghrehy , Seyed Mohsen Kazemi

Quantum information processing and computing tasks can be understood as quantum networks, comprising quantum states and channels and possible physical transformations on them. It is hence pertinent to estimate the change in informational…

Quantum Physics · Physics 2026-03-17 Sohail , Vivek Pandey , Uttam Singh , Siddhartha Das

In analogy of classical Kolmogorov complexity we develop a theory of the algorithmic information in bits contained in any one of continuously many pure quantum states: quantum Kolmogorov complexity. Classical Kolmogorov complexity coincides…

Quantum Physics · Physics 2007-05-23 Paul Vitanyi

Quantum complexity is emerging as a key property of many-body systems, including black holes, topological materials, and early quantum computers. A state's complexity quantifies the number of computational gates required to prepare the…

In this paper we give a definition for the Kolmogorov complexity of a pure quantum state. In classical information theory the algorithmic complexity of a string is a measure of the information needed by a universal machine to reproduce the…

Quantum Physics · Physics 2007-05-23 C. Mora , H. J. Briegel

This thesis establishes a number of connections between foundational issues in quantum theory, and some quantum information applications. It starts with a review of quantum contextuality and non-locality, multipartite entanglement…

Quantum Physics · Physics 2007-05-23 Ernesto F. Galvao

We discuss a classical complexity of finite-dimensional unitary transformations, which can been seen as a computable approximation of classical descriptional complexity of a unitary transformation acting on a set of qubits.

Quantum Physics · Physics 2023-04-03 Alexei Kaltchenko

We shed new light on entanglement measures in multipartite quantum systems by taking a computational-complexity approach toward quantifying quantum entanglement with two familiar notions--approximability and distinguishability. Built upon…

Quantum Physics · Physics 2007-05-23 Tomoyuki Yamakami

The quantum brachistochrone problem addresses the fundamental challenge of achieving the quantum speed limit in applications aiming to realize a given unitary operation in a quantum system. Specifically, it looks into optimization of the…

Quantum Physics · Physics 2024-05-24 S. Malikis , V. Cheianov

A quantum computer directly manipulates information stored in the state of quantum mechanical systems. The available operations have many attractive features but also underly severe restrictions, which complicate the design of quantum…

Quantum Physics · Physics 2015-06-26 Sos S. Agaian , Andreas Klappenecker

The vast complexity is a daunting property of generic quantum states that poses a significant challenge for theoretical treatment, especially in non-equilibrium setups. Therefore, it is vital to recognize states which are locally less…

Quantum Physics · Physics 2022-07-28 Markus Schmitt , Zala Lenarčič

We investigate probabilistic transformations of quantum states from a `source' set to a `target' set of states. Such transforms have many applications. They can be used for tasks which include state-dependent cloning or quantum state…

Quantum Physics · Physics 2015-06-05 Vedran Dunjko , Erika Andersson

Recent research has demonstrated that quantum computers can solve certain types of problems substantially faster than the known classical algorithms. These problems include factoring integers and certain physics simulations. Practical…

Quantum Physics · Physics 2009-10-30 Emanuel Knill , Raymond Laflamme , Wojciech H. Zurek

Quantum process tomography (QPT) methods aim at identifying a given quantum process. The present paper focuses on the estimation of a unitary process. This class is of particular interest because quantum mechanics postulates that the…

Quantum Physics · Physics 2024-01-23 François Verdeil , Yannick Deville

The "quantum complexity" of a unitary operator measures the difficulty of its construction from a set of elementary quantum gates. While the notion of quantum complexity was first introduced as a quantum generalization of the classical…

Quantum Physics · Physics 2021-11-02 Vir B. Bulchandani , S. L. Sondhi

The complexity of quantum computation remains poorly understood. While physicists attempt to find ways to create quantum computers, we still do not have much evidence one way or the other as to how useful these machines will be. The tools…

Quantum Physics · Physics 2007-05-23 Lance Fortnow