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A general tool for description of open quantum systems is given by the formalism of quantum operations. Most important of them are trace-preserving maps also known as quantum channels. We discuss those conditions on quantum channels under…

Quantum Physics · Physics 2013-07-10 Alexey E. Rastegin

Classical shadow tomography provides an efficient method for predicting functions of an unknown quantum state from a few measurements of the state. It relies on a unitary channel that efficiently scrambles the quantum information of the…

Quantum Physics · Physics 2022-02-01 Hong-Ye Hu , Yi-Zhuang You

Analysis of quantum processes, especially in the context of noise, errors, and decoherence is essential for the improvement of quantum devices. An intuitive representation of those processes modeled by quantum channels are Pauli transfer…

Quantum Physics · Physics 2025-07-25 Lukas Hantzko , Lennart Binkowski , Sabhyata Gupta

It is established that both discrete and continuous semigroups of unital quantum channels are eventually mixed unitary. This result is novel even for the subclass of Schur maps and stands in sharp contrast to the resolution of the…

Operator Algebras · Mathematics 2026-02-10 B V Rajarama Bhat , Repana Devendra

The coexistence of quantum and classical signals over the same optical fiber with minimal degradation of the transmitted quantum information is critical for operating large-scale quantum networks over the existing communications…

We investigate the possibility of performing full quantum tomography based on the homogeneous time evolution of a single expectation value. Remarkably, every non-trivial binary measurement evolved by any quantum channel, except for a null…

Mathematical Physics · Physics 2025-02-19 Hjalmar Rall , Michael M. Wolf

Non-signalling quantum channels -- relevant in, e.g., the study of Bell and Einstein-Podolsky-Rosen scenarios -- may be simulated via affine combinations of local operations in bipartite scenarios. Moreover, when these channels correspond…

Quantum Physics · Physics 2022-10-05 Paulo J. Cavalcanti , John H. Selby , Jamie Sikora , Ana Belén Sainz

Semiclassical systems being symmetric under Lie group are studied. A state of a semiclassical system may be viewed as a set (X,f) of a classical state X and a quantum state f in the external classical background X. Therefore, the set of all…

Mathematical Physics · Physics 2007-05-23 Oleg Shvedov

We undertake a study of the notion of a quantum graph over arbitrary finite-dimensional $C^*$-algebras $B$ equipped with arbitrary faithful states. Quantum graphs are realised principally as either certain operators on $L^2(B)$, the quantum…

Operator Algebras · Mathematics 2024-11-27 Matthew Daws

In circuit-based quantum computing, the available gate set typically consists of single-qubit gates acting on each individual qubit and at least one entangling gate between pairs of qubits. In certain physical architectures, however, some…

Quantum Physics · Physics 2022-09-23 M. Pechal , G. Salis , M. Ganzhorn , D. J. Egger , M. Werninghaus , S. Filipp

We derive an intuitive and novel method to represent nodes in a graph with special unitary operators, or quantum operators, which does not require parameter training and is competitive with classical methods on scoring similarity between…

Quantum Physics · Physics 2024-07-22 Andrew Vlasic , Salvador Aguinaga

The scheme for entanglement teleportation is proposed to incorporate multipartite entanglement of four qubits as a quantum channel. Based on the invariance of entanglement teleportation under arbitrary two-qubit unitary transformation, we…

Quantum Physics · Physics 2009-11-07 Jinhyoung Lee , Hyegeun Min , Sung Dahm Oh

Noise forms a central obstacle to effective quantum information processing. Recent experimental advances have enabled the tailoring of noise properties through Pauli twirling, transforming arbitrary noise channels into Pauli channels. This…

Quantum Physics · Physics 2026-02-10 Joris Kattemölle , Balázs Gulácsi , Guido Burkard

While the structure of entangled quantum states is relatively well understood, the characterization of entangled measurements, especially in multipartite and high-dimensional settings, remains far less developed. In this work, we introduce…

Quantum Physics · Physics 2026-05-28 Jef Pauwels , Cyril Branciard , Alejandro Pozas-Kerstjens , Nicolas Gisin

Finite-time Markovian channels, unlike their infinitesimal counterparts, do not form a convex set. As a particular instance of this observation, we consider the problem of mixing the three Pauli channels, conservatively assumed to be…

Quantum Physics · Physics 2020-06-02 Vinayak Jagadish , R. Srikanth , Francesco Petruccione

For one qubit systems, we present a short, elementary argument characterizing unital quantum operators in terms of their action on Bloch vectors. We then show how our approach generalizes to multi-qubit systems, obtaining inequalities that…

Quantum Physics · Physics 2009-11-10 P. S. Bourdon , H. T. Williams

In this work, we investigate the geometry of quantum logic gates within the holomorphic representation of quantum mechanics. We begin by embedding the physical qubit subspace into the space of holomorphic functions that are homogeneous of…

Quantum Physics · Physics 2026-04-30 M. W. AlMasri

Obtaining the expectation value of an observable on a quantum computer is a crucial step in the variational quantum algorithms. For complicated observables such as molecular electronic Hamiltonians, a common strategy is to present the…

Quantum Physics · Physics 2022-04-20 Tzu-Ching Yen , Aadithya Ganeshram , Artur F. Izmaylov

We review quantum chaos on graphs. We construct a unitary operator which represents the quantum evolution on the graph and study its spectral and wavefunction statistics. This operator is the analogue of the classical evolution operator on…

Chaotic Dynamics · Physics 2007-05-23 Tsampikos Kottos

Problem of classification of parallel quantum channels for information transfer is studied by method of ladder operators. Detailed compared to http://arxiv.org/abs/quant-ph/0702076 presentation of method of ladder operators is given.…

Quantum Physics · Physics 2008-07-02 Constantin V. Usenko
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