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Quantum state discrimination is a fundamental primitive in quantum statistics where one has to correctly identify the state of a system that is in one of two possible known states. A programmable discrimination machine performs this task…

Quantum Physics · Physics 2015-05-19 G. Sentís , E. Bagan , J. Calsamiglia , R. Munoz-Tapia

We investigate the discrimination of pure-mixed (quantum filtering) and mixed-mixed states and compare their optimal success probability with the one for discriminating other pairs of pure states superposed by the vectors included in the…

Quantum Physics · Physics 2021-12-24 Jin-Hua Zhang , Fu-Lin Zhang , Zhi-Xi Wang , Hui Yang , Shao-Ming Fei

We find an optimal quantum cloning machine, which clones qubits of arbitrary symmetrical distribution around the Bloch vector with the highest fidelity. The process is referred to as phase-independent cloning in contrast to the standard…

Quantum Physics · Physics 2010-11-02 Karol Bartkiewicz , Adam Miranowicz

In this work,We investigate the problem of secretly broadcasting of three-qubit entangled state between two distant partners. The interesting feature of this problem is that starting from two particle entangled state shared between two…

Quantum Physics · Physics 2009-11-13 Satyabrata Adhikari , B. S. Choudhury

A quantum computer is a hypothetical device in which the laws of quantum mechanics are used to introduce a degree of parallelism into computations and which could therefore significantly improve on the computational speed of a classical…

Quantum Physics · Physics 2007-05-23 P. Blythe , B. Varcoe

The ability to realize high-fidelity quantum communication is one of the many facets required to build generic quantum computing devices. In addition to quantum processing, sensing, and storage, transferring the resulting quantum states…

Quantum state elimination measurements tell us what states a quantum system does not have. This is different from state discrimination, where one tries to determine what the state of a quantum system is, rather than what it is not. Apart…

The transmission of quantum information between different parts of a quantum computer is of fundamental importance. Spin chains have been proposed as quantum channels for transferring information. Different configurations for the spin…

Quantum Physics · Physics 2011-08-30 Analia Zwick , Gonzalo A. Alvarez , Joachim Stolze , Omar Osenda

This work investigates which sets of quantum states give rise to the highest achievable success probability in minimum-error state discrimination if multiple copies of the unknown state are given. Specifically, we consider uniformly…

State-dependent cloning machines that have so far been considered either deterministically copy a set of states approximately, or probablistically copy them exactly. In considering the case of two equiprobable pure states, we derive the…

Quantum Physics · Physics 2009-10-31 Anthony Chefles , Stephen M. Barnett

State estimation is usually analyzed in the situation when copies are in a product state, either mixed or pure. We investigate here the concept of state estimation on correlated copies. We analyze state estimation on correlated N qubit…

Quantum Physics · Physics 2009-11-10 Rafal Demkowicz-Dobrzanski

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

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

While the no-cloning theorem, which forbids the perfect copying of quantum states, is well-known as one of the defining features of quantum mechanics, the question of how well the theory allows a state to be cloned is yet to be completely…

Quantum Physics · Physics 2013-09-25 Alastair Kay , Ravishankar Ramanathan , Dagomir Kaszlikowski

The classical signal splitting and copying are not possible in quantum mechanics. Specifically, one cannot copy the basis up and down states of the input (I) two-state system (qubit, spin) into the copy (C) and duplicate-copy (D) two-state…

Quantum Physics · Physics 2014-11-18 Dima Mozyrsky , Vladimir Privman

The impossibility of simultaneously cloning non-orthogonal states lies at the foundations of quantum theory. Even when allowing for approximation errors, cloning an arbitrary unknown pure state requires as many initial copies as needed to…

Quantum Physics · Physics 2026-04-17 Nikhil Bansal , Matthias C. Caro , Gaurav Mahajan

Distributed quantum computing supports combining the computational power of multiple quantum devices to overcome the limitations of individual devices. Circuit cutting techniques enable the distribution of quantum computations via classical…

Quantum Physics · Physics 2024-08-06 Marvin Bechtold , Johanna Barzen , Frank Leymann , Alexander Mandl

Operations that are trivial in the classical world, like accessing information without introducing any change or disturbance, or like copying information, become non-trivial in the quantum world. In this note we discuss several limitations…

Quantum Physics · Physics 2016-08-10 Marco Piani

We establish the best possible approximation to a perfect quantum cloning machine which produces two clones out of a single input. We analyze both universal and state-dependent cloners. The maximal fidelity of cloning is shown to be 5/6 for…

Quantum Physics · Physics 2009-10-30 D. Bruss , D. P. DiVincenzo , A. Ekert , C. A. Fuchs , C. Macchiavello , J. A. Smolin

From the perspective of quantum information theory, a system so simple as one restricted to just two nonorthogonal states can be surprisingly rich in physics. In this paper, we explore the extent of this statement through a review of three…

Quantum Physics · Physics 2007-05-23 Christopher A. Fuchs