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We study the process of quantum telecloning of $d$-dimensional pure quantum states using partially entangled pure states as quantum channel. This process efficiently mixes optimal universal symmetric cloning with quantum teleportation. It…

Quantum Physics · Physics 2017-12-05 Gabriel Araneda , Nataly Cisternas , Aldo Delgado

We investigate the problem of copying pure two-qubit states of a given degree of entanglement in an optimal way. Completely positive covariant quantum operations are constructed which maximize the fidelity of the output states with respect…

Quantum Physics · Physics 2009-11-10 J. Novotny , G. Alber , I. Jex

After the appearance of the no-cloning theorem, approximate quantum cloning machines (QCMs) have become one of the most well-studied subject in quantum information theory. Among several measures to quantify the performance of a QCM,…

Quantum Physics · Physics 2022-08-31 Chloe Kim , Eric Chitambar

Copying information is an elementary operation in classical information processing. However, copying seems rather different in the quantum regime. Since the discovery of the universal quantum cloning machine, much has been found from the…

Quantum Physics · Physics 2007-05-23 K. Maruyama , P. L. Knight

The cloning of quantum variables with continuous spectra is analyzed. A universal - or Gaussian - quantum cloning machine is exhibited that copies equally well the states of two conjugate variables such as position and momentum. It also…

Quantum Physics · Physics 2009-10-31 N. J. Cerf , A. Ipe , X. Rottenberg

In this paper we address the problem of optimal reconstruction of a quantum state from the result of a single measurement when the original quantum state is known to be a member of some specified set. A suitable figure of merit for this…

Quantum Physics · Physics 2007-05-23 Kieran Hunter , Erika Andersson , Claire R. Gilson , Stephen M. Barnett

No-cloning theorem is fundamental for quantum mechanics and for quantum information science that states an unknown quantum state cannot be cloned perfectly. However, we can try to clone a quantum state approximately with the optimal…

Quantum Physics · Physics 2014-10-30 Heng Fan , Yi-Nan Wang , Li Jing , Jie-Dong Yue , Han-Duo Shi , Yong-Liang Zhang , Liang-Zhu Mu

Quantum resource theories provide a mathematically rigorous way of understanding the nature of various quantum resources. An important problem in any quantum resource theory is to determine how quantum states can be converted into each…

Quantum Physics · Physics 2025-12-09 Tulja Varun Kondra , Chandan Datta , Alexander Streltsov

We propose a quantum tomography scheme for pure qudit systems which adopts random base measurements and generative learning methods, along with a built-in fidelity estimation approach to assess the reliability of the tomographic states. We…

Quantum Physics · Physics 2020-03-25 Jun Wang , Zhao-Yu Han , Song-Bo Wang , Zeyang Li , Liang-Zhu Mu , Heng Fan , Lei Wang

In this work, we extensively study the problem of broadcasting of entanglement. In the first part of the work, we reconceptualize the idea of state dependent quantum cloning machine, and in that process we introduce different types of state…

Quantum Physics · Physics 2019-03-26 Manish Kumar Shukla , Indranil Chakrabarty , Sourav Chatterjee

In the field of quantum information theory, the concept of quantum fidelity is employed to quantify the similarity between two quantum states. It has been observed that the fidelity between two states describing a bipartite quantum system…

Quantum Physics · Physics 2023-08-01 Seong-Kun Kim , Yonghae Lee

The inherent limitations of physical processes prevent the copying of arbitrary quantum states. Furthermore, even if we only aim to clone two distinct quantum states, it remains impossible unless they are mutually orthogonal. To overcome…

Quantum Physics · Physics 2025-07-24 Zhi-Hao Bi , Jing-Tao Qiu , Xiao-Dong Yu

We have found a quantum cloning machine that optimally duplicates the entanglement of a pair of $d$-dimensional quantum systems. It maximizes the entanglement of formation contained in the two copies of any maximally-entangled input state,…

Quantum Physics · Physics 2007-05-23 E. Karpov , P. Navez , N. J. Cerf

In the task of discriminating between nonorthogonal quantum states from multiple copies, the key parameters are the error probability and the resources (number of copies) used. Previous studies have considered the task of minimizing the…

We derive several bounds on fidelity between quantum states. In particular we show that fidelity is bounded from above by a simple to compute quantity we call super--fidelity. It is analogous to another quantity called sub--fidelity. For…

Quantum Physics · Physics 2008-11-19 J. A. Miszczak , Z. Puchała , P. Horodecki , A. Uhlmann , K. Życzkowski

A family of quantum cloning machines is introduced that produce two approximate copies from a single quantum bit, while the overall input-to-output operation for each copy is a Pauli channel. A no-cloning inequality is derived, describing…

Quantum Physics · Physics 2009-10-31 Nicolas J. Cerf

It is well known that it is impossible to clone an arbitrary quantum state. However, this inability does not lead directly to no-cloning of quantum coherence. Here, we show that it is impossible to clone the coherence of an arbitrary…

We investigate several classes of state-dependent quantum cloners for three-level systems. These cloners optimally duplicate some of the four maximally-conjugate bases with an equal fidelity, thereby extending the phase-covariant qubit…

Quantum Physics · Physics 2009-11-07 Nicolas J. Cerf , Thomas Durt , Nicolas Gisin

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

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
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