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We study two complementary diagnostics of bipartite quantum channels, namely fidelity preservation across different classes of input states and entanglement generation from product inputs, given by properly defined entangling power for…

Quantum Physics · Physics 2026-05-27 Marcin Rudziński , Gianluigi Tartaglione , Karol Życzkowski

Quantum channels, which are completely positive and trace preserving mappings, can alter the dimension of a system; e.g., a quantum channel from a qubit to a qutrit. We study the convex set properties of dimension-altering quantum channels,…

Quantum Physics · Physics 2016-11-22 Dong-Sheng Wang

The tight, in a sense, lower estimates of diamond-norm distance from a given quantum channel to the sets of degradable, antidegradable and entanglement-breaking channels are obtained via the tight continuity bounds for quantum mutual…

Quantum Physics · Physics 2019-10-18 M. E. Shirokov , A. V. Bulinski

Large weak values have been used to amplify the sensitivity of a linear response signal for detecting changes in a small parameter, which has also enabled a simple method for precise parameter estimation. However, producing a large weak…

Quantum Physics · Physics 2014-07-23 Shengshi Pang , Justin Dressel , Todd A. Brun

We define and study the properties of channels which are analogous to unital qubit channels in several ways. A full treatment can be given only when the dimension d is a prime power, in which case each of the (d+1) mutually unbiased bases…

Quantum Physics · Physics 2009-11-13 M. Nathanson , M. B. Ruskai

Entanglement is an essential resource for various quantum-information tasks. When a target system shares entanglement with another memory system and is stored reliably, one can use entanglement at a later time -- this is quantum memory. In…

Quantum Physics · Physics 2024-10-18 Gelo Noel M. Tabia , Chung-Yun Hsieh

We study entanglement-assisted quantum and classical communication over a single use of a quantum channel, which itself can correspond to a finite number of uses of a channel with arbitrarily correlated noise. We obtain characterizations of…

Quantum Physics · Physics 2013-06-20 Nilanjana Datta , Min-Hsiu Hsieh

Here we revisit one of the prototypical tasks for characterizing the structure of noise in quantum devices: estimating every eigenvalue of an $n$-qubit Pauli noise channel to error $\epsilon$. Prior work [14] proved no-go theorems for this…

Quantum Physics · Physics 2025-09-16 Sitan Chen , Weiyuan Gong

The single-letter characterisation of the entanglement-assisted capacity of a quantum channel is one of the seminal results of quantum information theory. In this paper, we consider a modified communication scenario in which the receiver is…

Quantum Physics · Physics 2024-09-16 Kaiyuan Ji , Bartosz Regula , Mark M. Wilde

We prove a one-shot "minimax" converse bound for quantum channel coding assisted by positive partial transpose channels between sender and receiver. The bound is similar in spirit to the converse by Polyanskiy, Poor, and Verdu [IEEE Trans.…

Quantum Physics · Physics 2015-06-01 Joseph M. Renes

Extensive research has been dedicated to the asymptotic theory of quantum metrology, where the goal is to determine the ultimate precision limit of quantum channel estimation when many accesses to the channel are allowed. The ultimate limit…

Quantum Physics · Physics 2025-10-03 Qiushi Liu , Yuxiang Yang

Entanglement detection is a fundamental task in quantum information science, serving as a cornerstone for quantum benchmarking and foundational studies. With an increasing qubit number that can be effectively controlled, there is a pressing…

Noise can be considered the natural enemy of quantum information. An often implied benefit of high-dimensional entanglement is its increased resilience to noise. However, manifesting this potential in an experimentally meaningful fashion is…

We establish that, in an appropriate limit, qubits of communication should be regarded as composite resources, decomposing cleanly into independent correlation and transmission components. Because qubits of communication can establish ebits…

Quantum Physics · Physics 2020-08-12 Patrick Hayden , Geoffrey Penington

We study the capacity of d-dimensional quantum channels with memory modeled by correlated noise. We show that, in agreement with previous results on Pauli qubit channels, there are situations where maximally entangled input states achieve…

Quantum Physics · Physics 2007-05-23 E. Karpov , D. Daems , N. J. Cerf

Quantum capacity quantifies the amount of quantum information that can be transmitted by a quantum channel with an arbitrary small probability of error. Mathematically, the quantum capacity is given by an asymptotic formula involving the…

Quantum Physics · Physics 2025-12-30 Zhen Wu , Zhihao Ma , James Fullwood

Quantum entanglement is a crucial resource for learning properties from nature, but a precise characterization of its advantage can be challenging. In this work, we consider learning algorithms without entanglement to be those that only…

Quantum Physics · Physics 2024-10-21 Senrui Chen , Changhun Oh , Sisi Zhou , Hsin-Yuan Huang , Liang Jiang

High-dimensional entanglement promises to greatly enhance the performance of quantum communication and enable quantum advantages unreachable by qubit entanglement. One of the great challenges, however, is the reliable production,…

Quantum entanglement, a fundamental property ensuring security of key distribution and efficiency of quantum computing, is extremely sensitive to decoherence. Different procedures have been developed in order to recover entanglement after…

Quantum Physics · Physics 2008-04-23 Fabio Sciarrino , Eleonora Nagali , Francesco De Martini , Miroslav Gavenda , Radim Filip

The entanglement cost of a quantum channel is the minimal rate at which entanglement (between sender and receiver) is needed in order to simulate many copies of a quantum channel in the presence of free classical communication. In this…

Quantum Physics · Physics 2015-11-03 Mario Berta , Fernando Brandao , Matthias Christandl , Stephanie Wehner