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We show that no source encoding is needed in the definition of the capacity of a quantum channel for carrying quantum information. This allows us to use the coherent information maximized over all sources and and block sizes, but not…

Quantum Physics · Physics 2011-07-19 H. Barnum , J. A. Smolin , B. M. Terhal

We investigate the classical capacity of two quantum channels with memory: a periodic channel with depolarizing channel branches, and a convex combination of depolarizing channels. We prove that the capacity is additive in both cases. As a…

Quantum Physics · Physics 2009-11-13 Tony Dorlas , Ciara Morgan

Dense coding is arguably the protocol that launched the field of quantum communication. Today, however, more than a decade after its initial experimental realization, the channel capacity remains fundamentally limited as conceived for…

Quantum Physics · Physics 2010-09-28 Julio T. Barreiro , Tzu-Chieh Wei , Paul G. Kwiat

The set of doubly-stochastic quantum channels and its subset of mixtures of unitaries are investigated. We provide a detailed analysis of their structure together with computable criteria for the separation of the two sets. When applied to…

Quantum Physics · Physics 2014-07-30 Christian B. Mendl , Michael M. Wolf

We construct a new entanglement-assisted quantum polar coding scheme which achieves the symmetric coherent information rate by synthesizing "amplitude" and "phase" channels from a given, arbitrary quantum channel. We first demonstrate the…

Quantum Physics · Physics 2012-09-04 Mark M. Wilde , Joseph M. Renes

Channel polarization, originally proposed for binary-input channels, is generalized to arbitrary discrete memoryless channels. Specifically, it is shown that when the input alphabet size is a prime number, a similar construction to that for…

Information Theory · Computer Science 2009-08-04 Eren Sasoglu , Emre Telatar , Erdal Arikan

Random (mixed) unitary channels describe an important subset of quantum channels, which are commonly used in quantum information, noise modeling, and quantum error mitigation. Despite their usefulness, there is substantial complexity in…

Quantum Physics · Physics 2025-01-30 Scott E. Smart , Alexander Jürgens , Joseph Peetz , Prineha Narang

Superdense Coding is a cornerstone in secure quantum communication, exploiting pre-shared entanglement to encode two classical bits within a single qubit. However, noise and decoherence deteriorate entanglement quality, restricting both…

Quantum Physics · Physics 2025-04-18 Syed Emad Uddin Shubha , Tasnuva Farheen

We investigate the capacity of bosonic quantum channels for the transmission of quantum information. Achievable rates are determined from measurable moments of the channel by showing that every channel can asymptotically simulate a Gaussian…

Quantum Physics · Physics 2009-11-13 Michael M. Wolf , David Perez-Garcia , Geza Giedke

The measurement outcomes of two incompatible observables on a particle can be precisely predicted when it is maximally entangled with a quantum memory, as quantified recently [Nature Phys. 6, 659 (2010)]. We explore the behavior of the…

Quantum Physics · Physics 2012-07-26 Z. Y. Xu , W. L. Yang , M. Feng

We calculate the quantum capacity of an amplitude-damping channel with time correlated Markov noise, for two channel uses. Our results show that memory of the channel increases it's ability to transmit quantum information significantly. We…

Quantum Physics · Physics 2017-07-03 Rabia Jahangir , Nigum Arshed , A. H. Toor

We present a scheme of probabilistic dense coding via a quantum channel of non-maximally entangled three-particle state. The quantum dense coding will be succeeded with a certain probability if the sender introduces an auxiliary particle…

Quantum Physics · Physics 2010-02-10 Zhang Guo-Hua , Yan Feng-Li

Using the axiomatic definition of the coherence measure, such as the $l_{1}$ norm and the relative entropy, we study the phenomena of two-qubit system quantum coherence through quantum channels where successive uses of the channels are…

Quantum Physics · Physics 2016-12-30 You-neng Guo , Ke Zeng , Qing-long Tian , Zheng-da Li

Communication over a noisy channel is often conducted in a setting in which different input symbols to the channel incur a certain cost. For example, for bosonic quantum channels, the cost associated with an input state is the number of…

Quantum Physics · Physics 2018-12-27 Dawei Ding , Dmitri S. Pavlichin , Mark M. Wilde

The concept of stochastic resonance in nonlinear dynamics is applied to interpret the capacity of noisy quantum channels. The two-Pauli channel is used to illustrate the idea. The fidelity of the channel is also considered. Noise…

Quantum Physics · Physics 2008-12-18 Julian Juhi-Lian Ting

Quantum superdense coding protocols enhance channel capacity by using shared quantum entanglement between two users. The channel capacity can be as high as 2 when one uses entangled qubits. However, this limit can be surpassed by using…

Quantum Physics · Physics 2019-05-09 Xiao-Min Hu , Yu Guo , Bi-Heng Liu , Yun-Feng Huang , Chuan-Feng Li , Guang-Can Guo

Classical capacity of unital qubit channels is well known, whereas that of nonunital qubit channels is not. We find lower and upper bounds on classical capacity of nonunital qubit channels by using a recently developed decomposition…

Quantum Physics · Physics 2019-03-22 Sergey N. Filippov

We investigate the distributed dense coding (DC) protocol, involving multiple senders and a single or two receivers under the influence of non-Markovian noise, acting on the encoded qubits transmitted from senders to the receiver(s). We…

Quantum Physics · Physics 2024-03-26 Abhishek Muhuri , Rivu Gupta , Srijon Ghosh , Aditi Sen De

We construct concatenated capacity-achieving quantum codes for noisy optical quantum channels. We demonstrate that the error-probability of capacity-achieving quantum polar encoding can be reduced by the proposed low-complexity…

Quantum Physics · Physics 2013-02-14 Laszlo Gyongyosi , Sandor Imre

We consider a network of two nodes separated by a noisy channel with two-sided state information, in which the input and output signals have to be coordinated with the source and its reconstruction. In the case of non-causal encoding and…

Information Theory · Computer Science 2020-09-04 Giulia Cervia , Laura Luzzi , Maël Le Treust , Matthieu R. Bloch