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Excess noise is a major obstacle to high-performance continuous-variable quantum key distribution (CVQKD), which is mainly derived from the amplitude attenuation and phase fluctuation of quantum signals caused by channel instability. Here,…

Quantum Physics · Physics 2022-07-22 Kexin Liang , Geng Chai , Zhengwen Cao , Qing Wang , Lei Wang , Jinye Peng

The capacity of multiple-input multiple-output additive white Gaussian noise channels is investigated under peak amplitude constraints on the norm of the input vector. New insights on the capacity-achieving input distribution are presented.…

Information Theory · Computer Science 2021-05-06 Antonino Favano , Marco Ferrari , Maurizio Magarini , Luca Barletta

We review recent results on the simulation of quantum channels, the reduction of adaptive protocols (teleportation stretching), and the derivation of converse bounds for quantum and private communication, as established in PLOB [Pirandola,…

Prior entanglement between sender and receiver, which exactly doubles the classical capacity of a noiseless quantum channel, can increase the classical capacity of some noisy quantum channels by an arbitrarily large constant factor…

Quantum Physics · Physics 2009-01-23 Charles H. Bennett , Peter W. Shor , John A. Smolin , Ashish V. Thapliyal

As with classical information, error-correcting codes enable reliable transmission of quantum information through noisy or lossy channels. In contrast to the classical theory, imperfect quantum channels exhibit a strong kind of synergy:…

Quantum Physics · Physics 2013-02-05 Graeme Smith , John A. Smolin , Jon Yard

Using random Gaussian vectors and an information-uncertainty relation, we give a proof that the coherent information is an achievable rate for entanglement transmission through a noisy quantum channel. The codes are random subspaces…

Quantum Physics · Physics 2012-07-06 Patrick Hayden , Peter W. Shor , Andreas Winter

An additive noise channel is considered, in which the distribution of the noise is nonparametric and unknown. The problem of learning encoders and decoders based on noise samples is considered. For uncoded communication systems, the problem…

Information Theory · Computer Science 2021-11-17 Nir Weinberger

We address the role of the phase-insensitive trusted preparation and detection noise in the security of a continuous-variable quantum key distribution, considering the Gaussian protocols on the basis of coherent and squeezed states and…

Quantum Physics · Physics 2016-01-14 Vladyslav C. Usenko , Radim Filip

Recent outer bounds on the capacity region of Gaussian interference channels are generalized to $m$-user channels with $m>2$ and asymmetric powers and crosstalk coefficients. The bounds are again shown to give the sum-rate capacity for…

Information Theory · Computer Science 2008-01-16 Xiaohu Shang , Gerhard Kramer , Biao Chen

We describe two quantum channels that individually cannot send any information, even classical, without some chance of decoding error. But together a single use of each channel can send quantum information perfectly reliably. This proves…

Quantum Physics · Physics 2011-12-19 Jianxin Chen , Toby S. Cubitt , Aram W. Harrow , Graeme Smith

Maximally entangled states--a resource for quantum information processing--can only be shared through noiseless quantum channels, whereas in practice channels are noisy. Here we ask: Given a noisy quantum channel, what is the maximum…

Quantum Physics · Physics 2018-07-17 Rajarshi Pal , Somshubhro Bandyopadhyay , Sibasish Ghosh

Entanglement and entanglement-assisted are useful resources to enhance the mutual information of the Pauli channels, when the noise on consecutive uses of the channel has some partial correlations. In this Paper, we study…

Quantum Physics · Physics 2015-06-26 A. Fahmi , M. Golshani

Dephasing is a prominent noise mechanism that afflicts quantum information carriers, and it is one of the main challenges towards realizing useful quantum computation, communication, and sensing. Here we consider discrimination and…

Quantum Physics · Physics 2024-06-11 Zixin Huang , Ludovico Lami , Mark M. Wilde

The threshold theorem is a fundamental result in the theory of fault-tolerant quantum computation stating that arbitrarily long quantum computations can be performed with a polylogarithmic overhead provided the noise level is below a…

Quantum Physics · Physics 2024-03-15 Omar Fawzi , Alexander Müller-Hermes , Ala Shayeghi

Entanglement is a unique resource for quantum-enhanced applications. When employed in sensing, shared entanglement between distributed quantum sensors enables a substantial gain in the measurement sensitivity in estimating global parameters…

Quantum Physics · Physics 2019-01-23 Yi Xia , Quntao Zhuang , William Clark , Zheshen Zhang

We present an effcient experimental procedure that certifies non vanishing quantum capacities for qubit noisy channels. Our method is based on the use of a fixed bipartite entangled state, where the system qubit is sent to the channel…

We provide a versatile upper bound on the number of maximally entangled qubits, or private bits, shared by two parties via a generic adaptive communication protocol over a quantum network when the use of classical communication is not…

Quantum Physics · Physics 2018-01-30 Luca Rigovacca , Go Kato , Stefan Bäuml , M. S. Kim , W. J. Munro , Koji Azuma

Progress in the development of techniques for the construction of multiuser quantum communications networks is reviewed in light of the plans for an EU quantum communications infrastructure (EU QCI). Quantum key distribution networks may be…

Quantum Physics · Physics 2022-01-06 Adam M. Lewis , Petra F. Scudo

It is known that advantage distillation (that is, information reconciliation using two-way communication) improves noise tolerances for quantum key distribution (QKD) setups. Two-way communication is hence also of interest in the…

Quantum Physics · Physics 2023-03-27 Thomas A. Hahn , Ernest Y. -Z. Tan

Quantum communication at microwave frequencies has been fundamentally constrained by the susceptibility of microwave photons to thermal noise, hindering their application in scalable quantum networks. Here we demonstrate a…