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A new paradigm is proposed for the robustification of the LQG controller against distributional uncertainties on the noise process. Our controller optimizes the closed-loop performances in the worst possible scenario under the constraint…

Systems and Control · Electrical Eng. & Systems 2024-09-18 Lucia Falconi , Augusto Ferrante , Mattia Zorzi

Entanglement distillation is a key primitive for distributing high-quality entanglement between remote locations. Probabilistic noiseless linear amplification based on the quantum scissors is a candidate for entanglement distillation from…

Quantum Physics · Physics 2019-08-15 Kaushik P. Seshadreesan , Hari Krovi , Saikat Guha

Noisy unsharp measurements incorporated in quantum information protocols may hinder performance, reducing the quantum advantage. However, we show that, unlike projective measurements which completely destroy quantum correlations between…

Quantum Physics · Physics 2025-07-01 Sudipta Mondal , Pritam Halder , Amit Kumar Pal , Aditi Sen De

Free-space quantum cryptography has the potential to enable global quantum communication. However, most existing continuous-variable quantum secret sharing (CV-QSS) schemes rely on fiber channels. In this paper, we present a CV-QSS protocol…

Quantum Physics · Physics 2025-03-17 Fangli Yang , Liang Chang , Daowen Qiu , Minghua Pan , Wanjun Xiong

The purpose of a phase-preserving linear amplifier is to make a small signal larger, regardless of its phase, so that it can be perceived by instruments incapable of resolving the original signal, while sacrificing as little as possible in…

Quantum Physics · Physics 2013-03-26 Carlton M. Caves , Joshua Combes , Zhang Jiang , Shashank Pandey

Estimation of channel parameters is important for extending the range and increasing the key rate of continuous variable quantum key distribution protocols. We propose a new estimator for the channel noise parameter based on the method of…

Quantum Physics · Physics 2016-05-04 Oliver Thearle , Syed M. Assad , Thomas Symul

In quantum communication via noisy channels, the error probability scales exponentially with the length of the channel. We present a scheme of a quantum repeater that overcomes this limitation. The central idea is to connect a string of…

Quantum Physics · Physics 2007-05-23 H. -J. Briegel , W. Dür , J. I. Cirac , P. Zoller

We report a continuous variable key distribution system that achieves a final secure key rate of 3.45 kb/sec over a distance of 24.2 km of optical fiber. The protocol uses discrete signaling and post-selection to improve reconciliation…

Quantum Physics · Physics 2009-10-07 Quyen Dinh Xuan , Zheshen Zhang , Paul L. Voss

We propose and theoretically analyze a teleportation-based scheme for high-fidelity noiseless quantum amplification of coherent states of light. In our approach, the probabilistic noiseless quantum amplification operation is encoded into a…

Quantum Physics · Physics 2025-08-26 Jaromír Fiurášek

We investigate quantum key distribution (QKD) in optical multiple-input-multiple-output (MIMO) settings. Such settings can prove useful in dealing with harsh channel conditions as in, e.g., satellite-based QKD. We study a $2\times2$ setting…

Quantum Physics · Physics 2023-08-23 Shradhanjali Sahu , Ahmed Lawey , Mohsen Razavi

Quantum key distribution can be enhanced and extended if nonclassical single-photon states of light are used. We study a connection between the security of quantum key distribution and quantum non-Gaussianity of light arriving at the…

Quantum Physics · Physics 2017-07-13 Mikołaj Lasota , Radim Filip , Vladyslav C. Usenko

We address side-channel leakage in a trusted preparation station of continuous-variable quantum key distribution with coherent and squeezed states. We consider two different scenaria: multimode Gaussian modulation, directly accessible to an…

Quantum Physics · Physics 2017-12-13 Ivan Derkach , Vladyslav C. Usenko , Radim Filip

Conventional computers have evolved to device components that demonstrate failure rates of 1e-17 or less, while current quantum computing devices typically exhibit error rates of 1e-2 or greater. This raises concerns about the reliability…

Quantum Physics · Physics 2022-11-02 Samudra Dasgupta , Travis S. Humble

In this paper, using the full security framework for continuous variable quantum key distribution (CV-QKD), we provide a composable security proof for the CV-QKD system in a realistic implementation. We take into account equipment losses…

Quantum Physics · Physics 2022-09-19 Roman Goncharov , Alexei D. Kiselev , Eduard Samsonov , Vladimir Egorov

Surface plasmon polariton amplification gives the possibility to overcome strong absorption in the metal and design truly nanoscale devices for on-chip photonic circuits. However, the process of stimulated emission in the gain medium is…

Optics · Physics 2019-04-29 Andrey A. Vyshnevyy , Dmitry Yu. Fedyanin

The impressive progress in quantum hardware in the last years has raised the interest of the quantum computing community in harvesting the computational power of such devices. However, in the absence of error correction, these devices can…

Quantum Physics · Physics 2023-02-21 Giacomo De Palma , Milad Marvian , Cambyse Rouzé , Daniel Stilck França

Many different quantum information communication protocols such as teleportation, dense coding and entanglement based quantum key distribution are based on the faithful transmission of entanglement between distant location in an optical…

A noisy Gaussian channel is defined as a channel in which an input field mode is subjected to random Gaussian displacements in phase space. We introduce the quantum fidelity of a Gaussian channel for pure and mixed input states, and we…

Quantum Physics · Physics 2007-05-23 Carlton M. Caves , Krzysztof Wodkiewicz

This paper presents a method of cryptographic key distribution using an `artificially' noisy channel. This is an important development because, while it is known that a noisy channel can be used to generate unconditional secrecy, there are…

Information Theory · Computer Science 2012-12-04 Benjamin T. H. Varcoe

We address the characterization of dissipative bosonic channels and show that estimation of the loss rate by Gaussian probes (coherent or squeezed) is improved in the presence of Kerr nonlinearity. In particular, enhancement of precision…

Quantum Physics · Physics 2016-05-11 Matteo A. C. Rossi , Francesco Albarelli , Matteo G. A. Paris