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We address the role of noisy squeezing in security and performance of continuous-variable (CV) quantum key distribution (QKD) protocols. Squeezing has long been recognized for its numerous advantages in CV QKD, such as enhanced robustness…

Quantum Physics · Physics 2025-03-10 Akash nag Oruganti , Ivan Derkach , Radim Filip , Vladyslav C. Usenko

We investigate all possible noise environments for controlled remote state preparation. We find that the optimal efficiency is not only dependent on the isolate decay rate but also dependent on the coupling term of environments. Such a…

Quantum Physics · Physics 2016-04-06 Yuan-hua Li , Zisheng Wang , Hua-qing Zhou , Xian-feng Chen

Security of a continuous-variable quantum key distribution protocol based on noisy coherent states and channel is analyzed. Assuming the noise of coherent states is induced by Fred, a neutral party relative to others, we prove that the…

Quantum Physics · Physics 2015-05-13 Yong Shen , Jian Yang , Hong Guo

We show that for some noisy channels, the optimal entanglement-assisted strategy depends on the noise level. We note that there is a non-trivial crossover between the parallel-entangled strategy and the ancilla-assisted strategy - in the…

Quantum Physics · Physics 2018-03-28 Zixin Huang , Chiara Macchiavello , Lorenzo Maccone

We present a novel scheme for controlled quantum secure communication (CQSC) using GHZ-like state. In this scheme, a trusted controller assists the users for achieving secure transmission of data between them. The dense coding technique is…

Quantum Physics · Physics 2016-07-27 Jemy Geordy , Dintomon Joy , M Sabir

The four quantum noises Bit Flip, Phase Flip, Depolarization, and Amplitude Damping as well as any potential combinations of them are examined in this papers investigation of quantum teleportation using qutrit states. Among the above…

Quantum Physics · Physics 2023-09-22 Arun Sebastian , Afnan. N. Mansar , N. C. Randeep

To establish an entangled state of optimal fidelity between two distant observers when the available quantum channel is noisy, is a central problem in quantum information theory. We consider an instance of this problem for two-qubit systems…

Quantum Physics · Physics 2012-09-18 Somshubhro Bandyopadhyay , Anindita Ghosh

For parameter estimation from an $N$-component composite quantum system, it is known that a separable preparation leads to a mean-squared estimation error scaling as $1/N$ while an entangled preparation can in some conditions afford a…

Quantum Physics · Physics 2019-04-04 Francois Chapeau-Blondeau

Noise in entangled quantum systems is difficult to characterize due to many-body effects involving multiple degrees of freedom. This noise poses a challenge to quantum computing, where two-qubit gate performance is critical. Here, we…

We consider whether quantum coherence in the form of mutual entanglement between a pair of qubits is susceptible to decay that may be more rapid than the decay of the coherence of either qubit individually. An instance of potential…

Quantum Physics · Physics 2009-11-10 Ting Yu , J. H. Eberly

Decoy state protocols are a useful tool for many quantum key distribution systems implemented with weak coherent pulses, allowing significantly better secret bit rates and longer maximum distances. In this paper we present a method to…

Quantum Physics · Physics 2009-01-23 Patrick Rice , Jim Harrington

We present a scheme for quantum secure direct communication with quantum encryption. The two authorized users use repeatedly a sequence of the pure entangled pairs (quantum key) shared for encrypting and decrypting the secret message…

Quantum Physics · Physics 2007-07-31 Xi-Han Li , Chun-Yan Li , Fu-Guo Deng , Ping Zhou , Yu-Jie Liang , Hong-Yu Zhou

Quantum state purification protocols, which mitigate noise by converting multiple copies of noisy quantum states into fewer copies with a lower noise level, have applications in quantum communication and computation with imperfect devices.…

Quantum Physics · Physics 2026-03-10 Benchi Zhao , Yu-Ao Chen , Xuanqiang Zhao , Chengkai Zhu , Giulio Chiribella , Xin Wang

Decoy states have recently been proposed as a useful method for substantially improving the performance of quantum key distribution. Here, we present a general theory of the decoy state protocol based on only two decoy states and one signal…

Quantum Physics · Physics 2009-11-11 X. Ma , B. Qi , Y. Zhao , H. -K. Lo

With the advent of quantum cloud computing, the security of delegated quantum computation has become of utmost importance. While multiple statistically secure blind verification schemes in the prepare-and-send model have been proposed, none…

Quantum Physics · Physics 2026-04-16 Theodoros Kapourniotis , Dominik Leichtle , Luka Music , Harold Ollivier

Transmitting unknown quantum states to distant locations is crucial for distributed quantum information protocols. The seminal quantum teleportation scheme achieves this feat while requiring prior maximal entanglement between the sender and…

Quantum Physics · Physics 2025-04-25 Arkaprabha Ghosal , Jatin Ghai , Tanmay Saha , Sibasish Ghosh , Mir Alimuddin

There has been tremendous progress in the physical realization of quantum computing hardware in recent times, bringing us closer than ever before to realizing the promise of quantum computing. However, noise continues to pose a crucial…

We extend covert communication to the quantum regime by showing that covert quantum communication is possible over optical channels with noise arising either from the environment or from the sender's lab. In particular, we show that…

Quantum Physics · Physics 2016-12-21 Juan Miguel Arrazola , Valerio Scarani

We present a new technique for proving the security of quantum key distribution (QKD) protocols. It is based on direct information-theoretic arguments and thus also applies if no equivalent entanglement purification scheme can be found.…

Quantum Physics · Physics 2009-11-11 R. Renner , N. Gisin , B. Kraus

The safety of a quantum key distribution system relies on the fact that any eavesdropping attempt on the quantum channel creates errors in the transmission. For a given error rate, the amount of information that may have leaked to the…

Quantum Physics · Physics 2009-10-28 B. Huttner , N. Imoto , N. Gisin , T. Mor
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