scholarly journals Efficient verification of entangled continuous-variable quantum states with local measurements

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Ye-Chao Liu ◽  
Jiangwei Shang ◽  
Xiangdong Zhang
Keyword(s):  
Continuous Variable ◽  
Quantum States ◽  
Local Measurements ◽  
Efficient Verification

Quantum dialogue protocol with four-mode continuous variable GHZ state

2019 ◽  
Vol 33 (05) ◽  
pp. 1950033 ◽  
Author(s):  
Ming-Hui Zhang ◽  
Jin-Ye Peng ◽  
Zheng-Wen Cao
Keyword(s):  
Channel Capacity ◽  
Quantum Channel ◽  
Beam Splitter ◽  
Information Leakage ◽  
Continuous Variable ◽  
Ghz State ◽  
Quantum States ◽  
Quantum Dialogue ◽  
Discrete Variable ◽  
Secret Information

Quantum dialogue can realize the mutual transmission of secret information between two legal users. In most of the existing quantum dialogue protocols, the information carriers applied in quantum dialogue are discrete variable (DV) quantum states. However, there are certain limitations on the preparation and detection of DV quantum states with current techniques. Continuous variable (CV) quantum states can overcome these problems effectively while improving the quantum channel capacity. In this paper, we propose a quantum dialogue protocol with four-mode continuous variable GHZ state. Compared with the existing CV-based quantum dialogue protocols, the protocol allows two users to transmit two groups of secret information with different lengths to each other simultaneously. The channel capacity of the protocol has been improved as each traveling mode carries two- or four-bits of information. In addition, the protocol has been proved to be secure against information leakage problem and some common attacks, such as beam splitter attack and intercept-and-resend attack.

A method for efficiently estimating non-Gaussianity of continuous-variable quantum states

2020 ◽  
Vol 74 (1) ◽  
Author(s):  
Shao-Hua Xiang ◽  
Yu-Jing Zhao ◽  
Cheng Xiang ◽  
Wei Wen ◽  
Xue-Wen Long
Keyword(s):  
Continuous Variable ◽  
Quantum States

TELEPORTATION OF ANY FORM OF SINGLE-MODE QUANTUM STATES

2006 ◽  
Vol 20 (02n03) ◽  
pp. 97-103
Author(s):  
TONG-QIANG SONG
Keyword(s):  
Quantum Channel ◽  
Quantum Teleportation ◽  
Single Mode ◽  
Continuous Variable ◽  
Quantum States ◽  
Squeezed Vacuum ◽  
Einstein Podolsky Rosen ◽  
Epr Pair

By using the two-mode Einstein–Podolsky–Rosen (EPR) pair eigenstates or the two-mode squeezed vacuum as quantum channel we study the quantum teleportation of any form of single-mode quantum states (which include discrete and continuous variable quantum states). The elegant properties of the EPR pair eigenstates bring much convenience to our discussion.

scholarly journals About the use of fidelity in continuous variable systems

2014 ◽  
Vol 12 (02) ◽  
pp. 1461015 ◽  
Author(s):  
Antonio Mandarino ◽  
Matteo Bina ◽  
Stefano Olivares ◽  
Matteo G. A. Paris
Keyword(s):  
Physical Properties ◽  
Continuous Variable ◽  
Quantum States ◽  
High Fidelity ◽  
Non Gaussian ◽  
Additional Constraints

We present examples of continuous variable (CV) states having high fidelity to a given target, say F > 0.9 or F > 0.99, and still showing striking differences in their physical properties, including classical and quantum states within the set, separable and entangled ones, or nearly Gaussian and strongly non-Gaussian ones. We also show that the phenomenon persists also when one imposes additional constraints on the energy or the squeezing fraction of the states, thus generally questioning the use of fidelity to assess properties of CV systems without a tomographic set of additional constraints.

scholarly journals Direct Measurement of Nonlinear Properties of Bipartite Quantum States

2006 ◽  
Vol 13 (03) ◽  
pp. 281-289
Author(s):  
F. A. Bovino ◽  
G. Castagnoli ◽  
A. Ekert ◽  
C. Moura Alves ◽  
P. Horodecki ◽  
...  
Keyword(s):  
Information Science ◽  
Quantum States ◽  
Full Description ◽  
Entangled Photons ◽  
Entanglement Witness ◽  
Entropic Inequalities ◽  
Nonlinear Properties ◽  
Local Measurements ◽  
Marking Technique ◽  
Chsh Inequalities

Nonlinear properties of quantum states, such as entropy or entanglement, quantify important physical resources and are frequently used in quantum information science. They are usually calculated from a full description of a quantum state, even though they depend only on a small number of parameters that specify the state. Here we extract a nonlocal and a nonlinear quantity, namely the Renyi entropy, from local measurements on two pairs of polarization entangled photons. We also introduce a "phase marking" technique which allows to select uncorrupted outcomes even with nondeterministic sources of entangled photons. We use our experimental data to demonstrate the violation of entropic inequalities. They are examples of a nonlinear entanglement witness and their power exceeds all linear tests for quantum entanglement based on all possible Bell-CHSH inequalities.

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