CONTINUOUS–VARIABLE TELEPORTATION OF SINGLE–PHOTON STATES AND AN ACCIDENTAL CLONING OF A PHOTONIC QUBIT IN TWO–CHANNEL TELEPORTATION

Author(s):  
Toshiki Ide
2001 ◽  
Vol 65 (1) ◽  
Author(s):  
Toshiki Ide ◽  
Holger F. Hofmann ◽  
Takayoshi Kobayashi ◽  
Akira Furusawa

2018 ◽  
Vol 25 (02) ◽  
pp. 1850007 ◽  
Author(s):  
Anita Da̧browska

Using Gardiner and Collet’s input-output model and the concept of cascade system, we determine the filtering equation for a quantum system driven by light in some specific nonclassical states. The quantum system and electromagnetic field are described by making use of quantum stochastic unitary evolution. We consider two examples of the nonclassical states of field: a combination of vacuum and single photon states and a mixture of two coherent states. The stochastic evolution conditioned on the results of the photon counting and quadrature measurements is described.


2021 ◽  
Author(s):  
Matthew Brown ◽  
Valerian Thiel ◽  
Markus Allgaier ◽  
Michael Raymer ◽  
Brian Smith ◽  
...  

Entropy ◽  
2020 ◽  
Vol 22 (5) ◽  
pp. 571
Author(s):  
Yuang Wang ◽  
Shanhua Zou ◽  
Yun Mao ◽  
Ying Guo

Underwater quantumkey distribution (QKD) is tough but important formodern underwater communications in an insecure environment. It can guarantee secure underwater communication between submarines and enhance safety for critical network nodes. To enhance the performance of continuous-variable quantumkey distribution (CVQKD) underwater in terms ofmaximal transmission distance and secret key rate as well, we adopt measurement-device-independent (MDI) quantum key distribution with the zero-photon catalysis (ZPC) performed at the emitter of one side, which is the ZPC-based MDI-CVQKD. Numerical simulation shows that the ZPC-involved scheme, which is a Gaussian operation in essence, works better than the single photon subtraction (SPS)-involved scheme in the extreme asymmetric case. We find that the transmission of the ZPC-involved scheme is longer than that of the SPS-involved scheme. In addition, we consider the effects of temperature, salinity and solar elevation angle on the system performance in pure seawater. The maximal transmission distance decreases with the increase of temperature and the decrease of sunlight elevation angle, while it changes little over a broad range of salinity


1998 ◽  
Vol 07 (01) ◽  
pp. 121-130 ◽  
Author(s):  
F. de Martini ◽  
O. Jedrkiewicz ◽  
P. Mataloni

The process of generation of non-classical radiation in an active Fabry-Perot dye microcavity, under femtosecond excitation, has been investigated. Single photon states, with a non-classical sub-Poissonian distribution have been generated after the excitation of a small number of active molecules, located between the two mirrors. By multiple excitation of the active medium, collective emission phenomena are expected because of the strong superradiant coupling occurring within the transverse coherence area of the microcavity. In particular, we have experimentally verified the principle of relativistic causality within the process of two-dipole superradiance by transverse interaction, in condition of strong microcavity confinement.


Author(s):  
G. Harder ◽  
V. Ansari ◽  
T. J. Bartley ◽  
B. Brecht ◽  
C. Silberhorn

In the last few decades, there has been much progress on low loss waveguides, very efficient photon-number detectors and nonlinear processes. Engineered sum-frequency conversion is now at a stage where it allows operation on arbitrary temporal broadband modes, thus making the spectral degree of freedom accessible for information coding. Hereby the information is often encoded into the temporal modes of a single photon. Here, we analyse the prospect of using multi-photon states or squeezed states in different temporal modes based on integrated optics devices. We describe an analogy between mode-selective sum-frequency conversion and a network of spatial beam splitters. Furthermore, we analyse the limits on the achievable squeezing in waveguides with current technology and the loss limits in the conversion process. This article is part of the themed issue ‘Quantum technology for the 21st century’.


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