7 results on '"Noiseless amplifier"'
Search Results
2. Improving the maximum transmission distance of continuous-variable quantum key distribution using a noiseless amplifier.
- Author
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Blandino, Rémi, Leverrier, Anthony, Barbieri, Marco, Etesse, Jean, Tualle-Brouri, Rosa, and Grangier, Philippe
- Subjects
- *
OPTICAL amplifiers , *QUANTUM optics , *QUANTUM cryptography , *GAUSSIAN channels , *PHASE modulation - Abstract
We show that the maximum transmission distance of continuous-variable quantum key distribution in presence of a Gaussian noisy lossy channel can be arbitrarily increased using a heralded noiseless linear amplifier. We explicitly consider a protocol using amplitude and phase modulated coherent states with reverse reconciliation. Assuming that the secret key rate drops to zero for a line transmittance Tlim, we find that a noiseless amplifier with amplitude gain g can improve this value to Tlim/g², corresponding to an increase in distance proportional to logg. We also show that the tolerance against noise is increased. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
3. Novel matched amplifiers with low noise positive feedback. Part II: Resistive-capacitive feedback.
- Author
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Bruck, Y. and Zakharenko, V.
- Subjects
- *
ELECTRONIC amplifiers , *ELECTRONIC feedback , *ELECTRIC circuits , *ELECTRIC resistance , *ELECTRONICS - Abstract
This article is a continuation of consideration for an amplifier with resistive positive feedback (RPF) (Bruck (2008), 'Novel Matched LNA with Low Noise Positive Feedback. Part 1: General Features and Resistive Feedback', International Journal of Electronics, 95, 441-456). We propose here new configuration schematics of a transformer-less selective LNA with resistive-capacitive positive feedback (RCPF). A circuit of an amplifier with a transistor connected into a circuit with a common base (CB) configuration is analysed in detail. RCPF and RPF circuits are compared. It is shown that the LNA RCPF provides any pass-band, a good level of input and output matching, a minimum noise temperature which is significantly lower than that of the LNA RPF, a rather high linearity, and stability of amplification. The simulation results and some experimental data for the amplifiers intended for use in the LOFAR radiotelescope (Konovalenko et al. (2003), 'Thirty Element Array Antenna as a Prototype of a Huge Low-Frequency Radio Telescope,' Experimental Astronomy, 16, 149-164; Konovalenko (2007), 'Ukrainian Contribution to LOFAR', A scientific workshop, organised by LOFAR/ASTRON' Emmen, Netherlands, 23-27. http://www.lofar.org/workshop) are given. It is assumed that such devices are of a special interest for high-frequency integral circuits (IC). [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
4. Novel matched amplifiees with low noise positive feedback. Part 1: General features and resistive feedback.
- Author
-
Bruck, Y.
- Subjects
- *
BROADBAND amplifiers , *INTEGRATED circuits , *ELECTRONIC amplifiers , *TRANSISTORS , *PATENTS - Abstract
The prominent inventions of D.E. Norton as well as other similar schematics are widely used in different circuits of amplifiers and mixers. However, the use of these circuits in high-frequency integrated circuits (IC) is still hindered by the presence of the broadband feedback transformer. We propose new configuration schematics of transformer-less amplifiers with similar properties. Now we understand implicitly that this opportunity was already contained in our previous patents and papers. Here, the generalised circuit of an amplifier with a complex positive current feedback and with a common base (CB) transistor configuration is considered. Besides, the circuit of low noise amplifier (LNA) with a resistive positive feedback (RPF) is investigated in detail. RPF and CB amplifiers are compared. It is demonstrated that LNA RPF provides gain stability vs scattering of parameters, a good level of the input and output matching, a wider frequency band and the noise temperature more than twice as low as that in CB and, despite a positive feedback, it provides a high stability gain. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
5. Entanglement of mesoscopic quantum fields for quantum communications
- Author
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Blandino, Rémi, Laboratoire Charles Fabry / Optique Quantique, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), Université Paris Sud - Paris XI, and Rosa Tualle-Brouri
- Subjects
Quantum correlations ,Quantum optics ,Non-Gaussian states ,Discorde quantique ,Quantum information ,Noiseless amplifier ,Amplificateur sans bruit ,Information quantique ,Quantum discord ,États non-gaussiens ,[PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other] ,Continuous variables ,Variables continues ,Corrélations quantiques ,Optique quantique - Abstract
This thesis is concerned with different aspects of quantum information with the continuous variables of quantum states of light. Through the combination of the continuous and discrete descriptions, where the light is either described in terms of quadratures or photons, non-classical quantum states and elementary quantum information protocols have been theoretically studied and experimentally implemented. We have experimentally implemented a quantum superposition of two quasi-classical states of light, a “Schrödinger cat state”, which was used to feed a quantum phase gate. We have analysed the quality of this implementation by using a simple model of the experiment. We have then studied quantum correlations, as captured by the quantum discord, for an important class of states in quantum information. We have compared the precision of our measurements by using the classical and quantum Cramér-Rao bounds. Finally, we have theoretically studied the use of a non-deterministic quantum amplifier in quantum cryptography. This amplifier has the property to amplify quantum states without amplifying their quantum noise. Using this property, we have shown that it is possible to increase the maximum distance of transmission of a secret key, as well as the tolerance to the noise added by the quantum channel.; Cette thèse s’inscrit dans le cadre de l’information quantique avec des variables continues, en utilisant des états quantiques du champ électromagnétique. En combinant les outils propres aux variables discrètes, o`u la lumière est décrite en termes de photons, avec les outils des variables continues, où la lumière est décrite en termes de quadratures, nous pouvons étudier théoriquement et produire expérimentalement des états non-classiques, ainsi que des protocoles élémentaires d’information quantique. Ainsi, nous avons produit expérimentalement un état «chat de Schrödinger», superposition quantique de deux états lumineux quasi-classiques, sur lequel nous avons appliqué une porte quantique introduisant une phase dans la superposition. Nous avons ensuite analysé la qualité de cette porte en utilisant un modèle simple de notre expérience. Nous nous sommes ensuite intéressés aux corrélations quantiques, mesurées par la discorde quantique, pour une classe d’états particulièrement importants en information quantique. Nous avons quantifié la précision de nos mesures en les comparant aux bornes de Cramér-Rao classique et quantique. Enfin, nous avons étudié théoriquement l’utilisation d’un amplificateur quantique non-déterministe en cryptographie quantique. Cet amplificateur possède la propriété de pouvoir amplifier des états quantiques sans en amplifier le bruit quantique associé. Ainsi, nous avons montré qu’il permet une amélioration de la distance maximale de transmission d’une clé secrète, ainsi qu’une amélioration de la résistance au bruit introduit par le canal quantique.
- Published
- 2013
6. Intrication de champs quantiques mesoscopiques pour les communications quantiques
- Author
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Blandino, Rémi, Laboratoire Charles Fabry / Optique Quantique, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), Université Paris Sud - Paris XI, and Rosa Tualle-Brouri
- Subjects
Quantum correlations ,Quantum optics ,Non-Gaussian states ,Discorde quantique ,Quantum information ,Noiseless amplifier ,Amplificateur sans bruit ,Information quantique ,Quantum discord ,États non-gaussiens ,[PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other] ,Continuous variables ,Variables continues ,Corrélations quantiques ,Optique quantique - Abstract
This thesis is concerned with different aspects of quantum information with the continuous variables of quantum states of light. Through the combination of the continuous and discrete descriptions, where the light is either described in terms of quadratures or photons, non-classical quantum states and elementary quantum information protocols have been theoretically studied and experimentally implemented. We have experimentally implemented a quantum superposition of two quasi-classical states of light, a “Schrödinger cat state”, which was used to feed a quantum phase gate. We have analysed the quality of this implementation by using a simple model of the experiment. We have then studied quantum correlations, as captured by the quantum discord, for an important class of states in quantum information. We have compared the precision of our measurements by using the classical and quantum Cramér-Rao bounds. Finally, we have theoretically studied the use of a non-deterministic quantum amplifier in quantum cryptography. This amplifier has the property to amplify quantum states without amplifying their quantum noise. Using this property, we have shown that it is possible to increase the maximum distance of transmission of a secret key, as well as the tolerance to the noise added by the quantum channel.; Cette thèse s’inscrit dans le cadre de l’information quantique avec des variables continues, en utilisant des états quantiques du champ électromagnétique. En combinant les outils propres aux variables discrètes, o`u la lumière est décrite en termes de photons, avec les outils des variables continues, où la lumière est décrite en termes de quadratures, nous pouvons étudier théoriquement et produire expérimentalement des états non-classiques, ainsi que des protocoles élémentaires d’information quantique. Ainsi, nous avons produit expérimentalement un état «chat de Schrödinger», superposition quantique de deux états lumineux quasi-classiques, sur lequel nous avons appliqué une porte quantique introduisant une phase dans la superposition. Nous avons ensuite analysé la qualité de cette porte en utilisant un modèle simple de notre expérience. Nous nous sommes ensuite intéressés aux corrélations quantiques, mesurées par la discorde quantique, pour une classe d’états particulièrement importants en information quantique. Nous avons quantifié la précision de nos mesures en les comparant aux bornes de Cramér-Rao classique et quantique. Enfin, nous avons étudié théoriquement l’utilisation d’un amplificateur quantique non-déterministe en cryptographie quantique. Cet amplificateur possède la propriété de pouvoir amplifier des états quantiques sans en amplifier le bruit quantique associé. Ainsi, nous avons montré qu’il permet une amélioration de la distance maximale de transmission d’une clé secrète, ainsi qu’une amélioration de la résistance au bruit introduit par le canal quantique.
- Published
- 2013
7. Discretely modulated continuous-variable quantum key distribution with a nondeterministic noiseless amplifier
- Author
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Jian Fang, Guihua Zeng, Peng Huang, Guangqiang He, Yuan Lu, Fang, Jian, Lu, Yuan, Huang, Peng, He, Guangqiang, and Zeng, Guihua
- Subjects
Physics and Astronomy (miscellaneous) ,Computer science ,CV-QKD ,noiseless amplifier ,Amplifier ,Gaussian ,Quantum key distribution ,Topology ,Noise (electronics) ,discrete modulation ,Nondeterministic algorithm ,symbols.namesake ,Transmission (telecommunications) ,Modulation ,symbols ,Linear amplifier - Abstract
In this paper, we first study a generalized protocol of discrete modulation for continuous-variable quantum key distribution with N coherent states in a Gaussian lossy and noisy channel and investigate its performance against collective attacks. We find that discrete modulation protocols with more than eight states do not perform better than the eight-state protocol. Then, we study the improvement of this protocol by using a nondeterministic noiseless linear amplifier (NLA) on Bob's detection stage. Results indicate that a NLA with gain g can extend the maximum transmission distance by 50 log10g2km and can increase the maximal tolerable excess noise. With the reconciliation efficiency β, we find the gain of NLA has a maximal value defined as gmaxand by adjusting the gain to about βgmaxone can have the best improvement on secret key rate.
- Published
- 2013
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