Análise bimodal de teletransporte de estados quânticos da luz no domínio da frequência

Lucas Nunes Faria

Published Dec 9, 2020• 0 citations

Abstract

Two-mode analysis of teleportation of quantum states of light in the frequency domainTransmission of quantum information from one end to another with high fidelity is not a trivial problem.Teleportation presents itself as promising in this regard, by using two communication channels: a classical one -an usual classical communication system -, and a quantum one -built by sharing entangled sources between the involved parties.The first realizations of this procedure worked on a fraction of the performed trials [1, 2], a problem that was solved one year later with a truly unconditional teleportation protocol [3].Since then, better results and different experimental schemes have been developed.The present work encodes information in the frequency modes of light beams, with entanglement between two parties being generated by an above-threshold Optical Parametric Oscillator [4,5,6].The theory for characterizing more general frequency mode states is developed here and presented with experimental results.For the present losses in the system, it is expected a fidelity no better than 42% on the comparison between input and output states without the use of quantum resources.The best measured case with the use of entangled beams resulted in 40% fidelity, close to the threshold of the need for quantum resources but without overcoming it.

DOI: 10.11606/d.43.2020.tde-16122020-135249

Related papers

Teletransporte quântico incondicional de estados de variáveis contínuas de cores distintas: do infravermelho próximo às bandas de telecomunicações

Felipe Lucas Gewers

Quantum teleportation is the basis for numerous quantum applications, with the continuous-variable (CV) protocol having the significant advantage of being unconditional and deterministic, allowing every input state to be teleported. In the context of quantum networks, quantum channels connecting different wavelengths can be used in quantum hybrid technologies, linking different quantum platforms with distinct purposes that interact with light at specific wavelengths. Our approach to building these continuous-variable quantum channels is through quantum teleportation between quadratures of fields at widely different frequencies. To achieve this, we employ a triply resonant optical parametric oscillator (TROPO) operating above threshold as a source of two-mode entangled states. Pumped by a 532 nm Nd:YAG second harmonic laser, the system generates intense beams at 794.4(4) nm (377 THz; near-infrared compatible with the rubidium D1 line) and 1611(3) nm (186 THz; telecommunication L-band), with a frequency separation of 191 THz, which is over one octave. Using the resonator-assisted auto-homodyne technique, we implement the teleportation protocol to transfer a displaced coherent state from the infrared to the telecommunication band. In this work, we report the first demonstration of multi-color continuous-variable (CV) quantum teleportation bridging distinct frequency bands. This also marks the first implementation of teleportation between the sideband modes of intense beams that surpasses the classical fidelity limit. Additionally, we provide the first full characterization of the individual sideband modes in widely separated signal and idler fields generated by an above-threshold optical parametric oscillator. This demonstration paves the way for the development of hybrid quantum systems with enhanced connectivity.

Jun 26, 20250 citations

Two-mode analysis of teleportation of quantum states of light in the frequency domain

Lucas Nunes Faria

A transmissão de informação quântica de uma localidade a outra não é um problema trivial. O teletransporte é uma promessa de solução, um sistema que usa dois canais de comunicação: um clássico --- um sistema usual de transmissão ---, e um quântico - construído pela geração de emaranhamento entre os estados dos usuários envolvidos. As primeiras realizações deste procedimento davam o resultado correto apenas em uma fração das vezes, problema resolvido no ano seguinte no primeiro protocolo de teletransporte incondicional. Desde então, diferentes esquemas experimentais foram sendo implementados e melhores resultados obtidos. O presente trabalho codifica informação nos modos de frequência da luz, com emaranhamento sendo gerado por um Oscilador Paramétrico Ótico acima do limiar. Aqui é desenvolvida a teoria para caracterização de estados em modos de frequência mais gerais, apresentada com os resultados obtidos. Para as perdas existentes no sistema, não é esperado uma fidelidade na comparação entre o estado de saída com o de entrada maior do que 42% sem o uso de recursos quânticos. O melhor resultado obtido com o uso de feixes emaranhados foi de 40%, perto do limiar da necessidade de recursos quânticos mas sem ultrapassá-lo.

Dec 9, 20200 citations

Optimal secure quantum teleportation of coherent states of light

Gerardo Adesso, Pietro Liuzzo-Scorpo

We investigate quantum teleportation of ensembles of coherent states of light with a Gaussian distributed displacement in phase space. Recently, the following general question has been addressed in [P. Liuzzo-Scorpo et al., arXiv:1705.03017]: Given a limited amount of entanglement and mean energy available as resources, what is the maximal fidelity that can be achieved on average in the teleportation of such an alphabet of states? Here, we consider a variation of this question, where Einstein–Podolsky–Rosen steering is used as a resource rather than plain entanglement. We provide a solution by means of an optimisation within the space of Gaussian quantum channels, which allows for an intuitive visualisation of the problem. We first show that not all channels are accessible with a finite degree of steering, and then prove that practical schemes relying on asymmetric two-mode Gaussian states enable one to reach the maximal fidelity at the border with the inaccessible region. Our results provide a rigorous quantitative assessment of steering as a resource for secure quantum teleportation beyond the so-called no-cloning threshold. The schemes we propose can be readily implemented experimentally by a conventional Braunstein–Kimble continuous variable teleportation protocol involving homodyne detections and corrective displacements with an optimally tuned gain. These protocols can be integrated as elementary building blocks in quantum networks, for reliable storage and transmission of quantum optical states.

arXiv:1708.08548Quantum Photonic DevicesAug 29, 20171 citation

Experimental Study of Nonclassical Teleportation Beyond Average Fidelity

Gonzalo Carvacho, Francesco Andreoli, Luca Santodonato +6 more

Quantum teleportation establishes a correspondence between an entangled state shared by two separate parties that can communicate classically and the presence of a quantum channel connecting the two parties. The standard benchmark for quantum teleportation, based on the average fidelity between the input and output states, indicates that some entangled states do not lead to channels which can be certified to be quantum. It was recently shown that if one considers a finer-grained witness, then all entangled states can be certified to produce a nonclassical teleportation channel. Here we experimentally demonstrate a complete characterization of a new family of such witnesses, of the type proposed in Phys. Rev. Lett. 119, 110501 (2017)PRLTAO0031-900710.1103/PhysRevLett.119.110501 under different conditions of noise. We report nonclassical teleportation using quantum states that cannot achieve average fidelity of teleportation above the classical limit. We further use the violation of these witnesses to estimate the negativity of the shared state. Our results have fundamental implications in quantum information protocols and may also lead to new applications and quality certification of quantum technologies.

arXiv:1802.10056Physical Review LettersOct 1, 201812 citations

Activation of entanglement in teleportation

Ryszard Weinar, Wiesław Laskowski, Marcin Pawłowski

We study the activation of entanglement in teleportation protocols. To this end, we a present derivation of the average fidelity of teleportation process with noisy classical channel for qudits. In our work we do not make any assumptions about the entangled states shared by communicating parties. Our result allows us to specify the minimum amount of classical information required to beat the classical limit when the protocol is based on the Bell measurements. We also compare average fidelity of teleportation obtained using noisy and perfect classical channel with restricted capacity. The most important insight into the intricacies of quantum information theory that we gain is that though entanglement, obviously, is a necessary resource for efficient teleportation it requires a certain threshold amount of classical communication to be more useful than classical communication. Another interesting finding is that the amount of classical communication required to activate entanglement for teleportation purposes depends on the dimension d of the system being teleported but is not monotonic reaching maximum for d = 4.

arXiv:1305.3443Journal of Physics A Mathematical and TheoreticalOct 8, 20135 citations

Teleporting with light : quantum optical implementations of quantum teleportation

P. T. Cochrane

This thesis is concerned with variations on, and improvements to, optical strategies of implementing quantum teleportation. In particular, I investigate four continuous variable teleportation schemes. Two schemes are based upon number-phase entanglement between two coupled harmonic oscillator modes. Joint measurements of number and phase on the coupled states are the basis for the protocols. The effects of phase decoherence on output quality are analysed and an equivalent classical protocol is introduced. The two remaining schemes improve and extend standard continuous variable teleportation. In one, coincidence measurements on the two-mode squeezed vacuum condition the entanglement resource, improving the efficacy of the protocol. In the other, the measurements made by the sender and displacements performed by the receiver are tailored to make more efficient use of the available information. In each case the protocol is described and relevant output parameters derived. The trends in output quality with respect to input parameters are interpreted and discussed.

Jan 1, 20020 citations