Evaluating quantum teleportation of coherent states

Optimal fidelity of teleportation of coherent states and entanglement

We study the Braunstein-Kimble protocol for the continuous variable teleportation of a coherent state. We determine lower and upper bounds for the optimal fidelity of teleportation, maximized over all local Gaussian operations for a given entanglement of the two-mode Gaussian state shared by the sender (Alice) and the receiver (Bob). We also determine the optimal local transformations at Alice and Bob sites and the corresponding maximum fidelity when one restricts to local trace-preserving Gaussian completely positive maps.

Quantum teleportation between a single-rail single-photon qubit and a coherent state qubit using hybrid entanglement under decoherence effects

We study quantum teleportation between two different types of optical qubits using hybrid entanglement as a quantum channel under decoherence effects. One type of qubit employs the vacuum and single photon states for the basis, called a single-rail single-photon qubit, and the other utilizes coherent states of opposite phases. We find that teleportation from a single-rail single-photon qubit to a coherent state qubit is better than the opposite direction in terms of fidelity and success probability. We compare our results with those using a different type of hybrid entanglement between a polar…

Continuous-variable quantum teleportation of entanglement

Entangled coherent states can be used to determine the entanglement fidelity for a device that is designed to teleport coherent states. This entanglement fidelity is universal, in that the calculation is independent of the use of entangled coherent states and applies generally to the teleportation of entanglement using coherent states. The average fidelity is shown to be a poor indicator of the capability of teleporting entanglement; i.e., very high average fidelity for the quantum teleportation apparatus can still result in low entanglement fidelity for one mode of the two-mode entangled cohe…

利用多体偶和奇j自旋相干态作为资源提高任意叠加相干态的量子隐形传态概率效率

Improving the probabilistic quantum teleportation efficiency of arbitrary superposed coherent state using multipartite even and odd j-spin coherent states as resource

提出利用多体偶奇j自旋相干态作为纠缠资源，通过重复GHZ态测量实现任意叠加相干态的高效概率量子隐形传态，显著提升平均保真度与成功概率。

利用量子隐形传态驯服相干噪声

Taming coherent noise with teleportation

本文证明量子隐形传态可将相干错误整形为泡利错误，使CSS码在相干噪声下的性能可经典模拟且阈值可解析证明，有望替代随机编译。

Quantum teleportation with pair-coherent states

Recently it has been argued that all presently performed continuous variable quantum teleportation experiments could be explained using a local hidden variable theory. In this paper we study a modification of the original protocol which requires a fully quantum mechanical explanation even when coherent states are teleported. Our calculations of the fidelity of teleportation using a pair-coherent state under ideal conditions suggests that fidelity above the required limit of 1/2 may be achievable in an experiment also.

Near-Complete Teleportation of a Superposed Coherent State

The four Bell-type entangled coherent states, |α>|-α> \pm |-α> |α> and |α>|α> \pm |-α> |-α>, can be discriminated with a high probability using only linear optical means, as long as |α| is not too small. Based on this observation, we propose a simple scheme to almost completely teleport a superposed coherent state. The nonunitary transformation, that is required to complete the teleportation, can be achieved by embedding the receiver's field state in a larger Hilbert space consisting of the field and a single atom and performing a unitary transformation on this Hilbert space.

Bell-state measurement and quantum teleportation using linear optics: two-photon pairs, entangled coherent states, and hybrid entanglement

We review and compare Bell-state measurement and quantum teleportation schemes using linear optics with three different types of resources, i.e., two-photon pairs, entangled coherent states and hybrid entangled states. Remarkably, perfect teleportation with linear optics is possible in principle based on a hybrid approach that combines two-photon pairs and entangled coherent states. It turns out that hybrid approach allows to perform Bell-state measurement and local Pauli operations in a deterministic way, while it requires photon number resolving measurements.

Full Bloch sphere teleportation of spinor Bose-Einstein condensates and spin ensembles

Quantum teleportation is the transfer of quantum information between two locations by the use of shared entanglement. Current teleportation schemes broadly fall under one of two categories, of either qubit or continuous variables teleportation. Spin coherent states on spin ensembles can be teleported under the continuous variables approximation for states with small deviations from a given polarization. However, for spin coherent states with large deviations, no convenient teleportation protocol exists. Recently, we introduced a teleportation scheme where a spin coherent state lying on the equ…

Entangled coherent states: teleportation and decoherence

When a superposition $(|α>-|-α>)$ of two coherent states with opposite phase falls upon a 50-50 beamsplitter, the resulting state is entangled. Remarkably, the amount of entanglement is exactly 1 ebit, irrespective of $α$, as was recently discovered by O. Hirota and M. Sasaki. Here we discuss decoherence properties of such states and give a simple protocol that teleports one qubit encoded in Schrödinger cat states

Quantum teleportation of spin coherent states: beyond continuous variables teleportation

We introduce a quantum teleportation scheme that can transfer a macroscopic spin coherent state between two locations. In the scheme a large number of copies of a qubit, such as realized in a coherent two-component Bose-Einstein condensate, is teleported onto a distant macroscopic spin coherent state using only elementary operations and measurements. We analyze the error of the protocol with the number of particles N in the spin coherent state under decoherence and find that it scales favorably with N.

基于贝尔态测量的量子态传输与相干误差

Quantum teleportation with partially entangled joint measurements induced by coherent errors

研究探讨了贝尔态测量中相干误差对量子态传输性能的影响，提出通过恢复部分纠缠测量来实现单位保真度传输的策略，并推导了测量纠缠与信道纠缠之间的定量关系。

集成生成和净化纠缠相干态用于非高斯 teleportation

Integrated Generation and Purification of Entangled Coherent States for Non-Gaussian Teleportation

本文提出了一种集成光子方案，通过光子子traction和催化生成高保真度的非高斯纠缠相干态，实现了高保真度的量子 teleportation，超越了经典极限。

Quantum Teleportation and Beam Splitting

Following the previous paper in which quantum teleportation is rig orously discussed with coherent entangled states given by beam splittings, we further discuss two types of models, perfect teleportation model and non-perfect teleportation model, in general scheme. Then the difference among several models, i.e., the perfect models and the non-perfect models, is studied. Our teleportation models are constructed by means of coherent states in some Fock space with counting measures, so that our model can be treated in the frame of usual optical communication.

Quantum teleportation and entanglement swapping of matter qubits with coherent multiphoton states

Protocols for probabilistic entanglement-assisted quantum teleportation and for entanglement swapping of material qubits are presented. They are based on a protocol for postselective Bell-state projection which is capable of projecting two material qubits onto a Bell state with the help of ancillary coherent multiphoton states and postselection by balanced homodyne photodetection. Provided this photonic postselection is successful we explore the theoretical possibilities of realizing unit fidelity quantum teleportation and entanglement swapping with $25\%$ success probability. This photon-assi…

Computation with Coherent States via Teleportations to and from a Quantum Bus

In this paper we present results illustrating the power and flexibility of one-bit teleportations in quantum bus computation. We first show a scheme to perform a universal set of gates on continuous variable modes, which we call a quantum bus or qubus, using controlled phase-space rotations, homodyne detection, ancilla qubits and single qubit measurement. The resource usage for this scheme is lower than any previous scheme to date. We then illustrate how one-bit teleportations into a qubus can be used to encode qubit states into a quantum repetition code, which in turn can be used as an effici…

Teleportation using squeezed single photons

We present an analysis of squeezed single photon states as a resource for teleportation of coherent state qubits and propose proof-of-principle experiments for the demonstration of coherent state teleportation and entanglement swapping. We include an analysis of the squeezed vacuum as a simpler approximation to small-amplitude cat states. We also investigate the effects of imperfect sources and inefficient detection on the proposed experiments.

Increasing Average Fidelity by Using Non-Maximally Entangled Resource in Teleportation of Superposed Coherent States

We consider the problem of teleporting superposed coherent state using non-maximally entangled coherent state as quantum channel and study the effect of entanglement over quality of teleportation. We show that if maximally entangled coherent state (MECS) used by Van Enk and Hirota [Phys. Rev. A 64, 022313 (2001)] and by H Prakash et al. [Phys. Rev. A 75, 044305 (2007)] is replaced by a particular non-maximally entangled coherent state (NMECS), average fidelity of quantum teleportation increases appreciably at small coherent amplitudes. Since it is very challenging to produce superposed coheren…

基于量子隐形传态的光相干态无噪声放大

Teleportation-based noiseless quantum amplification of coherent states of light

本文提出一种基于量子隐形传态的无噪声光放大方案，将概率放大操作编码到双模纠缠态中，仅需光子相减与压缩真空态，并建立相空间模型分析实验不完美因素的影响。

通过多部分Glauber相干态实现偶相干态与奇相干态的双向量子隐形传态：理论与实现

Bidirectional quantum teleportation of even and odd coherent states through the multipartite Glauber coherent state: Theory and implementation

提出基于多部分Glauber相干态的双向量子隐形传态协议，利用QFI和HSS优化触发相位估计，实现Alice与Bob间偶、奇相干态的高效双向传输与重构。

近完美的连续与离散编码间量子 teleportation

Near-perfect quantum teleportation between continuous and discrete encodings

该研究通过结合交叉Kerr非线性与被动线性光学元件，实现了从离散变量到连续变量的近完美量子 teleportation。

Secure continuous variable quantum teleportation and Einstein-Podolsky-Rosen steering

We investigate the resources needed for secure teleportation of coherent states. We extend continuous variable teleportation to include quantum tele-amplification protocols, that allow non-unity classical gains and a pre-amplification or post-attenuation of the coherent state. We show that, for arbitrary Gaussian protocols and a significant class of Gaussian resources, two-way steering is required to achieve a teleportation fidelity beyond the no-cloning threshold. This provides an operational connection between Gaussian steerability and secure teleportation. We present practical recipes sugge…

Controlled Quantum Teleportation of Superposed Coherent State using GHZ Entangled Coherent State

Controlled quantum teleportation of superposed coherent states using GHZ entangled 3-mode coherent states is studied. Proposed scheme can be implemented experimentally using linear optical components such as a symmetric lossless beam splitter, two phase-shifters and two photon counters. Fidelity is found close to unity for appreciable mean number of photons in coherent states and is 0.99 for mean photon number equal to two.

Quantum teleportation criteria for continuous variables

We discuss the criteria presently used for evaluating the efficiency of quantum teleportation schemes for continuous variables. It is argued that the fidelity criterion used so far has some severe drawbacks, and that a fidelity value larger than 2/3 is actually required for successful quantum teleportation. This value has never been reached experimentally so far.

Two different types of optical hybrid qubits for teleportation in a lossy environment

We investigate the performance of quantum teleportation under a lossy environment using two different types of optical hybrid qubits. One is the hybrid of the vacuum and single-photon states with coherent states and the other is the hybrid of polarized single-photon states with coherent states. We have shown that the hybrid qubit using vacuum and single-photon states is generally more robust to photon loss effects compared to the one using the photon polarization with respect to fidelities and success probabilities of quantum teleportation.

Hybrid teleportation via entangled coherent states in circuit quantum electrodynamics

We propose a deterministic scheme for teleporting an unknown qubit through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states brings a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. This scheme further enables applications for quantum information processing in the same architecture of circuit-QED suc…

利用 Bell 相干态实现任意薛定谔猫相干态的单向循环量子隐形传态

Unidirectional Cyclic Quantum Teleportation of Arbitrary Schrodinger Cat Coherent-states via Bell Coherent-States

该研究以三个 Bell 相干态簇为信道，结合线性光学器件与光子数分辨探测，实现三方间任意薛定谔猫相干态的单向循环量子隐形传态，并分析保真及近保真情形的成功概率。

Quantum teleportation of hybrid qubits and single-photon qubits using Gaussian resources

In this paper, we compare single-photon qubits and hybrid qubits as information carriers through quantum teleportation using a Gaussian continuous-variable channel. A hybrid qubit in our study is in the form of entanglement between a coherent state and a single photon. We find that hybrid qubits outperform photonic qubits when coherent amplitudes of the hybrid qubits are as low as $α\lesssim 1$, while photonic qubits yield better results for larger amplitudes. We analyze effects of photon losses, and observe that the overall character of teleportation for different qubits remains the same alth…

Super sensitivity and super resolution with quantum teleportation

We propose a method for quantum enhanced phase estimation based on continuous variable (CV) quantum teleportation. The phase shift probed by a coherent state can be enhanced by repeatedly teleporting the state back to interact with the phase shift again using a supply of two-mode squeezed vacuum states. In this way, both super resolution and super sensitivity can be obtained due to the coherent addition of the phase shift. The protocol enables Heisenberg limited sensitivity and super- resolution given sufficiently strong squeezing. The proposed method could be implemented with current or near-…

Discrete teleportation protocol of continuum spectra field states

A discrete protocol for teleportation of superpositions of coherent states of optical cavity fields is presented. Displacement and parity operators are unconventionally used in Bell-like measurement for field states.

以相干态为例的光的完整态隐形传态方案

Teleportation scheme for the complete state of light at the example of coherent states

提出一种通过逐像素隐形传态实现光空间与光子数自由度完整传态的方案，以相干态为例，并验证了理想及现实纠缠资源下的可行性。

Teleportation of Cavity Field States via Cavity QED

In this article we discuss two schemes of teleportation of cavity field states. In the first scheme we consider cavities prepared in a coherent state and in the second scheme we consider cavities prepared in a superposition of zero and one Fock states.

非对称双向量子隐形传态：任意双模信息态

Asymmetric Bidirectional Quantum Teleportation: Arbitrary bi-modal Information State

本文提出一种利用簇态和线性光学器件实现非对称双向量子隐形传态的策略，可在发送方与接收方间同时传送任意双模纠缠相干态与薛定谔猫相干态，并证明强相干光场下保真度趋近于1。

Odd numbers of photons and teleportation

Several teleportation protocols, namely those using entangled coherent states, entangled squeezed states, and the single-photon EPR state, are all shown to be particular instances of a more general scheme that relies on the detection of an odd number of photons.

双色量子态弱相干极化态的城域光纤量子 teleportation

Bichromatic Quantum Teleportation of Weak Coherent Polarization States on a Metropolitan Fiber

利用城域光纤实现弱相干极化态的量子 teleportation，展示其在真实环境下的高保真度传输及与现有电信基础设施的兼容性。

No-cloning theorem and teleportation criteria for quantum continuous variables

We discuss the criteria presently used for evaluating the efficiency of quantum teleportation schemes for continuous variables. Using an argument based upon the difference between 1-to-2 quantum cloning (quantum duplication) and 1-to-infinity cloning (classical measurement), we show that a fidelity value larger than 2/3 is required for successful quantum teleportation of coherent states. This value has not been reached experimentally so far.

Optimal fidelity of teleportation with continuous-variable using three-tunable parameters in realistic environment

We introduce three tunable parameters to optimize the fidelity of quantum teleportation with continuous-variable in nonideal scheme. Using the characteristic function formalism, we present the condition that the teleportation fidelity is independent of the amplitude of input coherent states for any entangled resource. Then we investigate the effects of tunable parameters on the fidelity with or without the presence of environment and imperfect measurements, by analytically deriving the expression of fidelity for three different input coherent state distributions. It is shown that, for the line…

Coherent Communication with Continuous Quantum Variables

The coherent bit (cobit) channel is a resource intermediate between classical and quantum communication. It produces coherent versions of teleportation and superdense coding. We extend the cobit channel to continuous variables by providing a definition of the coherent nat (conat) channel. We construct several coherent protocols that use both a position-quadrature and a momentum-quadrature conat channel with finite squeezing. Finally, we show that the quality of squeezing diminishes through successive compositions of coherent teleportation and superdense coding.

Coherent-state optical qudit cluster state generation and teleportation via homodyne detection

Defining a computational basis of pseudo-number states, we interpret a coherent state of large amplitude, $|α|\gg\frac{d}{2π}$, as a qudit --- a $d$-level quantum system --- in a state that is an even superposition of $d$ pseudo-number states. A pair of such coherent-state qudits can be prepared in maximally entangled state by generalized Controlled-$Z$ operation that is based on cross-Kerr nonlinearity, which can be weak for large $d$. Hence, a coherent-state optical qudit cluster state can be prepared by repetitive application of the generalized Controlled-$Z$ operation to a set of coherent …

连续变量光量子模与离散变量固态量子比特之间的量子隐形传态

Quantum teleportation between a continuous-variable optical qumode and a discrete-variable solid-state qubit

本文提出一种利用混合纠缠将连续变量光量子比特隐形传态至离散变量固态量子比特的方案，通过仅依赖光零差检测和自旋极化测量的新贝尔态测量方法，在现实噪声下仍可实现超越经典极限的保真度。

Gain tuning and fidelity in continuous variable quantum teleportation

The fidelity of continuous variable teleportation can be optimized by changing the gain in the modulation of the output field. We discuss the gain dependence of fidelity for coherent, vacuum and one photon inputs and propose optimal gain tuning strategies for corresponding input selections.

A scheme for total quantum teleportation

We address the issue of totally teleporting the quantum state of an external particle, as opposed to studies on partial teleportation of external single-particle states, total teleportation of coherent states and encoded single-particle states, and intramolecular teleportation of nuclear spin states. We find a set of commuting observables whose measurement directly projects onto the Bell-basis and discuss a possible experiment, based on two-photon absorption, allowing, for the first time, total teleportation of the state of a single external photon through a direct projective measurement.

非均匀先验分布下的量子隐形传态基准

Benchmark for Quantum Teleportation with Non-Uniform Prior Distributions

针对非均匀先验分布（von Mises-Fisher分布）的量子态，利用贝叶斯方法推导了单量子比特和多量子比特系统（自旋相干态）的隐形传态保真度基准，发现量子优势的保真度阈值可显著高于均匀分布情况。

Quantum teleportation of qudits by means of generalized quasi-Bell states of light

Quantum superpositions of coherent states are produced both in microwave and optical domains, and are considered realizations of the famous "Schrödinger cat" state. The recent progress shows an increase in the number of components and the number of modes involved. Our work creates a theoretical framework for treatment of multicomponent two-mode Schrödinger cat states. We consider a class of single-mode states, which are superpositions of $N$ coherent states lying on a circle in the phase space. In this class we consider an orthonormal basis created by rotationally-invariant circular states (RI…

High Fidelity Teleportation of Continuous Variable Quantum States using Delocalized Single Photons

Traditional continuous variable teleportation can only approach unit fidelity in the limit of an infinite (and unphysical) amount of squeezing. We describe a new method for continuous variable teleportation that approaches unit fidelity with finite resources. The protocol is not based on squeezed states as in traditional teleportation but on an ensemble of single photon entangled states. We characterize the teleportation scheme with coherent states, Schrodinger cat states and two-mode squeezed state and we find several situations in which near-unity teleportation fidelity can be obtained with …

利用光子减除和光子增补双模压缩相干态的连续变量量子隐形传态

Continuous variable quantum teleportation using photon subtracted and photon added two mode squeezed coherent state

本文研究光子减除和增补的双模压缩相干态作为连续变量量子隐形传态资源，推导Wigner特征函数并计算保真度，发现对称光子减除在广泛压缩范围提升性能，而增补操作作用有限。

Entangled coherent states versus entangled photon pairs for practical quantum information processing

We compare effects of decoherence and detection inefficiency on entangled coherent states (ECSs) and entangled photon pairs (EPPs), both of which are known to be particularly useful for quantum information processing (QIP). When decoherence effects caused by photon losses are heavy, the ECSs outperform the EPPs as quantum channels for teleportation both in fidelities and in success probabilities. On the other hand, when inefficient detectors are used, the teleportation scheme using the ECSs suffers undetected errors that result in the degradation of fidelity, while this is not the case for the…

Quantum teleportation using highly coherent emission from telecom C-band quantum dots

A practical way to link separate nodes in quantum networks is to send photons over the standard telecom fibre network. This requires sub-Poissonian photon sources in the telecom wavelength band around 1550 nm, where the photon coherence time has to be sufficient to enable the many interference-based technologies at the heart of quantum networks. Here, we show that droplet epitaxy InAs/InP quantum dots emitting in the telecom C-band can provide photons with coherence times exceeding 1 ns even under non-resonant excitation, more than a factor two longer than values reported for shorter wavelengt…

Minimal disturbance measurement for coherent states is non-Gaussian

In standard coherent state teleportation with shared two-mode squeezed vacuum (TMSV) state there is a trade-off between the teleportation fidelity and the fidelity of estimation of the teleported state from results of the Bell measurement. Within the class of Gaussian operations this trade-off is optimal, i.e. there is not a Gaussian operation which would give for a given output fidelity a larger estimation fidelity. We show that this trade-off can be improved by up to 2.77% if we use a suitable non-Gaussian operation. This operation can be implemented by the standard teleportation protocol in…

利用奇异纠缠相干态实现量子比特隐形传态

Teleportation of a qubit using exotic entangled coherent states

该研究从奇异 Landau 问题构造非对易空间中的准 Bell 纠缠相干态，并分析其作为非最大纠缠量子信道对量子比特隐形传态的影响。

Information extraction and quantum state distortions in continuous variable quantum teleportation

We analyze the loss of fidelity in continuous variable teleportation due to non-maximal entanglement. It is shown that the quantum state distortions correspond to the measurement back-action of a field amplitude measurement. Results for coherent states and for photon number states are presented.

Teleportation of Atomic States via Cavity Quantum Electrodynamics

In this article we discuss a scheme of teleportation of atomic states. The experimental realization proposed makes use of cavity Quatum Electrodynamics involving the interaction of Rydberg atoms with a micromaser cavity prepared in a coherent state. We start presenting a scheme to prepare atomic Bell states via the interaction of atoms with a cavity. In our scheme the cavity and some atoms play the role of auxiliary systems used to achieve the teleportation.

连续变量量子隐形传态中双模相干叠加信道的性能

Performance of a two-mode coherent superposed channel in continuous-variable quantum teleportation

引入双模叠加算符构造双模相干叠加态，通过Wigner分布和Wigner对数负性研究其非经典性和非高斯性，并作为纠缠资源用于Braunstein-Kimble连续变量隐形传态，分析非经典性和非高斯性对保真度的影响，发现特定参数下保真度超过经典阈值。

Quantum teleportation of unknown qubit beyond Bell states formalism

We suggest implementation of quantum teleportation protocol of unknown qubit beyond Bell states formalism. Hybrid entangled state composed of coherent components that belong to Alice and dual-rail single photon at Bob disposal is used. Nonlinear effect on the teleported state is realized due to peculiarity of interaction of coherent components with discrete variable state on a beam splitter. Bob performs unitary transformation after receiving the appropriate classical information. The protocol is nearly deterministic but the output state is subject to amplitude distortion which reduces the fid…