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2000, Physical Review Letters
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.
Canadian Journal of Physics, 2017
We develop a theory to teleport an unknown quantum state using entanglement between two distant parties. Our theory takes into account experimental limitations due to contribution of multi-photon pair production of parametric down conversion source, inefficiency and dark counts of detectors and channel losses. We use a linear optics setup for quantum teleportation of an unknown quantum state by performing Bell state measurement by the sender. Our theory successfully provides a model for experimentalists to optimize the fidelity by adjusting the experimental parameters. We apply our model to a recent experiment on quantum teleportation and the results obtained by our model are in good agreement with the experiment results.
2003
Recent experiments confirm that quantum teleportation is possible at least for states of photons and nuclear spins. The quantum teleportation is not only a curious effect but a fundamental protocol of quantum communication and quantum computing. The principles of the quantum teleportation and the entanglement swapping are explained, and physical realizations of teleportation of optical and atomic states are discussed.
Quantum teleportation 1 provides a "disembodied" way to transfer quantum states from one object to another at a distant location, assisted by priorly shared entangled states and a classical communication channel. In addition to its fundamental interest, teleportation has been recognized as an important element in long-distance quantum communication 2 , distributed quantum networks 3 and measurement-based quantum computation 4,5. There have been numerous demonstrations of teleportation in different physical systems such as photons 6-8 , atoms 9 , ions 10,11 , electrons 12 , and superconducting circuits 13. Yet, all the previous experiments were limited to teleportation of one degree of freedom (DoF) only. However, a single quantum particle can naturally possess various DoFs-internal and external-and with coherent coupling among them. A fundamental open challenge is to simultaneously teleport multiple DoFs, which is necessary to fully describe a quantum particle, thereby truly teleporting it intactly. Here, we demonstrate the first teleportation of the composite quantum states of a single photon encoded in both the spin and orbital angular momentum. We develop a method to project and discriminate hyper-entangled Bell states exploiting probabilistic quantum non-demolition measurement, which can be extended to more DoFs. We verify the teleportation for both spin-orbit product states and hybrid entangled state, and achieve a teleportation fidelity ranging from 0.57 to 0.68,
2011
This paper contains an overview of the concept of photon entanglement and discusses generating EPR photon pairs and performing Bell state measurements on them. The procedure of quantum teleportation, or transferring the quantum state of a particle onto another particle, is described in detail. The experimental progress in performing such operations is reviewed in relationship to the developing field of quantum communication.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1998
Quantum teleportation-the transmission and reconstruction over arbitrary distances of the state of a quantum system-is demonstrated experimentally. During teleportation, an initial photon which carries the polarization that is to be transferred and one of a pair of entangled photons are subjected to a measurement such that the second photon of the entangled pair acquires the polarization of the initial photon. This latter photon can be arbitrarily far away from the initial one. Quantum teleportation will be a critical ingredient for quantum computation networks.
Nature, 2006
Quantum teleportation 1 is an important ingredient in distributed quantum networks 2 , and can also serve as an elementary operation in quantum computers 3 . Teleportation was first demonstrated as a transfer of a quantum state of light onto another light beam 4-6 ; later developments used optical relays 7 and demonstrated entanglement swapping for continuous variables 8 . The teleportation of a quantum state between two single material particles (trapped ions) has now also been achieved 9,10 . Here we demonstrate teleportation between objects of a different nature-light and matter, which respectively represent 'flying' and 'stationary' media. A quantum state encoded in a light pulse is teleported onto a macroscopic object (an atomic ensemble containing 10 12 caesium atoms). Deterministic teleportation is achieved for sets of coherent states with mean photon number (n) up to a few hundred. The fidelities are 0.58±0.02 for n=20 and 0.60±0.02 for n=5higher than any classical state transfer can possibly achieve 11 . Besides being of fundamental interest, teleportation using a macroscopic atomic ensemble is relevant for the practical implementation of a quantum repeater 2 . An important factor for the implementation of quantum networks is the teleportation distance between transmitter and receiver; this is 0.5 metres in the present experiment. As our experiment uses propagating light to achieve the entanglement of light and atoms required for teleportation, the present approach should be scalable to longer distances. Quantum teleportation-a disembodied transfer of a quantum state with the help of distributed entanglement-was proposed in a seminal paper 1 . The generic protocol of quantum teleportation begins with the creation of a pair of entangled objects which are shared by two parties, Alice and Bob. This step establishes a quantum link between them. Alice receives an object to be teleported and performs a joint measurement on this atomŝ 4 x x J J N = = , and the transverse projections with minimal quantum uncertainties, x z y J J J 2 1 2 2
Physical Review A, 2000
2003
Since its discovery in 1993, quantum teleportation (QT) is a subject for intense theoretical and experimental studies. Experimental demonstration of QT has so far been limited to teleportation of light. In this paper, we propose a new experimental scheme for QT of nuclear matter. We show that the standard technique of nuclear physics experiment could be successfully applied for teleportation of spin states of atomic nuclei. We claim that there are no theoretical prohibitions upon a possibility of a complete Bell measurement, therefore, the implementation of all the four quantum communication channels is at least theoretically possible. A general expression for scattering amplitude of two 1/2-spin particles is given in the Bell operator basis, and the peculiarities of Bell states registration are briey discussed.
Journal of the Physical Society of Japan, 2003
We present an overview of the method for generating entangled photon pairs via spontaneous parametric down conversion and the experimental method of detecting entangled states or Bellstates with the use of photon statistics, the two key systems required to realize quantum state teleportation and other related experiments. As a proof of the quantum nature of teleportation we performed an entanglement swapping experiment, where the teleported state itself was entangled. The experiment clearly showed that the entanglement survived the teleportation, as the quantum correlations of the teleported photon violated Bell's inequality.
Nature Physics, 2006
Q uantum teleportation 1 , a way to transfer the state of a quantum system from one location to another, is central to quantum communication 2 and plays an important role in a number of quantum computation protocols 3-5 . Previous experimental demonstrations have been implemented with single photonic 6-11 or ionic qubits 12,13 . However, teleportation of single qubits is insufficient for a large-scale realization of quantum communication and computation 2-5 . Here, we present the experimental realization of quantum teleportation of a twoqubit composite system. In the experiment, we develop and exploit a six-photon interferometer to teleport an arbitrary polarization state of two photons. The observed teleportation fidelities for different initial states are all well beyond the state estimation limit of 0.40 for a two-qubit system 14 . Not only does our six-photon interferometer provide an important step towards teleportation of a complex system, it will also enable future experimental investigations on a number of fundamental quantum communication and computation protocols 3,15-18 .
Physical Review A, 2005
In a recent paper ͓Phys. Rev. A 70, 025803 ͑2004͔͒ we presented a scheme to teleport an entanglement of zero-and one-photon states from a bimodal cavity to another one, with 100% success probability. Here, inspired by recent results in the literature, we have modified our previous proposal to teleport the same entangled state without using Bell-state measurements. For comparison, the time spent, the fidelity, and the success probability for this teleportation are considered.
Scientific reports, 2018
We investigate two-copy scenario of quantum teleportation based on Bell measurements. The detailed protocol is presented and the general expression of the corresponding optimal teleportation fidelity is derived, which is given by the two-copy fully entangled fraction that is invariant under local unitary transformations. We prove that under a specific case of the protocol, which is significant for improving the optimal fidelity, the set of states with their two-copy fully entangled fractions bounded by a threshold value that required for useful two-copy teleportation is convex and compact. Hence the witness operators exist to separate states that are useful for two-copy teleportation from the rest ones. Moreover, we show that the optimal fidelity of two-copy teleportation surpasses that of the original one copy teleportation.
Physical Review A, 2000
We study the experimental realisation of quantum teleportation as performed by Bouwmeester et al. [Nature 390, 575 (1997)] and the adjustments to it suggested by Braunstein and Kimble [Nature 394, 841 (1998)]. These suggestions include the employment of a detector cascade and a relative slow-down of one of the two down-converters. We show that coincidences between photonpairs from parametric down-conversion automatically probe the non-Poissonian structure of these sources. Furthermore, we find that detector cascading is of limited use, and that modifying the relative strengths of the down-conversion efficiencies will increase the time of the experiment to the order of weeks. Our analysis therefore points to the benefits of single-photon detectors in non-postselected type experiments, a technology currently requiring roughly 6 • K operating conditions. PACS number(s): 03.67.*, 42.50.Dv Quantum entanglement, an aspect of quantum theory already recognised in the early days, clearly sets quantum mechanics apart from classical mechanics. More recently, fundamentally new phenomena involving entanglement such as cryptography, error correction and dense coding have been discovered . In particular, the field has witnessed major steps forward with the experimental realisation of quantum teleportation [4-9].
Physical Review A, 2001
We investigate the changes to a single photon state caused by the non-maximal entanglement in continuous variable quantum teleportation. It is shown that the teleportation measurement introduces field coherence in the output.
Physical Review Letters, 1998
We report on a quantum optical experimental implementation of teleportation of unknown pure quantum states. This realizes all of the nonlocal aspects of the original scheme proposed by Bennett et al. and is equivalent to it up to a local operation. We exhibit results for the teleportation of a linearly polarized state and of an elliptically polarized state. We show that the experimental results cannot be explained in terms of a classical channel alone. The Bell measurement in our experiment can distinguish between all four Bell states simultaneously allowing, in the ideal case, a 100% success rate of teleportation. [S0031-9007(97)05275-7] PACS numbers: 03.65.Bz, 03.67. -a, 42.50. -p, 89.70. + c In Ref. [1], Bennett et al.
We present a short summary of progress achieved at the Center for Engineering Science Advanced Research (CESAR) of the Oak Ridge National Laboratory (ORNL) in the recently initiated Quantum Teleportation project. The primary objective of this effort is to study the signaling potential of quantum information processing systems based on quantum entanglement. Our initial effort has focused on the development and demonstration of a novel, ultra-bright EPR source, based upon the innovative concept of cascaded type-II optical parametric downconversion. The main features of this source are analyzed, and results of a multi-photon entanglement experiment are presented. Theoretical challenges for superluminal communications are also highlighted.
Physical Review A, 2001
A single-particle entangled state can be generated by illuminating a beam splitter with a single photon. Quantum teleportation utilizing such a single-particle entangled state can be successfully achieved with a simple setup consisting only of linear optical devices such as beam splitters and phase shifters. Application of the locality assumption to a single-particle entangled state leads to Bell's inequality, a violation of which signifies the nonlocal nature of a single particle.
Physical Review A, 2000
We consider the teleportation of entangled two-particle and multiparticle states and present a scheme for the teleportation that may be suitable for both entangled atomic states or field states inside high-Q cavities.
Physical Review A, 1998
We investigate the ''teleportation'' of a quantum state using three-particle entanglement to either one of two receivers in such a way that, generally, either one of the two, but only one, can fully reconstruct the quantum state conditioned on the measurement outcome of the other. We furthermore delineate the similarities between this process and a quantum nondemolition measurement. ͓S1050-2947͑98͒08812-X͔
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