Quantum teleportation of an entangled state

Nature, 2004

Annals of Physics

The entanglement behavior of two classes of multi-qubit system, GHZ and GHZ like states passing through a generalized amplitude damping channel is discussed. Despite this channel causes degradation of the entangled properties and consequently their abilities to perform quantum teleportation, one can always improve the lower values of the entanglement and the fidelity of the teleportrd state by controlling on Bell measurements, analyzer angle and channel's strength. Using GHZ-like state within a generalized amplitude damping channel is much better than using the normal GHZstate, where the decay rate of entanglement and the fidelity of the teleported states are smaller than those depicted for GHZ state.

Alhun Aydın, 2010

Teleportation is usually seen as a science-fiction term. In spite of that, the possibility of teleportation within the range of physics laws, has been being studied since its discovery in 1993. We examine the teleportation that is done with using quantum entanglement, and we explore quantum teleportation both theoretically and experimentally, with also giving fundamental background knowledge of the process. Furthermore we discuss the philosophy of some weird quantum phenomena with regard to quantum teleportation.

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.

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

Physical Review A, 2002

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 coherent state.

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

A simplified version of quantum teleportation protocol is presented here. Its experimental confirmation will have deep implications for a better understanding of quantum entanglement with a particular projection on quantum communications.

In sections (1), (2) a channel theoretical formulation of the teleportation problem for quantum states, is given and a general solution, valid in arbitrary finite dimensions is proposed. The problem of uniqueness of the hidden key is discussed and a classification is obtained. The results in these sections survey recent joint work with Masanori Ohya.

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.

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 .

Quantum teleportation is a secure way to transfer an unknown message using a known channel implementing a simple and efficient protocol. Here, we achieve three-qubit and four-qubit quantum teleportation using a highly entangled Brown et al. state. We simulate the same using IBM quantum experience platform. Furthermore, we extend this concept to generalize N-qubit teleportation which comprises of two cases, N being odd and even. The results are verified after designing the quantum circuits and simulating on the quantum simulator.

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,

New Journal of Physics, 2002

We first consider teleportation of entangled states shared between Claire and Alice to Bob1 and Bob2 when Alice and the two Bobs share a single copy of a GHZ state and where all the four parties are at distant locations. We extend this result to a more general state than GHZ-state and show that still a class of pure entangled states can be teleported, where the entanglement of this class ranges from 0 to e (≤1), depending on the entanglement (defined in the text) of the channel state. We then generalize this situation to the case of teleportation of entangled states shared between Claire1, Claire2, . . . , Claire(N − 1) and Alice to Bob1, Bob2, . . . , BobN when Alice and the N Bobs share a single copy of a GHZ-class state and where again all the 2N parties are at distant locations. Quantum teleportation, proposed by Bennett Brassard, Crepeau, Jozsa, Peres and Wootters (BBCJPW) [1], is a protocol by which the information of an arbitrary state of a quantum mechanical system can be transferred (teleported) exactly from one location (where say, Alice is operating) to a possibly distant location (operated say, by Bob) by using only local operations and classical communication, without sending the system itself (thus, at Bob's location, the exact † Present address: Note that in this way, Alice could make Bob and Claire share an arbitrary entangled state of two qubits, whether pure or mixed. But henceforth we shall consider entanglement teleportation of pure states only.

Physical Review A