Experimental quantum teleportation

Abstract

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.The dream of teleportation is to be able to travel by simply reappearing at some distant location. An object to be teleported can be fully characterized by its properties, which in classical physics can be determined by measurement. To make a copy of that object at a distant location one does not need the original parts and piecesall that is needed is to send the scanned information so that it can be used for reconstructing the object. But how precisely can this be a true copy of the original? What if these parts and pieces are electrons, atoms and molecules? What happens to their individual quantum properties, which according to the Heisenberg's uncertainty principle cannot be measured with arbitrary precision?Bennett et al. 1 have suggested that it is possible to transfer the quantum state of a particle onto another particle-the process of quantum teleportation-provided one does not get any information about the state in the course of this transformation. This requirement can be fulfilled by using entanglement, the essential feature of quantum mechanics 2 . It describes correlations between quantum systems much stronger than any classical correlation could be.The possibility of transferring quantum information is one of the cornerstones of the emerging field of quantum communication and quantum computation 3 . Although there is fast progress in the theoretical description of quantum information processing, the difficulties in handling quantum systems have not allowed an equal advance in the experimental realization of the new proposals. Besides the promising developments of quantum cryptography 4 (the first provably secure way to send secret messages), we have only recently succeeded in demonstrating the possibility of quantum dense coding 5 , a way to quantum mechanically enhance data compression. The main reason for this slow experimental progress is that, although there exist methods to produce pairs of entangled photons 6 , entanglement has been demonstrated for atoms only very recently 7 and it has not been possible thus far to produce entangled states of more than two quanta.Here we report the first experimental verification of quantum teleportation. By producing pairs of entangled photons by the process of parametric down-conversion and using two-photon interferometry for analysing entanglement, we could transfer a quantum property (in our case the polarization state) from one photon to another. The methods developed for this experiment will be of...

Quantum Information Theory and the Foundations of Quantum Mechanics

“…On the experimental side, the focus on the ability to manipulate and control individual quantum systems, both for computational and cryptographic purposes, has led not only to detailed realisation of many of the gedanken-experiments familiar from foundational discussions (see e.g. Zeilinger (1999a)), but also to wholly new demonstrations of the oddity of the quantum world (Boschi et al, 1998;Bouwmeester et al, 1997;Furusawa et al, 1998).…”

Spin–orbit laser mode transfer via a classical analogue of quantum teleportation

“…It enables one party (Alice), to transfer an arbitrary, unknown quantum state to a second party (Bob) via the use of previously shared quantum entanglement and classical communication [34][35][36][37][38]. An investigation of an optical analogue of the teleportation protocol has been recently reported in [39], in which states of orbital angular momentum were transferred to polarization.…”

Luminescence-induced noise in single photon sources based on BBO crystals

“…For its experimental feasibility SPDC is currently the most frequent and popular technique, at least in proof-of-principle experiments [16][17][18][19][20][21]. This method makes use of a non-linear optical medium to probabilistically transform a fraction of a strong pump beam into pairs of correlated output photons denoted as signal and idler.…”