Quantum teleportation and entanglement swapping with linear optics logic gates

Christian Schmid,Anton Zeilinger,Nikolai Kiesel,Rupert Ursin,Harald Weinfurter,Ulrich K Weber

doi:10.1088/0031-8949/11/3/033008

Abstract

We report on the usage of a linear optics phase gate for distinguishing all four Bell states simultaneously in a quantum teleportation and entanglement swapping protocol. This is demonstrated by full-state tomography of the one- and two-qubit output states of the two protocols, yielding average state fidelities of about 0.83 and 0.77, respectively. In addition, the performance of the teleportation channel is characterized by the quantum process tomography. The non-classical properties of the entanglement swapping output states are further confirmed by the violation of a CHSH-type Bell inequality of 2.14 on average.

Highlights

Quantum teleportation [1] and entanglement swapping [2] are fundamental elements of quantum communication protocols and play an important role in a number of applications
A significant improvement with respect to reliability and stability of a linear optics logic gate was reported [21]–[25] which allows such gates to be employed in multi-photon quantum communication protocols
We report on the implementation of quantum teleportation and entanglement swapping including probabilistic, complete Bell state analysis (BSA) accomplished by the use of a linear optics cphase gate

Summary

Introduction

Quantum teleportation [1] and entanglement swapping [2] are fundamental elements of quantum communication protocols and play an important role in a number of applications Both processes rely on the projection of two qubits onto maximally entangled Bell states. As introduced by Knill, Laflamme and Milburn (KLM) [14], all optical two-qubit quantum logic can be achieved nearly deterministically using linear optics plus conditioned detection and ancillary qubits. The latter can be omitted when probabilistic gate operation is sufficient [15, 16]. We report on the implementation of quantum teleportation and entanglement swapping including probabilistic, complete Bell state analysis (BSA) accomplished by the use of a linear optics cphase gate

The Bell-state measurement

Photon state preparation and detection

Teleportation

Entanglement swapping

Discussion and conclusion