Entanglement teleportation with photons from quantum dots: towards a solid-state based quantum network

Abstract

Semiconductor quantum dots are currently emerging as one of the most promising sources of non-classical light on which to base future quantum networks. They can generate single photons as well as pairs of entangled photons with unprecedented brightness, indistinguishability, and degree of entanglement. These features have very recently opened up the possibility to perform advanced quantum optics protocols that were previously inaccessible to single quantum emitters. In this work, we report on two experiments that use the non-local properties of entanglement to teleport quantum states: three-photon state teleportation and four-photon entanglement teleportation. We discuss all the experimental results in light of a theoretical model that we develop to account for the nonidealities of the quantum source. The excellent agreement between theory and experiment enables a deep understanding of how each parameter of the source affects the teleportation fidelities and it pinpoints the requirements needed to overcome the classical limits. Finally, our model suggests how to further improve quantum-dot entangled-photon sources for practical quantum networks.

Quantum key distribution with entangled photons generated on demand by a quantum dot

“…Figure 2B reports an autocorrelation measurement run on the exciton emission line with a dedicated Hanbury-Brown and Twiss setup in laboratory conditions, corresponding to , a value mainly limited by the detector time resolution. Even if this figure were to be entirely attributed to multiphoton emission, it would still be a minor cause of below-unity entanglement fidelity, with an expected contribution of 0.3% in a simple model of the density matrix ( 30 ). With a similar experimental procedure, we measure the cross-correlation function between the two photons of the entangled pair to determine the fidelity of preparation, defined as the probability of a laser pulse to promote the QD from the optically active ground state to the biexciton state, followed by the two-photon emission.…”

Quantum Plasmonics: Energy Transport Through Plasmonic Gap

“…[12,33,[57][58][59] For example, coherency, entanglement, and tunneling can be further explored in quantum interferencebased devices, [60,61] single-photon emitters and detectors, [62,63] and quantum networks. [64][65][66][67] The quantum effect is explained further (in terms of the sub-nanometer size gap between two resonators) in the last section of this review. As discussed at length in the literature, plasmon coupling can occur over a 5 nm gap distance between plasmon dimers; thus, it is categorized as belonging to the classical regime.…”

Quantum teleportation with imperfect quantum dots

“…In this way, the polarization density matrix is derived from the Stokes parameters 41 . The total rate of threefold coincidences is 0.8 Hz, which is expected from the efficiency figures of merit of the setup and the source 30 . In Fig.…”

“…Figure 1a shows the emission spectrum of the QD studied in this paper, which contains the signature of the two optical transitions of the biexciton-exciton (XX-X) radiative cascade. Using a resonant two-photon excitation scheme, the photon pairs are produced with a preparation fidelity of 0.88, as estimated by intensity cross-correlation measurements 30 . To show how the protocol works with suboptimal QDs, we chose one with a linewidth far larger than the average value of the sample.…”

“…The features of the entangled photon source which are more relevant to the performance of the quantum teleportation operation are the degree of entanglement and photon indistinguishability 30 . In Fig.…”