Solid-state ensemble of highly entangled photon sources at rubidium transitions

Date

Mar 3, 2017

Time

10:00 AM - 11:00 AM

Speaker

Robert Keil

Affiliation

IFW Dresden, Institut für Integrative Nanowissenschaften

Language

en

Main Topic

Materialien

Other Topics

Materialien

Host

Kristina Krummer-Meier

Description

Future quantum communication networks involve the transmission of information between separate nodes using single photons [1]. These flying qubits suffer from losses due to absorption and decoherence in optical fibers, demanding the development of new concepts of transmitting quantum states efficiently o. In 1993, Bennett et al. [2] proposed a scheme utilizing entangled photon pairs to teleport quantum information from one place to another - without the photon being actually transported. This idea can be expanded to a quantum repeater, rendering long range communication possible. Entanglement swapping, a core mechanism of the repeater, was first demonstrated by J.W. Pan et al. [3], utilizing polarization entangled photon pairs created by spontaneous parametric down-conversion. This process is characterized by Poissonian statistics, i.e. a tradeoff has to be made between source brightness and multi-photon emission probability, limiting its practicality for scalable networks significantly. Since then, many efforts have been taken to realize a deterministic, solid-state embedded source of entangled photon pairs. The emission of the cascaded decay of the bi-exciton state in single semiconductor quantum dots has been demonstrated to generate polarization entangled photon pairs provided a highly symmetric confinement potential [4]. Despite various investigated structures and material systems [5,6,7,8], many challenges remain unsolved, such as low yield, insufficient degree of entanglement and limited wavelength control. In this talk I will present a new generation of GaAs/AlGaAs QDs grown by droplet etching and nano-hole infilling, obtaining a large ensemble (almost 100%) of polarization-entangled photon emitters with record high degree of entanglement (fidelity up to F = 0.91) and unprecedented wavelength control. Therefore this material system is an attractive candidate for the realization of a solid-state quantum emitter. In the second part of my talk additional procedures for an optimized growth and a Schottky-diode sample design are presented towards further improvement of the optical properties of these promising quantum emitters.

Links

• Seminars at the IFW

Last modified: Mar 3, 2017, 9:00:16 AM