Building Blocks for a Solid-State Quantum Repeater

Date

Nov 28, 2017

Time

1:30 PM - 2:30 PM

Speaker

Michael Zopf

Affiliation

IIN

Language

en

Main Topic

Materialien

Other Topics

Materialien, Physik

Host

Kristina Krummer-Meier

Description

Future quantum networks involve the transmission of information between different nodes using single photons and entangled photon pairs. To overcome transmission losses over large distances a so called quantum repeater is essential, which is the quantum mechanical equivalent to a classical signal amplifier. One key component of this technology is the entanglement swapping scheme [1]. It relies on quantum interference between two entangled photon pairs, and photon storage in quantum memories. Semiconductor quantum dots (QDs) are leading candidates for the deterministic emission of single photons and entangled photon pairs. However, matching the properties of two individual sources remains a challenge. Due to the random growth nature of QDs, post-growth tuning techniques like e.g. strain tuning [2] become inevitable. GaAs/AlGaAs QDs are prominent candidates for storing photons in rubidium based quantum memories [3], since they can be tailored to emit close to the Rb D1 or D2 transitions. In this talk, achievements in providing building blocks for a solid-state quantum repeater are presented. On-demand emission of highly entangled photon pairs in GaAs/AlGaAs QDs has been realized, with possible entanglement fidelities of > 0.9 [4]. Two-photon interference between two remote GaAs/AlGaAs QDs has been observed. In order to obtain stable long-term interference, and to demonstrate the potential for storage in Rb based quantum memories, we applied active frequency feedback to the QDs. As frequency discriminator we used a Rb based Faraday anomalous Dispersion optical filter. The properties of this filter can be tuned in order to bring the frequency-locked QD emission into resonance with the Rb hyperfine levels for future photon storage experiments. Improved long-term interference is shown using frequency-locked QDs. In conclusion, the currently ongoing experiment of entanglement swapping using one QD source will be presented. [1] R. Jin et al., Sci. Rep. 5, 9333 (2015) [2] Y. Chen et al., Nature Comm. 7, 10387 (2016) [3] J. Wolters et al., Phys. Rev. Lett. 119, 060502 (2017) [4] R. Keil and M. Zopf et al., Nature Comm. 8, 15501 (2017)

Links

• Seminars at the IFW

Last modified: Nov 28, 2017, 8:50:56 AM