第75回APMセミナー開催

第７５回ＡＰＭセミナ-のお知らせ
～先端フォトニクス材料ユニット～
Entangled photon-pair generation
in droplet epitaxial quantum dots
日時：６月６日（金） 15:00 ～16:00
場所：千現地区研究本館8階中セミナー室
講演者： Dr. Xiangming Liu
（ナノフォトニクスグループ）
A source of single photons and entangled photon pairs is essential for quantum
information and communications. The generation of entangled photon pairs
can be achieved by using radiative decay of biexcitons in a quantum dot (QD).
Recently, employing droplet epitaxy we have realized symmetric GaAs QDs on
GaAs(111)A substrates, which yield the generation of highly entangled photon
pairs without external tuning in visible spectrum range. However, there are still
many challenges for the realization of practical QD photon sources. One of the
important issues is to extend the emission wavelengths to the telecom band. In
this work, we discuss the following topics:
1) Improved visibility and fidelity of entanglement for photon pairs generated
from droplet epitaxial GaAs QDs on (111)A with the help of temporal filtering.
The reasons responsible for the entanglement degradation associated with
spin-scattering with randomly oriented nuclei are also discussed.
2) Growth and characterization of telecom-band InAs QDs grown on InP(111)A
by droplet epitaxy. The photoluminescence spectra cover the telecom O (l~1.3
µm) and C (l~1.55 µm) bands. Single QD spectroscopy reveals FSS of ~20
µeV on average with random distribution of polarization angle, which suggests
a high possibility of finding QDs with near-zero FSS in a broad spectral range.
Small FSS (<4 µeV) is observed.
【問い合わせ先】先端フォトニクス材料ユニット樋口久美子（内線6796）

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