Beyond the Four-Level Model: Dark and Hot States in Quantum Dots Degrade Photonic Entanglement
Sprache des Titels:
Englisch
Original Kurzfassung:
Entangled photon pairs are essential for a multitude of quantum
photonic applications. To date, the best performing solid-state quantum emitters
of entangled photons are semiconductor quantum dots operated around liquidhelium
temperatures. To favor the widespread deployment of these sources, it is
important to explore and understand their behavior at temperatures accessible
with compact Stirling coolers. Here we study the polarization entanglement
among photon pairs from the biexciton?exciton cascade in GaAs quantum dots at
temperatures up to ?65 K. We observe entanglement degradation accompanied
by changes in decay dynamics, which we ascribe to thermal population and
depopulation of hot and dark states in addition to the four levels relevant for
photon pair generation. Detailed calculations considering the presence and characteristics of the additional states and phononassisted
transitions support the interpretation. We expect these results to guide the optimization of quantum dots as sources of highly
entangled photons at elevated temperatures.
Forschungs-