Ewch i’r prif gynnwys

Quantum coherence and carrier dynamics in colloidal nanostructures from dots to 1D and 2D materials

This research project is in competition for funding with one or more projects available across the EPSRC Doctoral Training Partnership (DTP). Usually the projects which receive the best applicants will be awarded the funding. Find out more information about the DTP and how to apply.

Colloidal nanostructures such as semiconductor quantum dots are relatively simple to manufacture, widely tuneable in shape and size and can be made of a large range of materials.

They are useful as optical biomarkers, wavelength converters on light emitting diodes, for solar energy applications, and quantum information processing. For all these applications, a better understanding of the light-matter interaction properties of these nanostructures is needed.

Background

The proposed project investigates the quantum coherent light-matter interaction regime and associated carrier dynamics of electrons and holes in novel colloidal structures developed to achieve a dephasing time limited solely by the radiative lifetime. A variety of different structures will be investigated towards this goal.

These include CdSe/ZnS platelets [Phys. Rev. B 91, 121302(R) (2015)], CdSe/CdS dots [Phys. Rev. Lett. 108, 087401 (2012)], InP/ZnSe dots, and perovskite quantum dots [Nano Lett. (2018) DOI 10.1021/acs.nanolett.8b03027]. These materials will be compared and contrasted with defect states in 1D materials (Carbon nanotubes) and 2D materials (transition metal dichalcogenides such as MoSe2 [Phys. Rev. B 96, 045407 (2017)]).

Notably, blinking and jitter of the optical transitions in all these materials, due to charge fluctuations in the environment, is currently limiting their applicability for quantum optics.

The origin of these effects will be determined in this project by using single emitter four-wave mixing and photoluminescence measurements, in order to reduce or eliminate these issues.

Project aims and methods

You will perform the measurements using, and further developing, our world-leading heterodyne-detected four-wave mixing setup described in our recent publications, as given below. You will develop experimental skills and knowledge in optics and lasers by using femtosecond lasers systems and a complex optical setup.

You will develop skills in programming by adapting the software to control the experiment. You will perform data analysis and modelling using the knowledge on the physical processes involved

The project outline plan is as follows:

  • Month 1-9: literature review, training on HFWM setup and data analysis.
  • Month 10-18: Dephasing and dynamics in Perovskite QDs – size and composition dependence. Publication.
  • Month 19-27: Carbon nanotubes. Publication. Month 28-33: Nanoplatelets and TMDCs (2D). Publication.
  • Month 35-38: thesis writing, submission,viva.

Goruchwylwyr

Wolfgang Langbein

Yr Athro Wolfgang Langbein

Head of Condensed Matter and Photonics

Email:
langbeinww@caerdydd.ac.uk
Telephone:
+44 (0)29 2087 0172

Co-supervisors

Professor Paolo Borri

Dr Egor Muljarov

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