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

Outline

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.

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.

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 & 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

References: 

M.A. Becker et al., Nano Lett. (2018) DOI 10.1021/acs.nanolett.8b03027

L. Scarpelli et al., Phys. Rev. B 96, 045407 (2017) DOI 10.1103/PhysRevB.96.045407

A. Naeem et al. Phys. Rev. B 91, 121302(R) (2015) DOI 10.1103/PhysRevB.91.121302

What is funded

Self-Funded PhD Students Only

This PhD position is opening for self-funded student only, which means the candidate with own funding to cover the living cost and tuition fees will be considered.

Duration

Feasibility of completion within 4 years: 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 & TMDCs (2D). Publication. Month 35-38: thesis writing, submission,viva

Eligibility

Candidates should hold a good bachelor’s degree (first or upper second-class honours degree) or a MSc degree in Physics or a related subject. Applicants whose first language is not English will be required to demonstrate proficiency in the English language (IELTS 6.5 or equivalent).

How to Apply

Applicants should submit an application for postgraduate study via the Cardiff University webpages (https://www.cardiff.ac.uk/study/postgraduate/research/programmes/programme/physics-and-astronomy) including:

• an upload of your CV

• a personal statement/covering letter

• two references

• Current academic transcripts

Applicants should select Doctor of Philosophy, with a start date of January 2021

In the research proposal section of your application, please specify the project title and supervisors of this project and copy the project description in the text box provided. In the funding section, please select the ’self -funding’ option.