PhD position in Attosecond physics in solids at King’s College London, UK

High Harmonic Generation in Solids (HHG-S) was first observed in ZnO crystal [1] and GaSe semi-conductor [2]. Recent results show that HHG-S can reach XUV range [3] towards the production attosecond pulses from solids. During HHG-S the strong laser field interaction with the solid creates an electron-hole pair via tunnel ionization. For single conductive band occupation, the electronic dynamic is understood as periodically modulated Block oscillations every half-cycle of the laser field, confining the process to attosecond timescale. This non-linear current produces high harmonics beyond the bandgap energy of the solid to a cut-off determined by the Bloch frequency. Due to the high density of solids, multiple electron-hole pairs’ attosecond dynamics may be involved in the process including inter-band transitions in the conductive bands for which little is known. In addition, the nature of the electron motion in the conductive band is not fully understood. In fact, as for HHG in gas phase where quantum-paths are clearly identified from the high harmonic far-field spectro-spatial distribution and their interferences [4], it is unknown how this quantum-paths picture may apply to HHG-S. Therefore, the questions we propose to answer in this project are:

What collective charge migrations take place in HHG-S?

Can we categorize these as electronic quantum-paths similarly, to gas high harmonics under the strong field approximation or shall a new nomenclature be defined?

Your project: To answer these questions, we propose to take a new route by investigating the process of High Harmonic Generation in two types of solid lattices:

HHG in periodic crystal lattice and HHG in aperiodic crystal lattice.

The project will explore beyond the monocrystal lattice, looking into quantum materials such as MOT-Insulator and metamaterials.

The project will take place within the Attosecond Quantum Physics Laboratory which is part of the Photonics & Nanotechnology division at KCL.

The activities involved in the project will include:

• Developing a new experimental set up for HHG-S beyond the current laboratory capability, included for instance control of phase changing in material.
• Investigation of proposed monocrystals and solid phase targets
• Gaining experimental skills linked to the use of strong laser field from CPA lasers and ultrashort pulses technology.
• Familiar yourself with theoretical tools in-house and the one available with our collaborators
• Development acquisition and analysis of experimental and theoretical data.
• Publications
• Attending conferences, workshops and summer schools.

Candidate requirements:

Candidates will be selected according to how well they meet the following criteria:

• A passion for research, and a desire to learn new skills
• Creativity and a collaborative spirit; the ability to work in a team
• Experience on experimental optical set-up, and ability to technical problem solving
• Ability to formulate and test hypotheses and to generate and analyze data
• Ability to effectively communicate research findings
• A background in optics, quantum mechanics, or light-matter interaction
• A first-class honours degree to second class honours upper division (2.1) in Physics, Mathematics, or related subjects
• The ability to clearly communicate your ideas to your colleagues and to people beyond our research team (please note that there are formal requirements on English language qualifications, which are detailed in https://www.kcl.ac.uk/study/postgraduate/apply/entry-requirements/english-language.aspx (Band D))

The following skills are desirable but not essential:

• An interdisciplinary degree, or experience outside of main degree topic
• Experience with working in a research environment
• Basic knowledge of laser physics, including polarization, fluence, pulsed laser.
• Basic knowledge of nonlinear optics, including strong-field physics and high-harmonic generation
• Ability to program in one or more programming language, such as Matlab, python, Julia, C++, etc…

Application Deadline: 1 May 2024

For informal enquiries and to discuss the scope of the project, please contact Amelle Zair amelle.zair@kcl.ac.uk

Further information >>

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