Doctoral student in chemical physics - Hiring in process/Finished, not possible to apply

Introduction and research environment 

This Ph.D. position will be focused on experimentally using ideas from cavity quantum optics to enable imaging of otherwise “dark” single molecules. Such “dark” molecules and transitions play a critical role for the electronic properties of molecular systems used in modern optoelectronics or as photovoltaic materials. 

It is enabled by the new framework Wallenberg Center for Quantum Technologies (WACQT), as a quantum sensing application. At Lund University, the position will be a collaboration between the divisions of Chemical Physics (Prof. Ivan Scheblykin) and Atomic Physics (Assistant Prof. Andreas Walther), combining expertise in both single molecule fluorescence spectroscopy and quantum optics in one team. The project will be challenging, technically and scientifically inspiring, and constitute an excellent educational environment for a graduate student. 

The Division of Chemical Physics (about 40 members) belongs to the Faculty of Science and it is among the leading laser spectroscopy laboratories in Europe. The Division utilizes advanced laser spectroscopy and microscopy methods including single molecule spectroscopy to study fundamental electron dynamics in various nano-systems from organic molecules and nanoparticles to semiconductors, see www.chemphys.lu.se. 

The Division of Atomic Physics at the Faculty of Engineering (LTH), Lund University, Sweden has a staff of over 50 researchers including guest researchers and graduate students. The research at the division is mainly based on the use of lasers, ranging from diode lasers to terawatt lasers at the High-Power Laser Facility. Areas of research include: interactions between intense laser-fields and matter, quantum optics, quantum information, spectroscopy, ultra-short pulses and bio-photonics. More information can be found at http://www.atomic.physics.lu.se/. 

As a country, Sweden offers one of the best employment conditions in the world for Ph.D. students, including a yearly salary of about €33000 and a strong social security net.  

Research focus and background information for this position 

To see the invisible – Quantum optics and fluorescence microscopy for detecting weakly emitting single molecules and functional nanoparticles 

Optical spectroscopy is one of the most powerful tools for monitoring electronic processes in molecular systems. Thanks to the pioneering work of W.E. Moerner and M. Orrit in the end of 1980s, today we can measure the optical response of an individual molecule or nanoparticle (Nobel prize in chemistry 2014).  

Detection of single molecules by luminescence is generally limited to systems with large radiative transition dipole moment (e.g. organic dyes) and large luminescence quantum yield. Unfortunately, the vast majority of molecular systems are difficult to detect at the single molecule level because their optical transitions are “dark”. This could either be because the transition dipole moment is very weak, like in e.g. triplet states or charge transfer states, or because the radiative transition is quenched by another far stronger non-radiative relaxation. These “dark” transitions play a critical role for the electronic properties of molecular systems used in modern optoelectronics or as photovoltaic materials. Therefore, detection of “dark” molecules at the single molecule level can open up a completely new perspective towards understanding of optoelectronic materials functioning beyond the ensemble averaged Picture. 

At the same time, cavity quantum electro dynamics (cavity QED) allows for so-called Purcell enhancement of the emission rate of a transition. This occurs in resonance with a high finesse cavity with a mode volume approaching that of a single wavelength cubed. In this regime, the vacuum mode density can be modified in such a way that the rate of spontaneous emission is increased, i.e. the natural lifetime is decreased. Such a system is currently being investigated for quantum information purposes, where emission enhancements of up to four orders of magnitude should be possible for good qubit systems like certain crystals doped with rare-earth ions. Emission enhancement is more challenging for single molecules, but several good candidates could be investigated during the project, for example modern pi-conjugated polymers designed for high-efficiency solar cells, natural light-harvesting complexes and semiconducting quantum dots. In addition, it appears possible to change the chemical interactions between molecules by the mere presence of the micro cavity, which is a very exciting and unexplored field of research that could also be targeted by our proposed setup. 

Entry requirements

A formal requirement for doctoral studies in physics is:

- a university degree on advanced level within a related field, such as a Master's degree in physics or equivalent, or substantial advanced course work at the Master level, or comparable, including an independent research Project. 

A person meets the specific admission requirements for third cycle studies in chemistry if he or she has:

- at least 90 credits of relevance to the subject, including at least 60 second-cycle credits, and a second-cycle degree project (Master level) of at least 30 credits of relevance to the field, or a second cycle degree (Master level) in a relevant field. 

Other requirements:

Good knowledge in speaking and writing English is a requirement. 

Basis of assessment

Selection to postgraduate studies is based on the expected ability to perform well in the studies. The evaluation of the ability to perform well is based primarily on the results of studies at the basic and advanced levels, in particular:

• Knowledge and skills relevant to postgraduate studies within the research area, such as a broad and thorough preparation in physics, optics, optical spectroscopy and fluorescence.
• Estimated ability to work independently and the ability to formulate and solve scientific questions. This ability can be established, for example, based on undergraduate research experiences, a Master's thesis or in a discussion of scientific problems during a possible interview.
• Skills in written and oral communication.
• Other experience relevant to postgraduate studies, such as professional experience.
• Good cooperation ability, drive, creativity and ability to organize and structure your work is considered as positive personal attributes
• Skills in programming (Labview, MATLAB, etc.)
• Previous experience of working in optical laboratories
• Knowledge of basic chemistry is a plus
• Answer to the assessment question below 

Assessment question:

• Light with a vacuum wavelength of 589 nm is entering an acrylic glass plate (PMMA type). What is the frequency and wavelength of the light inside the acrylic glass plate? – Write your answers in the cover letter, together with a brief explanation. 

Terms of employment

Only those admitted to third cycle studies may be appointed to a doctoral studentship. Third cycle studies at Lund University consist of full-time studies for 4 years. The position may also include teaching or technical/administrative duties at a level of at most 20% of full time. The position is then extended correspondingly, however not longer than corresponding to 5 years full time employment. Doctoral studentships are regulated in the Higher Education Ordinance (1998:80). 

Application procedure

Applications must contain a cover letter in which applicants describe themselves and their particular research interests and in particular in a non-generic way explains why they are interested in the present position. Applications must also include a CV, a copy of the applicant’s Master’s thesis (or a summary text if the thesis is not yet completed), contact details of at least two references, copies of grade certificates, and any other documents that the applicant wishes to refer to. In addition, the cover letter should address the Assessment question described above in the section Basis of assessment. 

Remarks

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