Wave packet interference experiments for the investigation of ultrafast dynamics and decoherence effects on the attosecond time scale

Context. Wave packet interferometry of electronic transitions using ultrafast, broadband lasers is a powerful technique to reveal the full quantum dynamics of an excited system. Coherent couplings and related decoherence and dissipation dynamics, as well as entanglement in many-body systems can be studied even down to attosecond time scales. In this project, based on our experience on wave packet interferometry and multidimensional coherent methods (L. Bruder, et al., Nat. Comm. 9, 4823 (2018), L. Bruder, et al., PCCP 21, 2276 (2019)), wave packet interferometry will be employed to study coherent couplings and related decoherence and dissipation dynamics, and, in particular to apply corresponding methods to attosecond pulses. These are created in the extreme ultraviolet and X-ray spectral range by the process of high-order harmonics generation in gases. A broadband electronic superposition of states can be achieved by irradiating atoms and molecules with such coherent broadband pulses. Quantum beating ranging from a few hundreds of attoseconds up to a few femtoseconds are expected for excitations in the extreme ultraviolet range. The observation of such beating is limited by decoherence effects, whose relevance strongly depends on the environment in which the system is placed. In particular, we will investigate the feasibility of experimental methods for the reconstruction (amplitude and phase) of the different components of an electronic wave packet created by an attosecond pulse. Using as target system helium atoms and helium clusters, we aim at investigating how the interaction with the environment affects the quantum beating between the different states and how decoherence effects depend on the size (number of atoms) of clusters.
The experimental approach for the analysis of the electronic wave packet will be based on the measurement of the photoelectron spectrum created by the single and multiple-photon ionization induced by an intense infrared pulse on the coherent quantum superposition of states (J. Mauritsson et al. Phys. Rev. Lett. 105,053001 (2010)). Strategies for a complete read-out (amplitude and phase simultaneously) of the electronic wave packets will be developed.

Supervisor: Prof. Frank Stienkemeier

Eligibility criteria and requirements
The applicant should be a highly motivated early stage researcher with a Master degree in Physics. A solid background in the atomic, molecular and optical physics as well as experience in laser and vacuum technology is needed.

QUSTEC programme follows MSCA eligibility criteria: Required level of experience is ‘Early Stage Researcher’ according to the definition in the work programme of the 2018-2020 Marie Skłodowska-Curie actions: Applicants must, at the date of the respective call deadline of QUSTEC, be in the first four years (full-time equivalent research experience) of their research careers and have not yet been awarded a doctoral degree. Mobility criterion: The applicants must not have resided or carried out their main activity (work, studies, etc.) in the country of the future host organisation for more than 12 months in the 3 years immediately before the call deadline of QUSTEC. Short stays such as holidays are not taken into account. For refugees under the Geneva Convention, the refugee procedure (i.e. before refugee status is conferred) will not be counted as a period of residence/activity in the country of the host organisation.

Application procedure:
The proposed PhD position is part of the QUSTEC doctoral programme, funded by the MSCA-COFUND scheme, coordinated by Eucor – The European Campus, and implemented by Eucor partner institutions (University of Basel, University of Freiburg, University of Strasbourg and the Karlsruhe Institute of Technology), which are joined by IBM-Research in Zurich, and WMI in Munich. The complete description of the programme as well as the full list of research topics can be found on the project website. Candidates are encouraged to indicate two additional research topics that they are interested in, in addition to the selected PhD offer, from the list of available topics that can be found on the programme website.
Please, submit your application exclusively via an electronic submission system.
The deadline for applications is September 30, 2020 at 17.00 (Brussels time)

Before submitting the application, please contact the scientific supervisors (obligatory). For any other issues, please address your request to the programme coordinator (contact details can be found in the Guide for applicants).

Working conditions: All PhD candidates will be employed under a 4-years full-time PhD contract following the national regulations.