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PhD candidate Charged Quantum Impurities in a Fermi Sea

Faculty of Science – Institute of Physics

PhD candidate Charged Quantum Impurities in a Fermi Sea
Publication date 21 January 2019
Closing date 1 March 2019
Level of education Master's degree
Hours 38 hours per week
Salary indication €2,325 to €2,972 gross per month
Vacancy number 19-037

We are looking for a highly-motivated student for performing state-of-the-art atomic physics experiments.

The hybrid atom-ion quantum systems lab, headed by Dr Rene Gerritsma, is part of the Quantum Gases and Quantum Information (QGQI) cluster at the University of Amsterdam (UvA). The group studies mixtures of ultracold atom gases that are interacting with trapped ions. The main focus of the group is to study the quantum dynamics of these systems while at the same time developing technology for emerging quantum applications, such as quantum computing and simulation.

Project description

In the project you will answer an intriguing question in the laboratory: What happens when we immerse a single spin or a single quantum harmonic oscillator into a Fermi sea or a Bose-Einstein condensate?  

An impurity interacting with a quantum bath is a nontrivial many-body model system with broad relevance to condensed matter. A prominent example from condensed matter physics is an electron in an ionic crystal lattice that forms a quasiparticle by coupling to phonons. The phonon-dressed electron is known as a polaron and plays a central role in our understanding of many quantum systems. Other examples include that of a single spin interacting with a bath of spins - known as the central spin problem -  or a single quantum harmonic oscillator that is coupled to an environment. These systems could shed light on the fuzzy boundary between classical and quantum physics and may prove to be of fundamental importance when considering the practical applicability of quantum technology such as quantum computers. This is because a clear understanding of quantum systems coupled to increasingly complex (quantum) environments will be indispensable for building quantum technologies where such couplings are unavoidable.

You will use a single trapped Yb+ ion as impurity, immersed in a bath of Li atoms. Trapped ions allow for full control over their internal and motional degrees of freedom at the single ion level. The development of these techniques made it possible to perform experiments that were previously considered to be purely hypothetical (Gedanken experiments), such as the creation of small Schrödinger cat states (2012 Nobel Prize of David Wineland). You will use these techniques to study the coupling of the spin of a single ion, or its quantized motion in the harmonic potential, to a quantum bath of Li atoms that are as cold as 100 nK. Using tools developed in ultracold atomic physics, we can change the bath from a weakly interacting degenerate Fermi gas, via a strongly interacting gas at unitarity, to a Bose-Einstein condensate of weakly bound Li2 molecules. We will also be able to control the impurity-bath interaction by laser-induced tuning of the polarizability of the atomic cloud by weak coupling to Rydberg states.

Once we have understood the quantum physics of the single impurity-bath system, we can use it in a number of applications. One obvious extension is to increase the number of impurities and immerse a crystal of trapped ions into the atomic cloud. Now, the harmonic oscillators take the form of soundwaves that can couple to the atomic bath. Since the atoms are fermions, the system resembles a natural crystalline solid and could therefore be used as a quantum simulator of such solids. Finally, the cold atoms could be used to keep the ion crystal very cold. Ion crystals are presently the most accurate prototype quantum computers available and the atomic gas may allow to cool (and therefore improve) the system further.

Relevant references:

  • U. Bissbort et al., Phy. Rev. Lett. 111, 080501 (2013)
  • H. Fürst et al., Phys. Rev. A 98, 012713 (2018)
  • N.V. Ewald et al., arXiv:1809.03987 (2018)


You hold a MSc. in Physics or Physical Chemistry and are requested to motivate why you apply for the position and to supply a CV. Applicants with a degree in Chemistry are also requested to detail their affinity with atomic physics and motivation for pursuing a PhD in experimental physics.

Other skills/experiences/documents that would benefit your application are:

  • previous laboratory experience in an atomic physics lab;
  • working knowledge of a programming language (C++, Python or equivalent);
  • excellent English and oral and written communication skills;
  • scientific publications.

Further information

For informal enquiries about the position please direct your questions to:


The appointment will be on a temporary basis for a period of 4 years (initial appointment will be for a period of 18 months and after satisfactory evaluation it can be extended for a total duration of 4 years) and should lead to a dissertation (PhD thesis). We will draft an educational plan that includes attendance of courses and (international) meetings. We expect you to assist in teaching of undergraduates.

Based on a full-time appointment (38 hours per week) the gross monthly salary will range from €2,325 in the first year to €2,972 in the last year. The Collective Labour Agreement for Dutch Universities is applicable. Favourable tax agreements may apply to non-Dutch applicants.

Job application

The UvA is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. We value a spirit of enquiry and endurance, provide the space to keep asking questions and cherish a diverse atmosphere of curiosity and creativity.

Applications should be submitted through the link below. All applications should include:

  • a cv;
  • a motivation letter that explains why you have chosen to apply for this specific position with a statement of your research experience and interests and how these relate to this project;
  • title and summary of your Master thesis.

Applications will be processed on a rolling basis and the position will remain open until a suitable candidate has been identified (formal closing date: 1 March 2019). #LI-DNP

No agencies please

Apply now