Positions in Copenhagen
Currently all open positions at the University of Copenhagen were filled, but if you are interested you are always welcome to contact Jan Thomsen. As a member of our team you will work on our experimental setup in Copenhagen to develop a continuous superradiant optical clock operating on the narrow kHz line of Sr-88 (Tasks 2).
Two approaches to realizing the superradiant clock will be taken: one uses a 3D MOT in an optical cavity, while the other directs a cold beam of Sr atoms from a 2D MOT through an optical cavity, see figure.
The 3D MOT approach is based solely in Copenhagen and paves the way for understanding some of the complications we will face in the final system. The continuous atom-beam approach will be shared between Copenhagen and University of Amsterdam, whose expertise within bright cold atomic beams is extraordinary. Here you will construct a compact cold-atom source in Amsterdam and subsequently use it to generate a truly continuous superradiant clock in Copenhagen.
Two approaches to realizing the superradiant clock will be taken: one uses a 3D MOT in an optical cavity, while the other directs a cold beam of Sr atoms from a 2D MOT through an optical cavity, see figure.
The 3D MOT approach is based solely in Copenhagen and paves the way for understanding some of the complications we will face in the final system. The continuous atom-beam approach will be shared between Copenhagen and University of Amsterdam, whose expertise within bright cold atomic beams is extraordinary. Here you will construct a compact cold-atom source in Amsterdam and subsequently use it to generate a truly continuous superradiant clock in Copenhagen.
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Figure: Schematic of the UCPH machines configured for use in superradiant laser generation on the 7.4 kHz transition. a) Deflection and cooling stages in the mK beamline apparatus with spatial separation between cooling stages and lasing cavity. b) Overview of the atom-cavity interaction. Here the cold atoms propagate freely and enter the cavity in the excited state. By ensuring that the cavity coupling factor g exceeds decorence in the form of atomic dipole and cavity decays (Γ and κ) a superradiant lasing output may be achieved. c) Cavity setup in the case of the cyclically operated machine. Here only MOT cooling is used to cool the atoms, and quasi-continuous superradiant emission of laser light may be obtained when pumping in between cooling periods.
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The first system has been used to characterize cavity-enhanced spectroscopy and construct the first cavity QED operating clock. Here the TEM00 mode of an interaction enhancement cavity is overlapped with the 3D MOT and operates in a cyclic fashion. Superradiant emission by the atoms in the cavity mode will be demonstrated for the case of freely propagating atoms, which are not confined by an optical lattice. This simplification considerably reduces the necessary atom preparation time allowing millisecond repetition rates. Additionally the reduction of components in the system severely reduces the power consumption of such a system, complexity as well as the number of necessary lasers. Both the possibility of using a single-stage and a two-stage MOT will be investigated. The second approach uses a continuous Sr beam from a 2D MOT with a subsequent optical pumping stage in order to direct a beam of optically excited cold atoms through the lasing cavity. Excited state atoms entering the cavity mode will synchronize with the existing intracavity atoms. Thus an ensemble of atoms is continuously present in the cavity and preserves the phase information required for truly continuous superradiant emission with a linewidth at the Hz level. Modeling and data interpretation will be carried out jointly with the Torun, Innsbruck and Vienna teams.
This type of system can have a stability beyond any commercially available Hydrogen maser or atomic clock and can on a medium timescale (~6 years) lead to a competitive product. A core requirement of a commercial product is a compact version of the vacuum chamber of this clock, which we will develop together with the Amsterdam team including a yearlong stay of a Copenhagen PhD student at Amsterdam. We will build a compact, high-flux Sr beam source with an average velocity of <10m/s, axial temperature of ~1 mK and radial temperature <0.1mK. A cavity matching the source parameters will be designed together with the Vienna and Innsbruck teams and integrated with the beam source.
For more information please contact Jan Thomsen. To apply for a position send your CV.
Go to our group homepage.
This type of system can have a stability beyond any commercially available Hydrogen maser or atomic clock and can on a medium timescale (~6 years) lead to a competitive product. A core requirement of a commercial product is a compact version of the vacuum chamber of this clock, which we will develop together with the Amsterdam team including a yearlong stay of a Copenhagen PhD student at Amsterdam. We will build a compact, high-flux Sr beam source with an average velocity of <10m/s, axial temperature of ~1 mK and radial temperature <0.1mK. A cavity matching the source parameters will be designed together with the Vienna and Innsbruck teams and integrated with the beam source.
For more information please contact Jan Thomsen. To apply for a position send your CV.
Go to our group homepage.
