Positions at the University of Copenhagen (UCPH)
The position below has been filled.
Objectives:
At UCPH, we have recently demonstrated steady-state superradiant lasing on the kHz wide transition in Sr88. Through the iqClock project, we realized this on a narrow transition in cold strontium atoms and saw the clear behavior of a sub-linewidth emission spectrum. This cements the assumptions of superradiant laser performance expected from theoretical predictions and urges investigations of the fundamental linewidth, which is limited by the cavity Purcell rate. The DC will test the expected fundamental limitations experimentally with input on theoretical models from UIBK and TUW.
1) Atomic samples beyond the Purcell time
The DC will explore coherence times at the level of current commercial reference cavity systems by realizing lifetimes of the atomic sample beyond the gravitational transit time. This will be done by implementing a supply of cold atoms via the internal atomic degrees of freedom without significantly perturbing the lasing levels. Task 1: realize laser cooling on the (5s5p)3P2 - (5s6d)3D3 transition. Task 2: sustain atomic trapping on the metastable state for hundreds of ms. They will benefit from the experiences of UvA and CNRS (LTE) with advanced laser cooling techniques, and reduction of atom loss.
2) Probing the steady-state linewidth of a superradiant laser beyond the Fourier limitation
With long atomic lifetime the superradiant emission of the atoms can be probed beyond the Fourier limit to characterize technical linewidths and eventually identify the fundamental linewidth limits of the system. Task 3: achieve steady-state superradiant lasing in the presence of dark-state cooling. Task 4: reduce technical noise below the Purcell limit. Task 5: characterize superradiant lasing at the Purcell limit. Here, input from CNRS (LTE) on laser stability and clock accuracy will be a valuable tool to help the DC identify and overcome limitations.
At UCPH, we have recently demonstrated steady-state superradiant lasing on the kHz wide transition in Sr88. Through the iqClock project, we realized this on a narrow transition in cold strontium atoms and saw the clear behavior of a sub-linewidth emission spectrum. This cements the assumptions of superradiant laser performance expected from theoretical predictions and urges investigations of the fundamental linewidth, which is limited by the cavity Purcell rate. The DC will test the expected fundamental limitations experimentally with input on theoretical models from UIBK and TUW.
1) Atomic samples beyond the Purcell time
The DC will explore coherence times at the level of current commercial reference cavity systems by realizing lifetimes of the atomic sample beyond the gravitational transit time. This will be done by implementing a supply of cold atoms via the internal atomic degrees of freedom without significantly perturbing the lasing levels. Task 1: realize laser cooling on the (5s5p)3P2 - (5s6d)3D3 transition. Task 2: sustain atomic trapping on the metastable state for hundreds of ms. They will benefit from the experiences of UvA and CNRS (LTE) with advanced laser cooling techniques, and reduction of atom loss.
2) Probing the steady-state linewidth of a superradiant laser beyond the Fourier limitation
With long atomic lifetime the superradiant emission of the atoms can be probed beyond the Fourier limit to characterize technical linewidths and eventually identify the fundamental linewidth limits of the system. Task 3: achieve steady-state superradiant lasing in the presence of dark-state cooling. Task 4: reduce technical noise below the Purcell limit. Task 5: characterize superradiant lasing at the Purcell limit. Here, input from CNRS (LTE) on laser stability and clock accuracy will be a valuable tool to help the DC identify and overcome limitations.
