Position at Centre National de la Recherche Scientifique
Applications are now welcomed for the QuRIOUS PhD positions hosted by CNRS-LPL, CNRS-FEMTO and CNRS-LTE! To apply and find out more, please visit the LPL website, the FEMTO website and the LTE website.
Objectives:
We are developing a superradiant ytterbium laser experiment, with the objective of applications for time and frequency metrology. The project is now at an early stage, with an ytterbium MOT and a Fabry-Perot cavity that are still under characterization. The next stages will be to transport atoms inside the cavity and observe the first superradiant pulses with this experiment. The role of the DC will be to realize continuous superradiant operation.
1) Controlled superradiant lasing
Task 1: The DC will realize the controlled arrival of new atoms inside the cavity and state preparation to control the inversion population and sustain the superradiant pulse, similar to what has been demonstrated by UCPH on a broader transition. Task 2: The DC will repump atoms that have decayed to the ground state back to the 3P0. state for superradiant emission. Success will result in a semi-continuous emission of superradiance on ytterbium clock transition, limited by heating and lifetime of the atoms.
2) Continuous operation with sequential reloading
Task 3: The DC will prepare the sequential loading of two atomic ensembles inside the cavity, one of the ensemble being prepared while the other is lasing. Synchronization of the atomic dipoles between the two ensembles is one of the critical aspects of this task and will benefit from theory support from secondments in TUW. Success will result in the first continuous superradiant laser on a clock transition. Task 4: The DC will perform metrological characterization including stability measurements.
We are developing a superradiant ytterbium laser experiment, with the objective of applications for time and frequency metrology. The project is now at an early stage, with an ytterbium MOT and a Fabry-Perot cavity that are still under characterization. The next stages will be to transport atoms inside the cavity and observe the first superradiant pulses with this experiment. The role of the DC will be to realize continuous superradiant operation.
1) Controlled superradiant lasing
Task 1: The DC will realize the controlled arrival of new atoms inside the cavity and state preparation to control the inversion population and sustain the superradiant pulse, similar to what has been demonstrated by UCPH on a broader transition. Task 2: The DC will repump atoms that have decayed to the ground state back to the 3P0. state for superradiant emission. Success will result in a semi-continuous emission of superradiance on ytterbium clock transition, limited by heating and lifetime of the atoms.
2) Continuous operation with sequential reloading
Task 3: The DC will prepare the sequential loading of two atomic ensembles inside the cavity, one of the ensemble being prepared while the other is lasing. Synchronization of the atomic dipoles between the two ensembles is one of the critical aspects of this task and will benefit from theory support from secondments in TUW. Success will result in the first continuous superradiant laser on a clock transition. Task 4: The DC will perform metrological characterization including stability measurements.
Objectives: In CNRS (LPL), we have built a prototype for a superradiant laser based on a cold, effusive beam source. We want to achieve a continuously emitting superradiant laser and explore the working regimes of this rugged, atom beam configuration. Our approach uses the 1S0-3P1, 7 kHz-wide transition of strontium, and a cold atom beam source with tunable forward velocity from 10 to 100 m/s. We designed our apparatus to explore several regimes of interest, e.g., looking at the onset of atom-atom correlations close to the superradiant threshold.
1) CW superradiant lasing on Sr 1S0-3P1 transition with a cold atom beam
Task 1: The DC will finalize the construction of the apparatus, including cooling and guiding atoms toward the laser’s optical cavity. In particular, they will use the SWAP cooling technique to bring all incoming atoms into the narrow frequency band of the gain medium. Task 2: The DC will demonstrate the establishment of population inversion via the adiabatic transfer of atoms to the 3P1 state. For several of these tasks, we will benefit from collaborations with UvA, CNRS (FEMTO), UCPH, and UMK, which are also developing superradiant devices. Task 3: The DC will observe the first signs of collective interaction between the atoms and the light field in the cavity and ultimately detect a CW superradiant emission.
2) Characterizing the atom beam-based superradiant laser prototype for metrological applications
Task 4: The DC will investigate superradiant emission regimes (single mode, polychromatic, bi-stable, …) and the correlation properties of light and atoms. They will benefit from the theory support of TUW and numerical simulation efforts at UIBK to access and better understand these regimes and the effect of the atoms’ transit time and the injection angle. Supported by the secondment with INRIM, they will investigate atom-atom and atom-field correlations. Task 5: In collaboration with metrology experts at CNRS (LPL) and CNRS (LTE), the researcher will assess the metrological interest of atomic-beam CW superradiant lasers by comparison with the REFIMEVE network.
1) CW superradiant lasing on Sr 1S0-3P1 transition with a cold atom beam
Task 1: The DC will finalize the construction of the apparatus, including cooling and guiding atoms toward the laser’s optical cavity. In particular, they will use the SWAP cooling technique to bring all incoming atoms into the narrow frequency band of the gain medium. Task 2: The DC will demonstrate the establishment of population inversion via the adiabatic transfer of atoms to the 3P1 state. For several of these tasks, we will benefit from collaborations with UvA, CNRS (FEMTO), UCPH, and UMK, which are also developing superradiant devices. Task 3: The DC will observe the first signs of collective interaction between the atoms and the light field in the cavity and ultimately detect a CW superradiant emission.
2) Characterizing the atom beam-based superradiant laser prototype for metrological applications
Task 4: The DC will investigate superradiant emission regimes (single mode, polychromatic, bi-stable, …) and the correlation properties of light and atoms. They will benefit from the theory support of TUW and numerical simulation efforts at UIBK to access and better understand these regimes and the effect of the atoms’ transit time and the injection angle. Supported by the secondment with INRIM, they will investigate atom-atom and atom-field correlations. Task 5: In collaboration with metrology experts at CNRS (LPL) and CNRS (LTE), the researcher will assess the metrological interest of atomic-beam CW superradiant lasers by comparison with the REFIMEVE network.
Objectives:
1) Implementation of a spin-squeezed protocol interrogation sequence in a Sr optical lattice clock
One of the Sr optical lattice clocks (OLC) at CNRS (LTE) is equipped with a cavity-assisted non destructive readout of the transition probability. It is a shot-noise limited heterodyne scheme with homogeneous atom-cavity coupling. With this detection scheme, we have been able to observe quantum correlations between successive measurements. In a joint publication. with ICFO,, we proposed a Rabi-like interrogation protocol for the narrow clock transition that allows sub-Quantum Projection Noise (QPN) spectroscopy, with a maximum gain of 7.9 dB. Here, we propose to implement this protocol in our Sr OLC. Task 1: the DC will design and operate the clock sequence for the quantum protocol, and characterize its noise properties. Task 2: the DC will operate the clock with the sequence, and demonstrate sub-QPN spectroscopy. Task 3: The DC will investigate systematic effects induced by the QND probing.
2) Field-ready non-destructive readout in a Sr optical lattice clock
The non destructive detection already implemented at CNRS (LTE) has two practical limitations: first the mechanical stability is not optimized, which is not compatible with long, operational functioning of the clock, nor with field applications with high TRL; second, the vacuum level in the system is such that the lifetime of the trapped atoms is less than 1 s, which jeopardize any stability gain by recycling the atoms. We propose to implement a second version of the non-destructive detection in a new UHV system with an optimized mechanical design. Task 4: the DC will implement the detection hardware on the new UHV system, and show that it can be operated reliably over long periods. Task 5: the DC will demonstrate atom recycling, and characterize the associated gain in stability.
1) Implementation of a spin-squeezed protocol interrogation sequence in a Sr optical lattice clock
One of the Sr optical lattice clocks (OLC) at CNRS (LTE) is equipped with a cavity-assisted non destructive readout of the transition probability. It is a shot-noise limited heterodyne scheme with homogeneous atom-cavity coupling. With this detection scheme, we have been able to observe quantum correlations between successive measurements. In a joint publication. with ICFO,, we proposed a Rabi-like interrogation protocol for the narrow clock transition that allows sub-Quantum Projection Noise (QPN) spectroscopy, with a maximum gain of 7.9 dB. Here, we propose to implement this protocol in our Sr OLC. Task 1: the DC will design and operate the clock sequence for the quantum protocol, and characterize its noise properties. Task 2: the DC will operate the clock with the sequence, and demonstrate sub-QPN spectroscopy. Task 3: The DC will investigate systematic effects induced by the QND probing.
2) Field-ready non-destructive readout in a Sr optical lattice clock
The non destructive detection already implemented at CNRS (LTE) has two practical limitations: first the mechanical stability is not optimized, which is not compatible with long, operational functioning of the clock, nor with field applications with high TRL; second, the vacuum level in the system is such that the lifetime of the trapped atoms is less than 1 s, which jeopardize any stability gain by recycling the atoms. We propose to implement a second version of the non-destructive detection in a new UHV system with an optimized mechanical design. Task 4: the DC will implement the detection hardware on the new UHV system, and show that it can be operated reliably over long periods. Task 5: the DC will demonstrate atom recycling, and characterize the associated gain in stability.
