This paper presents an experimental and theoretical study of laser cooling in a standing wave in the presence of a small transverse magnetic field (Magnetically Assisted Sisyphus Effect: MASE). The analysis is worked out for a Jg=1 to Je=1 transition corresponding to the experiment performed on the $2^{3}\rm S_{1}\longleftrightarrow 2^{3}\rm P_{1}$ transition of metastable helium. In this situation, MASE has an effect opposed to the usual Doppler cooling effect, i.e. it produces heating for a negative detuning. Depending on the various parameters, the competition between MASE and Doppler cooling, which act on different velocity ranges, leads to interesting new effects, such as a bistable force. The velocity dependence of the total force is calculated, using a semi-classical approach. A second theoretical treatment, where the atomic motion is quantized, is used to study the time evolution of the velocity distribution. The results of these calculations are compared to experimental observations.This paper presents an experimental and theoretical study of laser cooling in a standing wave in the presence of a small transverse magnetic field (Magnetically Assisted Sisyphus Effect: MASE). The analysis is worked out for a Jg=1 to Je=1 transition corresponding to the experiment performed on the $2^{3}\rm S_{1}\longleftrightarrow 2^{3}\rm P_{1}$ transition of metastable helium. In this situation, MASE has an effect opposed to the usual Doppler cooling effect, i.e. it produces heating for a negative detuning. Depending on the various parameters, the competition between MASE and Doppler cooling, which act on different velocity ranges, leads to interesting new effects, such as a bistable force. The velocity dependence of the total force is calculated, using a semi-classical approach. A second theoretical treatment, where the atomic motion is quantized, is used to study the time evolution of the velocity distribution. The results of these calculations are compared to experimental observations.

Journal de Physique IIDec 1, 199323 citations

Cavity Doppler cooling in three dimensions

Vladan Vuletić

Quantum Electronics and Laser Science ConferenceMay 6, 20010 citations

Sub-Doppler Laser Cooling

Princeton University Press eBooksDec 13, 20100 citations

Optical forces on neutral atoms in the presence of fluctuating laser fields: numerical analysis

Forough Bozorgzadeh, Masoud Yousefi, Mohsen Akbari

Abstract Doppler cooling of 88Sr atoms is studied in the presence of off-resonant red-detuned fluctuating laser fields. Using a semi-classical approach, we show that the relevant physical quantities in the cooling process, such as optical forces, the damping coefficient, Doppler temperature, and atom number in the trap, are strongly affected by the laser amplitude and phase fluctuations. We find that the Doppler cooling limit is higher than the predicted Doppler theory for non-fluctuating lasers. This implies an additional heating mechanism exists due to the laser fluctuations. Furthermore, our numerical analysis shows that the effect of laser power stability on reducing the number of trapped atoms in a magneto-optical trap is more substantial than the effect of laser linewidth.Abstract Doppler cooling of 88Sr atoms is studied in the presence of off-resonant red-detuned fluctuating laser fields. Using a semi-classical approach, we show that the relevant physical quantities in the cooling process, such as optical forces, the damping coefficient, Doppler temperature, and atom number in the trap, are strongly affected by the laser amplitude and phase fluctuations. We find that the Doppler cooling limit is higher than the predicted Doppler theory for non-fluctuating lasers. This implies an additional heating mechanism exists due to the laser fluctuations. Furthermore, our numerical analysis shows that the effect of laser power stability on reducing the number of trapped atoms in a magneto-optical trap is more substantial than the effect of laser linewidth.

Communications in Theoretical PhysicsNov 1, 20221 citation

Laser cooling of atoms : Monte-Carlo wavefunction simulations

Renaud Chrétien

The purpose of our master thesis is to present an original synthesis of various works dealing with the Monte-Carlo wavefunction (MCWF) method in quantum optics and its applications to laser cooling of atoms with a particular focus on Doppler and Sisyphus cooling mechanisms. We introduce the MCWF method which is used to solve master equations describing the dynamics of open quantum systems in quantum optics. This method turns out to be much more efficient than a method based on the full integration of the density matrix. We perform laser cooling simulations in 1D both with a classical and a quantum treatment of the atomic centre-of-mass motion and investigate Doppler and Sisyphus cooling. Our numerical results turn out to be in very good agreement with those predicted by semiclassical theories, except for large detuning and/or low intensity laser where semiclassical theories fail. For such cases, our method provides a good alternative and predicts temperatures much larger than the recoil temperature. Finally, we also consider a classical treatment of the centre-of-mass motion and we compare the subsequent results with those obtained with a full quantum approach.The purpose of our master thesis is to present an original synthesis of various works dealing with the Monte-Carlo wavefunction (MCWF) method in quantum optics and its applications to laser cooling of atoms with a particular focus on Doppler and Sisyphus cooling mechanisms. We introduce the MCWF method which is used to solve master equations describing the dynamics of open quantum systems in quantum optics. This method turns out to be much more efficient than a method based on the full integration of the density matrix. We perform laser cooling simulations in 1D both with a classical and a quantum treatment of the atomic centre-of-mass motion and investigate Doppler and Sisyphus cooling. Our numerical results turn out to be in very good agreement with those predicted by semiclassical theories, except for large detuning and/or low intensity laser where semiclassical theories fail. For such cases, our method provides a good alternative and predicts temperatures much larger than the recoil temperature. Finally, we also consider a classical treatment of the centre-of-mass motion and we compare the subsequent results with those obtained with a full quantum approach.

Jun 23, 20143 citations

Sub-Doppler cooling of trapped ions

G. Birkl, John A. Yeazell, R. Rueckerl +1 more

Quantum Electronics and Laser Science ConferenceMay 22, 19950 citations

2^{3}\rm S_{1}\longleftrightarrow 2^{3}\rm P_{1}

transition of metastable helium. In this situation, MASE has an effect opposed to the usual Doppler cooling effect, i.e. it produces heating for a negative detuning. Depending on the various parameters, the competition between MASE and Doppler cooling, which act on different velocity ranges, leads to interesting new effects, such as a bistable force. The velocity dependence of the total force is calculated, using a semi-classical approach. A second theoretical treatment, where the atomic motion is quantized, is used to study the time evolution of the velocity distribution. The results of these calculations are compared to experimental observations.