We report on our progress in the construction of a machine capable of cooling Strontium atoms to ultra-cold temperatures, to interact collectively with the modes of a ring cavity. We present the first observation of a novel manifestation of saturation-induced optical bistability in a resonantly pumped optical ring cavity, interacting with a narrow atomic transition cloud. The bistability emerges, above a critical pump rate, as an additional peak in the cavitys normal-mode spectra near the atomic resonance. The new regime addressed for our machine takes advantage of the narrow atomic transition enabling the observation of bistability in a strong resonant regime where the atoms couple collectively to the cavity.
We report on our progress in the construction of a machine capable of cooling Strontium atoms to ultra-cold temperatures, to interact collectively with the modes of a ring cavity. We present the first observation of a novel manifestation of saturation-induced optical bistability in a resonantly pumped optical ring cavity, interacting with a narrow atomic transition cloud. The bistability emerges, above a critical pump rate, as an additional peak in the cavitys normal-mode spectra near the atomic resonance. The new regime addressed for our machine takes advantage of the narrow atomic transition enabling the observation of bistability in a strong resonant regime where the atoms couple collectively to the cavity.
We report on our progress in the construction of a machine capable of cooling Strontium atoms to ultra-cold temperatures, to interact collectively with the modes of a ring cavity.We present the first observation of a novel manifestation of saturation-induced optical bistability in a resonantly pumped optical ring cavity, interacting with a narrow atomic transition cloud.The bistability emerges, above a critical pump rate, as an additional peak in the cavity's normal-mode spectra near the atomic resonance.The new regime addressed for our machine takes advantage of the narrow atomic transition enabling the observation of bistability in a strong resonant regime where the atoms couple collectively to the cavity.
We report on the observation of a novel manifestation of saturation-induced optical bistability in a resonantly pumped optical ring cavity interacting strongly with a cloud of atoms via a narrow atomic transition. The bistability emerges, above a critical pump rate, as an additional peak in the cavity's normal mode spectrum close to atomic resonance. This third transmission peak is usually suppressed due to strong resonant absorption, but in our experiment it is visible because of the linewidth of the atomic transition being much smaller than that of the cavity, which sets the experiment into the bad-cavity regime. Relying on complete saturation of the transition, this bistability has a quantum origin and cannot be mimicked by a classical material presenting a nonlinear refraction index. The appearance of the central peak in addition to the normal modes is predicted by a semi-classical model derived from the Tavis-Cummings Hamiltonian from which we derive a bistability phase diagram that connects our observations with former work on optical bistability in the good cavity regime. The phase diagram reveals several so far unexplored bistable phases.
Abstract We report on the observation of a novel manifestation of saturation-induced optical bistability in a resonantly pumped optical ring cavity interacting strongly with a cloud of atoms via a narrow atomic transition. The bistability emerges, above a critical pump rate, as an additional peak in the cavity’s normal mode spectrum close to atomic resonance. This third transmission peak is usually suppressed due to strong resonant absorption, but in our experiment it is visible because of the linewidth of the atomic transition being much smaller than that of the cavity, which sets the experiment into the bad-cavity regime. Relying on complete saturation of the transition, this bistability has a quantum origin and cannot be mimicked by a classical material presenting a nonlinear refraction index. The appearance of the central peak in addition to the normal modes is predicted by a semi-classical model derived from the Tavis–Cummings Hamiltonian from which we derive a bistability phase diagram that connects our observations with former work on optical bistability in the good cavity regime. The phase diagram reveals several so far unexplored bistable phases.
This thesis describes the first steps to fulfill the main objective of our project: the development of a gravimetry system based on the continuous monitoring of Bloch oscillations performed by ultra-cold strontium atoms. The realization of this project comprises three main stages: the first stage consists in obtaining a magneto-optical trap in the broad transition of 461 nm of strontium, the second stage is the transfer to a magneto-optical trap in the narrow intercombination line of 689 nm, and finally the third stage is the monitoring of Bloch oscillations of the cloud of atoms in a ring cavity. This work details the first stage of the project, the creation of an experimental apparatus which produces ultra-cold strontium atoms in the transition of 461 nm, as well as the characterization of the cloud of atoms, temperature, size, number of atoms, etc. For this project, a new experimental apparatus has been designed and realized. It involves an ultra-high vacuum system, magnetic field sources, laser systems and optical instruments which are required for cooling, trapping and repumping strontium atoms. A novel feature is the implementation of a transversely loaded two-dimensional magneto-optical trap, which serves as a source of a cold strontium atomic beam. A loading rate of the atomic beam into a nearby three-dimensional magneto-optical trap exceeding 105 s-1 for the 88Sr isotope at a moderate dispenser temperature of 600 °C are reported. The temperature of the cloud is about 4 mK and its size 0.3 mm, these characteristics suggest that the state of the atomic trap is in optimal conditions to make the transfer to the optical magneto trap in the intercombination line and thus continue with the second stage of the project.
We experimentally study the interaction between a cold-atom cloud and many longitudinal modes of a high-quality Fabry-Perot cavity, by measuring signatures of collective light shifts in the cavity transmission spectrum of an optical frequency comb probe. Using a resonator coupled to more than 10 5 intracavity atoms, we detect significant shifts of ∼ 100 cavity modes simultaneously, which is a direct manifestation of physics beyond the hitherto explored regime of cavity-cold atom interaction with only single or few longitudinal modes at a time. For the cavity mode closest to the atomic resonance, we demonstrate a bistability in the transmission spectrum, arising due to a combined coupling of the cloud to an external pump laser and a cavity mode probed by the optical frequency comb. These results provide a first step toward deeper exploration of multifrequency cavity quantum electrodynamics, where ultrashort pulsed sources could be used for optical manipulation, cooling, and entanglement of cold atoms in a resonator.
This thesis describes the first steps to fulfill the main objective of our project: the development of a gravimetry system based on the continuous monitoring of Bloch oscillations performed by ultra-cold strontium atoms.The realization of this project comprises three main stages: the first stage consists in obtaining a magneto-optical trap in the broad transition of 461 nm of strontium, the second stage is the transfer to a magneto-optical trap in the narrow intercombination line of 689 nm, and finally the third stage is the monitoring of Bloch oscillations of the cloud of atoms in a ring cavity.This work details the first stage of the project, the creation of an experimental apparatus which produces ultra-cold strontium atoms in the transition of 461 nm, as well as the characterization of the cloud of atoms, temperature, size, number of atoms, etc.For this project, a new experimental apparatus has been designed and realized.It involves an ultra-high vacuum system, magnetic field sources, laser systems and optical instruments which are required for cooling, trapping and repumping strontium atoms.A novel feature is the implementation of a transversely loaded two-dimensional magneto-optical trap, which serves as a source of a cold strontium atomic beam.A loading rate of the atomic beam into a nearby three-dimensional magneto-optical trap exceeding 10 5 s -1 for the 88 Sr isotope at a moderate dispenser temperature of 600 • C are reported.The temperature of the cloud is about 4 mK and its size 0.3 mm, these characteristics suggest that the state of the atomic trap is in optimal conditions to make the transfer to the optical magneto trap in the intercombination line and thus continue with the second stage of the project.