We propose an arresting scheme for simulating the famous Faraday effect in ultracold atomic gases. Inspired by the similarities between the light field and the bosonic atoms, we represent the light propagation in medium by the atomic transport in accompany of the laser-atom interaction. The artificial magneto-optic Faraday effect is readily signaled by the spin imbalance of atoms, with the setup of laser fields offering a high controllability for quantum manipulation. Our proposal can be realized with current experimental techniques of ultracold atoms, and is quite promising for exploring and investigating the magneto-optic Faraday effect and associated physics.
We propose an arresting scheme for simulating the famous Faraday effect in ultracold atomic gases. Inspired by the similarities between the light field and the bosonic atoms, we represent the light propagation in medium by the atomic transport in accompany of the laser-atom interaction. The artificial magneto-optic Faraday effect is readily signaled by the spin imbalance of atoms, with the setup of laser fields offering a high controllability for quantum manipulation. Our proposal can be realized with current experimental techniques of ultracold atoms, and is quite promising for exploring and investigating the magneto-optic Faraday effect and associated physics.
Abstract We propose an arresting scheme for emulating the famous Faraday effect in ultracold atomic gases. Inspired by the similarities between the light field and bosonic atoms, we represent the light propagation in medium by the atomic transport in accompany of the laser-atom interaction. An artificial magneto-optic Faraday effect (MOFE) is readily signaled by the spin imbalance of atoms, with the setup of laser fields offering a high controllability for quantum manipulation. The present scheme is really feasible and can be realized with existing experimental techniques of ultracold atoms. It generalizes the crucial concept of the MOFE to ultracold atomic physics, and opens a new way of quantum emulating and exploring the MOFE and associated intriguing physics.
Magneto-optic effect is a fundamental but broad concept in magnetic mediums. Here we propose an arresting scheme for its quantum emulation using ultracold atoms. By representing the light-medium interaction in the quantum emulation manner, the artificial magneto-optic effect emerges under an entirely different mechanism from a conventional picture. The underlying polarization state extracted in the synthetic dimension displays a different response to various experimental setups. Notably, the magneto-optic rotation is related to the bulk topology in synthetic dimensions, and thus provides an unambiguous evidence for the desired topological magneto-optic effect, which has not been developed hitherto in ultracold atoms. This scheme is simple and feasible based on current experimental techniques. Implementation of the scheme is able to offer an intriguing platform for exploring topological magneto-optic effects and associated physics.
Abstract Magneto-optical effect is a fundamental but broad concept in magnetic mediums. Here we propose a scheme for its quantum emulation using ultracold atoms. By representing the light-medium interaction in the quantum-emulation manner, the artificial magneto-optical effect emerges under an entirely different mechanism from the conventional picture. The underlying polarization state extracted in the synthetic dimension displays a different response to various experimental setups. Notably, the magneto-optical rotation is related to the bulk topology in synthetic dimensions, and thus provides an unambiguous evidence for the desired topological magneto-optical effect, which has not been developed hitherto in ultracold atoms. This scheme is simple and feasible, and can be realized by current experimental techniques. The implementation of the scheme is able to offer an intriguing platform for exploring topological magneto-optical effects and associated physics.
Ultra-cold quantum gases subjected to light-induced synthetic gauge potentials have become an emergent field of theoretical and experimental studies. Because of the novel application of two-photon Raman transitions, ultra-cold neutral atoms behave like charged particles in magnetic field. The Raman coupling naturally gives rise to an effective spin-orbit interaction which couples the atom’s center-of-mass motion to its selected pseudo-spin degrees of freedom. Combined with unprecedented controllability of interactions, geometry, disorder strength, spectroscopy, and high resolution measurement of momentum distribution, etc., we are truly in an exciting era of ful- filling and going beyond Richard Feynman’s vision of realizing quantum simulators to better understand the quantum mechanical nature of the universe, manifested immensely in the ultra-cold regimes. In this dissertation, we present a collection of theoretical progresses made by the doctoral candidate and his colleagues and collaborators. From the past few years of work, we mainly address three aspects of the synthetic spin-orbit and light field induced coupling in ultracold quantum gases: a) The ground-state physics of single- particle system, two-body bound states, and many-body systems, all of which are subjected to spin-orbit coupling originated from synthetic gauge potentials; b) The symmetry breaking, topological phase transition and quench dynamics, which are conveniently offered by the realized experimental setup; c) The proposal and impli- cations of light field induced dynamical spin-orbit coupling for atoms inside optical cavity. Our work represents an important advancement of theoretical understanding to the active research frontier of ultra-cold atom physics with spin-orbit coupling.
In this habilitation-thesis a collection of 14 experiments is presented. In these experiments we have developed and used novel techniques to control ultracold gases on the quantum level. In brief, Bose-Einstein condensates (BEC) and degenerate Fermi gases of laser-cooled alkali atoms are subjected to specially designed optical and magnetic fields. The fields influence in a coherent way the behavior, properties and dynamics of the gases. On this basis we developed tools to prepare, coherently manipulate, and analyze pre-defined quantum states. With this high level of control, it was possible to investigate interesting physics phenomena, and we were able to achieve several breakthroughs in the field of ultracold atoms. Highlights of our experimental results include the demonstration of phase engineering of a BEC wavefunction where we created solitons in a BEC and studied their propagation. In another experiment we constructed a spatially resolved matter wave interferometer with which we mapped out the phase distribution on a condensate. Illuminating the BEC with a periodic pattern, i.e. an optical lattice, allowed us to study solid states physics phenomena. In a second set of experiments we demonstrated optically tuning of the interaction between atoms with optical Feshbach resonances. Employing either magnetically tunable Feshbach resonances or laser radiation, we were able to produce ground state molecules in well defined quantum states. This led to the production of the first molecular BEC. By tuning the coupling of atom pairs in a Fermi gas of atoms, we could for the first time investigate the so-called BEC-BCS crossover which describes the continuous change from a BEC superfluid to a Bardeen-Cooper Schrieffer (BCS) superfluid. Due to the excellent control on the quantum level, the developed cold atom techniques open up intriguing prospects for future applications and experiments. They represent a general tool box to investigate fundamental physical phenomena in a pure and undisturbed environment. In the future, cold atoms might serve as a testing ground for fundamental theories or as quantum simulators for complex systems.
Abstract : It is well known that ultracold atoms (T < 1 milliKelvin) are promising candidates for nextgeneration inertial sensors and magnetometers. An interferometer measures accelerations and rotations in much the same way as does a laser-based interferometer, except that the recorded interferograms are due to matter wave interference rather than optical interference. Large laboratory-based atom interferometers using thermal atom beams have demonstrated unparalleled performance, but the most promising path to making such technology practical is to use ultracold atoms: unlike room temperature atoms, cold atoms can be guided along controlled trajectories, analogous to fiber optics for light. The roles of matter and light are reversed - whereas material guides photons in fiber optics, photons guide atoms in atom optics. To realize high sensitivities with cold atoms, we must: (1) obtain a large flux of cold atoms and (2) guide atoms coherently in atom waveguides. Our group is working on these issues using optical techniques with cold atoms derived from a magneto-optical trap that contains roughly 108 rubidium atoms at a temperature of 10 muK and density of 10(11) atoms/cm(3).