Engineering gauge fields: concept to reality
Here I present our experimental work on Bose-Einstein condensates, systems of ultra-cold charge neutral atoms at a
temperature of about 100 nano-Kelvin: about one billion times colder than room temperature. These condensates -- quantum gases -- are nearly perfect quantum mechanical systems, and here we demonstrate a technique by which these charge neutral particles behave as do charged particles do in magnetic and electric fields.Quantum gases are remarkable systems with a truly unprecedented level of experimental control. One application of this control is to engineer the strongly interacting many-particle systems usually associated with condensed matter physics. We use a pair of lasers to couple different quantum states of the atoms into new "laser-dressed" states which are imbued with an effective charge. In agreement with theory, we observe that above a critical coupling strength our BEC acts as a charged Bose gas in the presence of a conventional vec tor potential. Below this critical Raman coupling, the system
has well defined spin degrees of freedom and acts like a spin-1/2 Bose gas with spin-orbit coupling.