Enhanced optical and electric manipulation of a quantum gas of KRb molecules

<p>Polar molecules are an ideal platform for studying quantum information and quantum simulation\&nbsp;<span style="font-size: 13px;">due to their long-range dipolar interactions. However, they have many degrees of freedom\&nbsp;</span><span style="font-size: 13px;">at disparate energy scales and thus are difficult to cool. Ultracold KRb molecules near quantum\&nbsp;</span><span style="font-size: 13px;">degeneracy were first produced in 2008. Nevertheless, it was found that even when prepared in the\&nbsp;</span><span style="font-size: 13px;">absolute lowest state chemical reactions can make the gas unstable. During my PhD we worked to\&nbsp;</span><span style="font-size: 13px;">mitigate these limitations by loading molecules into an optical lattice where the tunneling rates,\&nbsp;</span><span style="font-size: 13px;">and thus the chemistry, can be exquisitely controlled. This setting allowed us to start using the\&nbsp;</span><span style="font-size: 13px;">rotational degree of freedom as a pseudo-spin, and paved the way for studying models of quantum\&nbsp;</span><span style="font-size: 13px;">magnetism such as the t-J model and the XXZ model. Further, by allowing molecules of two\&nbsp;</span><span style="font-size: 13px;">"spin"-states to tunnel in the lattice, we were able to observe a continuous manifestion of the quantum\&nbsp;</span><span style="font-size: 13px;">Zeno effect, where increased mobility counterintuitively suppresses dissipation from inelastic\&nbsp;</span><span style="font-size: 13px;">collisions. In a deep lattice we observed dipolar spin-exchange interactions, and we were able to\&nbsp;</span><span style="font-size: 13px;">elucidate their truly many-body nature. These two sets of experiments informed us that the filling\&nbsp;</span><span style="font-size: 13px;">fraction of the molecules in the lattice was only ~ 5\textendash10\%, and so we implemented a quantum\&nbsp;</span><span style="font-size: 13px;">synthesis approach where atomic insulators were used to maximize the number of sites with one K\&nbsp;</span><span style="font-size: 13px;">and one Rb, and then these "doublons" were converted to molecules with a filling of 30\%. Despite\&nbsp;</span><span style="font-size: 13px;">these successes, a number of tools such as high resolution detection and addressing as well as large,\&nbsp;</span><span style="font-size: 13px;">stable electric fields were unavailable. Also during my PhD I led efforts to design, build, test, and\&nbsp;</span><span style="font-size: 13px;">implement a new apparatus which provides access to these tools and more. We have successfully\&nbsp;</span><span style="font-size: 13px;">produced ultracold molecules in this new apparatus, and we are now applying AC and DC electric\&nbsp;</span><span style="font-size: 13px;">fields with in vacuum electrodes. This apparatus will allow us to study quantum magnetism in a\&nbsp;</span><span style="font-size: 13px;">large electric field, and to detect the dynamics of out-of-equilibrium many-body states.</span></p>
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University of Colorado Boulder
Advisors - JILA Fellows