A quantum gas of polar molecules in an optical lattice

<p>Ultracold polar molecules, because of their long-range, spatially anisotropic interactions, are\&nbsp;<span style="line-height: 1.6em;">a new quantum system in which to study novel many-body phenomena. In our lab, we have produced\&nbsp;</span><span style="line-height: 1.6em;">the first quantum gas of <sup>40</sup>K<sup>87</sup>Rb polar molecules. These molecules were found to undergo\&nbsp;</span><span style="line-height: 1.6em;">exothermic chemical reactions, and this led to interesting studies of chemistry near absolute zero.\&nbsp;</span><span style="line-height: 1.6em;">By creating the molecules at individual sites of a 3D optical lattice, we completely suppress these\&nbsp;</span><span style="line-height: 1.6em;">chemical reactions, and the polar molecule gas becomes stable and lives for tens of seconds. This\&nbsp;</span><span style="line-height: 1.6em;">thesis documents our efforts to explore coherent, many-body phenomena resulting from long-range\&nbsp;</span><span style="line-height: 1.6em;">dipolar interactions in the lattice. By encoding a spin-1=2 system in the rotational states of the\&nbsp;</span><span style="line-height: 1.6em;">molecules, we were able to realize spin-exchange interactions based on a spin Hamiltonian, which is\&nbsp;</span><span style="line-height: 1.6em;">one of the first steps in studying quantum magnetism with polar molecules. While this study was\&nbsp;</span><span style="line-height: 1.6em;">the first realization of such coherent dipolar interactions with polar molecules in a lattice, its full\&nbsp;</span><span style="line-height: 1.6em;">potential was limited by the low lattice filling fractions. Using our ability to exquisitely control the\&nbsp;</span><span style="line-height: 1.6em;">initial atomic gas mixture, we loaded a Mott insulator of Rb and a band insulator of K into the\&nbsp;</span><span style="line-height: 1.6em;">lattice. This quantum synthesis approach led to signicantly higher molecular filling fractions and\&nbsp;</span><span style="line-height: 1.6em;">represents the first fully connected system of polar molecules in an optical lattice. This low-entropy\&nbsp;</span><span style="line-height: 1.6em;">quantum gas of polar molecules opens the door to interesting quantum simulations, which should\&nbsp;</span><span style="line-height: 1.6em;">be attainable in the next generation of the experiment.</span></p>
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University of Colorado Boulder
Boulder, CO
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