{"id":3812,"date":"2015-02-10T00:00:00","date_gmt":"2015-02-10T00:00:00","guid":{"rendered":"https:\/\/wpdev.hmc.edu\/physics\/2015\/02\/10\/dispersion-engineering-with-cold-atoms-ferromagnetism-rotons-and-beyond\/"},"modified":"2015-02-10T00:00:00","modified_gmt":"2015-02-10T00:00:00","slug":"dispersion-engineering-with-cold-atoms-ferromagnetism-rotons-and-beyond","status":"publish","type":"physics_colloquium","link":"https:\/\/www.hmc.edu\/physics\/research\/colloquium\/dispersion-engineering-with-cold-atoms-ferromagnetism-rotons-and-beyond\/","title":{"rendered":"Dispersion Engineering with Cold Atoms: Ferromagnetism, Rotons, and Beyond"},"content":{"rendered":"<figure id=\"page-featured-image\" class=\"wp-block-image is-style-alignleft\" data-pic=\"pic-565.png\"><img decoding=\"async\" src=\"https:\/\/www.hmc.edu\/physics\/wp-content\/uploads\/sites\/22\/2023\/01\/pic-565.png\" alt=\"Promotional image for talk: Elements of a successful scientific talk\" data-pic=\"pic-565.png\" \/><\/figure>\n<p><strong>Speaker(s):<\/strong> Colin V. Parker (\u201906)<\/p>\n<p>For classical or quantum Hamiltonians, one typically writes the kinetic energy, or dispersion, as a simple parabola for small momentum. However, particles traveling in certain periodic potentials (i.e. lattices) may have a dispersion that is minimized at multiple values of momentum or that depends upon the fourth power of momentum, preventing such a simple description. My collaborators and I have realized these \u201cengineered dispersions\u201d experimentally by shaking cold cesium atoms back and forth in optical standing waves. Despite the fact that our atoms experience only short-range interactions, we observe behavior typically seen in strongly interacting condensed matter systems. For example, the atoms form domains like a ferromagnet (see image) despite having fixed spin. We also observe a set of excitations called rotons, first observed in superfluid helium, in which the phase and group velocity point in opposite directions. These experiments demonstrate the important role played by lattice-generated dispersion in many-body systems.<\/p>\n","protected":false},"author":1,"featured_media":0,"template":"","class_list":["post-3812","physics_colloquium","type-physics_colloquium","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.hmc.edu\/physics\/wp-json\/wp\/v2\/physics_colloquium\/3812","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hmc.edu\/physics\/wp-json\/wp\/v2\/physics_colloquium"}],"about":[{"href":"https:\/\/www.hmc.edu\/physics\/wp-json\/wp\/v2\/types\/physics_colloquium"}],"author":[{"embeddable":true,"href":"https:\/\/www.hmc.edu\/physics\/wp-json\/wp\/v2\/users\/1"}],"wp:attachment":[{"href":"https:\/\/www.hmc.edu\/physics\/wp-json\/wp\/v2\/media?parent=3812"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}