{"id":161,"date":"2021-02-03T11:05:04","date_gmt":"2021-02-03T11:05:04","guid":{"rendered":"https:\/\/qo.lab.uq.edu.au\/?page_id=161"},"modified":"2025-05-16T19:19:42","modified_gmt":"2025-05-16T09:19:42","slug":"superfluid-optomechanics","status":"publish","type":"page","link":"https:\/\/qo.lab.uq.edu.au\/?page_id=161","title":{"rendered":"Superfluid optomechanics"},"content":{"rendered":"\n<p class=\"has-drop-cap\">Superfluidity is a quantum state of matter that exists macroscopically in helium at low temperatures. The elementary excitations in superfluid helium have been probed with great success using techniques such as neutron and light scattering. However, measurements of phonon excitations have so far been limited to average thermodynamic properties or the driven response far out of thermal equilibrium. Here, we use cavity optomechanics to probe excitations in superfluid helium, such as vortex dynamics and nonlinear hydrodynamics, in real time.<\/p>\n\n\n\n<div style=\"height:50px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"859\" src=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/superfluid-optomechanics-1024x859.png\" alt=\"\" class=\"wp-image-1077\" style=\"width:696px;height:auto\" srcset=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/superfluid-optomechanics-1024x859.png 1024w, https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/superfluid-optomechanics-300x252.png 300w, https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/superfluid-optomechanics-768x644.png 768w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Artistic rendering of the whispering gallery modes on a silica microdisk covered in a thin film of superfluid helium. <\/figcaption><\/figure>\n<\/div>\n\n\n<div style=\"height:100px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Recent Work<\/h2>\n\n\n<div class=\"wp-block-ub-divider ub_divider ub-divider-orientation-horizontal\" id=\"ub_divider_931049f5-18a5-44c5-9918-992da916ba83\"><div class=\"ub_divider_wrapper\" style=\"position: relative; margin-bottom: 2px; width: 100%; height: 2px; \" data-divider-alignment=\"center\"><div class=\"ub_divider_line\" style=\"border-top: 2px solid #ccc; margin-top: 2px; \"><\/div><\/div><\/div>\n\n\n<h2 class=\"wp-block-heading has-text-align-left has-large-font-size\" id=\"coherent_vortex_dynamics\">Nonlinear wave dynamics on a chip<\/h2>\n\n\n\n<figure class=\"wp-block-video\"><video height=\"480\" style=\"aspect-ratio: 1218 \/ 480;\" width=\"1218\" controls src=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/driven-wavetank-1_mp4_dvd.mp4\"><\/video><\/figure>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"2420\" height=\"1840\" src=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/waveflume-2.png\" alt=\"\" class=\"wp-image-1155\" style=\"width:679px;height:auto\" srcset=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/waveflume-2.png 2420w, https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/waveflume-2-300x228.png 300w\" sizes=\"auto, (max-width: 2420px) 100vw, 2420px\" \/><\/figure>\n<\/div>\n\n\n<p>There are striking similarities between shallow water waves and nonlinear wave dynamics in superfluid helium. Using a nanoscale wave flume coated in superfluid, we use the optomechanical interaction between light and superfluid helium films to observe extreme nonlinear hydrodynamics. This work paves the way for the exploration and discovery of nonlinear behaviours unattainable in classical wave flumes. <\/p>\n\n\n\n<p><span style=\"text-decoration:underline;\">Read more:<\/span><\/p>\n\n\n\n<p>M. Reeves, <em>et al.,<\/em> <a href=\"https:\/\/doi.org\/10.48550\/arXiv.2504.13001\">Nonlinear wave dynamics on a chip<\/a>, <em>arXiv<\/em>:2504.13001, (2025).<\/p>\n\n\n<div class=\"wp-block-ub-divider ub_divider ub-divider-orientation-horizontal\" id=\"ub_divider_8ac41282-f98b-415a-a0a5-9aa580e4c464\"><div class=\"ub_divider_wrapper\" style=\"position: relative; margin-bottom: 2px; width: 100%; height: 2px; \" data-divider-alignment=\"center\"><div class=\"ub_divider_line\" style=\"border-top: 2px solid #ccc; margin-top: 2px; \"><\/div><\/div><\/div>\n\n\n<h2 class=\"wp-block-heading has-text-align-left has-large-font-size\" id=\"coherent_vortex_dynamics\">Engineered entropic forces allow ultrastrong dynamical backaction<\/h2>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"597\" height=\"437\" src=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/sciadv_sf.png\" alt=\"\" class=\"wp-image-1082\" style=\"width:717px;height:auto\" srcset=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/sciadv_sf.png 597w, https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/sciadv_sf-300x220.png 300w\" sizes=\"auto, (max-width: 597px) 100vw, 597px\" \/><figcaption class=\"wp-element-caption\">Artistic rendition of a silica microsphere covered in a thin film of superfluid, which experiences dynamical backaction due to the optomechanical coupling between an applied optical field and the superfluid. <\/figcaption><\/figure>\n<\/div>\n\n\n<p>By leveraging the optomechanical interaction between light and superfluid third sound on a silica microsphere, we demonstrate optomechanical phonon lasing with a threshold power of only a few picowatts. This platform allows us to engineer the dynamical backaction from entropic forces, which we have shown to exceed radiation pressure forces by eight orders of magnitude. These results pave the way for the study of nonlinear phenomena in fluids, which we explore in future work (see above). <\/p>\n\n\n\n<p><span style=\"text-decoration:underline;\">Read more:<\/span><\/p>\n\n\n\n<p>A. Sawadsky, <em>et al., <\/em><a href=\"https:\/\/www.science.org\/doi\/10.1126\/sciadv.ade3591\">Engineered entropic forces allow ultrastrong dynamical backaction<\/a>, <em>Science<\/em> <em>Advances<\/em>, <strong>9,<\/strong> 21, (2023).<\/p>\n\n\n\n<p><a href=\"https:\/\/www.science.org\/doi\/10.1126\/sciadv.ade3591\">Supplementary Material<\/a><\/p>\n\n\n<div class=\"wp-block-ub-divider ub_divider ub-divider-orientation-horizontal\" id=\"ub_divider_d76490a5-6451-4413-8ff6-10076b4f2926\"><div class=\"ub_divider_wrapper\" style=\"position: relative; margin-bottom: 2px; width: 100%; height: 2px; \" data-divider-alignment=\"center\"><div class=\"ub_divider_line\" style=\"border-top: 2px solid #ccc; margin-top: 2px; \"><\/div><\/div><\/div>\n\n\n<h2 class=\"wp-block-heading has-text-align-left has-large-font-size\" id=\"coherent_vortex_dynamics\">Coherent vortex dynamics in superfluid helium thin films<\/h2>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"597\" height=\"437\" src=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/science_sf.png\" alt=\"\" class=\"wp-image-1080\" style=\"width:621px;height:auto\" srcset=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/science_sf.png 597w, https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/science_sf-300x220.png 300w\" sizes=\"auto, (max-width: 597px) 100vw, 597px\" \/><figcaption class=\"wp-element-caption\">Sketch of the laser initialization of vortex clusters using the superfluid fountain pressure effect. <\/figcaption><\/figure>\n<\/div>\n\n\n<p>Quantized vortices are central to the behavior of two-dimensional superfluids, as recognized by the 2016 Nobel Prize in Physics. They had however not been directly observed in superfluid helium films, due to Angstr\u00f6m-sized cores and low refractive indices, which prevent direct optical imaging. In this work, we generated and detected quantized vortices to observe their dynamics through an alternate mechanism through their interaction with sound<strong> <\/strong>waves confined on the surface of an optical microresonator.<br><\/p>\n\n\n\n<p><span style=\"text-decoration:underline;\">Read more:<\/span><\/p>\n\n\n\n<p>Y. Sachkou, <em>et al., <\/em><a href=\"https:\/\/doi.org\/10.1126\/science.aaw9229\">Coherent Vortex Dynamics in a Strongly-Interacting Superfluid on a Silicon Chip<\/a>, <em>Science<\/em>, vol. <strong>366,<\/strong> no. 6472, pp. 1480-1485, (2019).<\/p>\n\n\n\n<p>See also: S. Forstner, <em>et al.,<\/em> <a href=\"https:\/\/iopscience.iop.org\/article\/10.1088\/1367-2630\/ab1bb5\">Modelling of vorticity, sound and their interaction in two-dimensional superfluids<\/a>, <br><i>New Journal of Physics<\/i>, vol. <strong>21<\/strong>, p. 053029, (2019).<br><\/p>\n\n\n\n<div style=\"height:250px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group alignwide is-nowrap is-layout-flex wp-container-core-group-is-layout-6c531013 wp-block-group-is-layout-flex\">\n<div class=\"wp-block-group is-nowrap is-layout-flex wp-container-core-group-is-layout-6c531013 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"352\" height=\"93\" src=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/qqol.png\" alt=\"\" class=\"wp-image-1058\" srcset=\"https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/qqol.png 352w, https:\/\/qo.lab.uq.edu.au\/wp-content\/uploads\/2025\/04\/qqol-300x79.png 300w\" sizes=\"auto, (max-width: 352px) 100vw, 352px\" \/><\/figure>\n\n\n<div class=\"wp-block-ub-divider ub_divider ub-divider-orientation-vertical\" id=\"ub_divider_38078fff-744f-434a-9f19-6da19aaa0fa4\"><div class=\"ub_divider_wrapper\" style=\"position: relative; width: 2px; height: 100px; \" data-divider-alignment=\"center\"><div class=\"ub_divider_line\" style=\"border-left: 2px solid #ccc; width: fit-content; height: 100px; \"><\/div><\/div><\/div>\n\n\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<p>Copyright \u00a9 2025 University of Queensland <\/p>\n\n\n\n<p><a href=\"https:\/\/www.uq.edu.au\/legal\/copyright-privacy-disclaimer\/\">UQ Privacy Policy<\/a><\/p>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Superfluidity is a quantum state of matter that exists macroscopically in helium at low temperatures. The elementary excitations in superfluid helium have been probed with great success using techniques such as neutron and light scattering. However, measurements of phonon excitations have so far been limited to average thermodynamic properties or the driven response far out [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"cybocfi_hide_featured_image":"","footnotes":""},"class_list":["post-161","page","type-page","status-publish","hentry"],"featured_image_src":null,"_links":{"self":[{"href":"https:\/\/qo.lab.uq.edu.au\/index.php?rest_route=\/wp\/v2\/pages\/161","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/qo.lab.uq.edu.au\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/qo.lab.uq.edu.au\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/qo.lab.uq.edu.au\/index.php?rest_route=\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/qo.lab.uq.edu.au\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=161"}],"version-history":[{"count":24,"href":"https:\/\/qo.lab.uq.edu.au\/index.php?rest_route=\/wp\/v2\/pages\/161\/revisions"}],"predecessor-version":[{"id":1681,"href":"https:\/\/qo.lab.uq.edu.au\/index.php?rest_route=\/wp\/v2\/pages\/161\/revisions\/1681"}],"wp:attachment":[{"href":"https:\/\/qo.lab.uq.edu.au\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=161"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}