{"id":234,"date":"2017-05-09T17:39:18","date_gmt":"2017-05-09T17:39:18","guid":{"rendered":"https:\/\/live-pattersongroup-physics-ucsb-edu-v01.pantheonsite.io\/?page_id=234"},"modified":"2025-02-24T06:38:29","modified_gmt":"2025-02-24T06:38:29","slug":"ground-state-cooling-of-polyatomic-molecules","status":"publish","type":"page","link":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/ground-state-cooling-of-polyatomic-molecules\/","title":{"rendered":"Ground State Cooling of Polyatomic Molecules"},"content":{"rendered":"


\n<\/a>A major goal of our group is to cool and detect a polyatomic molecule in its absolute ground state for the first time. \u00a0Our proposal to do so, using a combination of established AMO methods and a few new tricks of our own, is described here<\/a>.<\/p>\n

The ability to prepare and readout the state of these molecules has the potential to unlock new frontiers in spectroscopy, precision measurement, and quantum information – and will let us start treating molecules like the perfect quantum system they are.<\/p>\n

Our plan to cool these molecules begins with co-trapping the molecular ion of choice with a laser coolable atomic ion, likely Sr+<\/sub>. The internal state of the molecule is cooled to ~10K via cryogenic buffer gas cooling, and the motional state in the trap is cooled to ultracold regime via sympathetic cooling of the co-trapped atom. \u00a0The\u00a0internal state and the motional state of the ion can then be coupled by applying spatially non-uniform fields; for example, microwave-frequency modulated optical standing waves can couple molecule rotation and molecule motion. \u00a0This method is closely related to Raman sideband cooling, a well established technique for laser cooling atoms. \u00a0State readout is achieved by reversing this process – selectively heating the trapped ensemble, conditional on the internal state of the molecule. \u00a0This readout could be described as a loose form of quantum logic spectroscopy – but works under far less exact conditions \u00a0than high fidelity QLS requires<\/p>\n

Why polyatomic molecules?<\/strong><\/h4>\n

The last 2 years have seen enormous progress \u00a0cooling\u00a0diatomic molecular ions, with a particular emphasis on light diatomics, such as CaH+<\/sub>. It is natural to think that cooling polyatomic molecules would be considerably harder than cooling diatomics – in atomic systems, added complexity typically brings added difficulty. \u00a0In fact, we believe the opposite is true: polyatomic molecules both provide access to significant new physics, and are in fact easier to control than diatomics.<\/p>\n

Polyatomic molecules have rich spectra of connected states.<\/h6>\n

Our plans to cool large molecular ions begins with buffer gas cooling them to ~ 10 Kelvin. Polyatomic molecules and diatomics look very different at this temperature. \u00a0Polyatomics exhibit a rich manifold of rotational states, all of which can be addressed via low frequency (< 20 GHz) synthesizers. \u00a0Although addressing these levels requires substantial complexity, this complexity lies just where we want it – inside a modern, high frequency arbitrary waveform generator. \u00a0In contrast, linear molecules exhibit sparse manifolds of states, and driving these transitions directly requires challenging THz electronics<\/p>\n

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Polyatomic molecules can be chiral<\/h6>\n

No molecule with 3 or fewer atoms – in fact no planar molecule – \u00a0can be chiral. \u00a0The ability to manipulate and detect the exact quantum state of a polyatomic molecular ion would be a major asset to the community looking for the predicted – but never observed – parity violating energy differences between otherwise equivalent right- and left- handed molecules. \u00a0The tools we are developing will also realize single molecule, non-destructive chiral analysis – and molecule by molecule chiral separation – tools that lie currently far beyond the state of the art<\/p>\n

Polyatomic molecules\u00a0couple well to existing microwave technology<\/h6>\n

Light hydrides, such as\u00a0CaH+<\/sub>, have rotational transitions in the 100s of GHz. \u00a0While our ability to produce well controlled radiation\u00a0in this challenging regime is improving rapidly, our agility in the 0-40 GHz regime is substantially greater; below 20 GHz, essentially arbitrary waveforms can now be reliably produced from off the shelf, direct digital synthesis based instruments.<\/p>\n

Polyatomic molecules are also well suited to existing quantum<\/em> microwave technology. \u00a0In particular, superconducting striplines, which typically operate in the 5 GHz range, could be efficiently coupled to the rotational states of trapped polyatomic molecular ions.<\/p>\n","protected":false},"excerpt":{"rendered":"

A major goal of our group is to cool and detect a polyatomic molecule in its absolute ground state for the first time. \u00a0Our proposal to do so, using a combination of established AMO methods and a few new tricks of our own, is described here. The ability to prepare and readout the state of […]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":1,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-234","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/wp-json\/wp\/v2\/pages\/234","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/wp-json\/wp\/v2\/comments?post=234"}],"version-history":[{"count":10,"href":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/wp-json\/wp\/v2\/pages\/234\/revisions"}],"predecessor-version":[{"id":1148,"href":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/wp-json\/wp\/v2\/pages\/234\/revisions\/1148"}],"wp:attachment":[{"href":"https:\/\/pattersongroup.physics.ucsb.edu\/index.php\/wp-json\/wp\/v2\/media?parent=234"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}