Abstract:The study of ultracold molecules tightly trapped in an optical lattice can expand the frontier of precision measurement and spectroscopy, and provide a deeper insight into molecular and fundamental physics. Here we create, probe, and image microkelvin 88 Sr 2 molecules in a lattice, and demonstrate precise measurements of molecular parameters as well as coherent control of molecular quantum states using optical fields. We discuss the sensitivity of the system to dimensional effects, a new bound-to-continuum sp… Show more
“…Note that if optical selection rules (rather than spin-statistics restrictions) allow only a single partial wave J in the continuum, then quantum mechanical and quasiclassical angular distributions strictly agree [13]. The dotted red line corresponds to the ab initio molecular potential [23], the solid green line to the potential that is optimized to reproduce long-range properties [24], and the dashed yellow line to the ab initio potential that was manually fitted for a better spectroscopic agreement with weakly bound states [25]. Photodissociation of these very weakly bound molecules does not yet reach the expected high-energy limit of β2 = 2 at the experimentally accessible continuum energies up to 260 mK (5.5 GHz).…”
Processes that break molecular bonds are typically observed with molecules occupying a mixture of quantum states and successfully described with quasiclassical models, while a few studies have explored the distinctly quantum mechanical low-energy regime. Here we use photodissociation of diatomic strontium molecules to demonstrate the crossover from the ultracold, quantum regime where the photofragment angular distributions strongly depend on the kinetic energy, to the energyindependent quasiclassical regime. Using time-of-flight velocity map imaging for photodissociation channels with millikelvin reaction barriers, we explore photofragment energies in the 0.1-300 mK range experimentally and up to 3 K theoretically, and discuss the energy scale at which the crossover occurs. Furthermore, we find that the effects of quantum statistics can unexpectedly persist to high photodissociation energies.
“…Note that if optical selection rules (rather than spin-statistics restrictions) allow only a single partial wave J in the continuum, then quantum mechanical and quasiclassical angular distributions strictly agree [13]. The dotted red line corresponds to the ab initio molecular potential [23], the solid green line to the potential that is optimized to reproduce long-range properties [24], and the dashed yellow line to the ab initio potential that was manually fitted for a better spectroscopic agreement with weakly bound states [25]. Photodissociation of these very weakly bound molecules does not yet reach the expected high-energy limit of β2 = 2 at the experimentally accessible continuum energies up to 260 mK (5.5 GHz).…”
Processes that break molecular bonds are typically observed with molecules occupying a mixture of quantum states and successfully described with quasiclassical models, while a few studies have explored the distinctly quantum mechanical low-energy regime. Here we use photodissociation of diatomic strontium molecules to demonstrate the crossover from the ultracold, quantum regime where the photofragment angular distributions strongly depend on the kinetic energy, to the energyindependent quasiclassical regime. Using time-of-flight velocity map imaging for photodissociation channels with millikelvin reaction barriers, we explore photofragment energies in the 0.1-300 mK range experimentally and up to 3 K theoretically, and discuss the energy scale at which the crossover occurs. Furthermore, we find that the effects of quantum statistics can unexpectedly persist to high photodissociation energies.
“…Near-threshold vibrational splittings depend chiefly on the dominant long range R −6 van der Waals interaction and are to a large extent insensitive to the details of the short range potential 20,21 . The narrow intercombination lines present in divalent species facilitate measurements of the positions of near-threshold bound states of Yb 2 22 and Sr 2 23,24 to an already impressive sub-kHz accuracy which in the future could further be improved by several orders of magnitude using lattice clock techniques 25 . Thus, weakly bound molecules composed of Yb or Sr atoms make excellent testing grounds in the search for new interactions by uniting precision measurements with a relatively simple level structure.Figure 1New gravitylike forces and long-range atomic interactions.…”
Several extensions to the Standard Model of particle physics, including light dark matter candidates and unification theories predict deviations from Newton’s law of gravitation. For macroscopic distances, the inverse-square law of gravitation is well confirmed by astrophysical observations and laboratory experiments. At micrometer and shorter length scales, however, even the state-of-the-art constraints on deviations from gravitational interaction, whether provided by neutron scattering or precise measurements of forces between macroscopic bodies, are currently many orders of magnitude larger than gravity itself. Here we show that precision spectroscopy of weakly bound molecules can be used to constrain non-Newtonian interactions between atoms. A proof-of-principle demonstration using recent data from photoassociation spectroscopy of weakly bound Yb2 molecules yields constraints on these new interactions that are already close to state-of-the-art neutron scattering experiments. At the same time, with the development of the recently proposed optical molecular clocks, the neutron scattering constraints could be surpassed by at least two orders of magnitude.
“…This is, to our knowledge, the most accurate determination to date of the dissociation energy of a molecule. The ability to measure molecular transitions with a high precision is highly relevant to proposed searches for variations in fundamental constants [8][9][10][19][20][21][22][23][24].…”
Section: Discussionmentioning
confidence: 99%
“…Previous studies have focused on microwave transitions [20,21] and high-lying vibrational states [22][23][24]. * s.l.cornish@durham.ac.uk…”
Reprinted with permission from the American Physical Society: Molony, P.K. and Kumar, A. and Gregory, P.D. and Kliese, R. and Puppe, T. and Le Sueur, C.R. and Aldegunde, J. and Hutson, J.M. and Cornish, S.L. (2016) 'Measurement of the binding energy of ultracold 87Rb133Cs molecules using an oset-free optical frequency comb.', Physical review A., 94 (2). 022507 c 2016 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information:
Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We report the binding energy of 87 Rb 133 Cs molecules in their rovibrational ground state measured using an offset-free optical frequency comb based on difference frequency generation technology. We create molecules in the absolute ground state using stimulated Raman adiabatic passage (STIRAP) with a transfer efficiency of 88%. By measuring the absolute frequencies of our STIRAP lasers, we find the energy-level difference from an initial weakly bound Feshbach state to the rovibrational ground state with a resolution of ∼5 kHz over an energy-level difference of more than 114 THz; this lets us discern the hyperfine splitting of the ground state. Combined with theoretical models of the Feshbach-state binding energies and ground-state hyperfine structure, we determine a zero-field binding energy of h×114 268 135.24(4)(3) MHz. To our knowledge, this is the most accurate determination to date of the dissociation energy of a molecule.
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