Prospects for ultracold carbon via charge exchange reactions and laser cooled carbides

Wells, Nathan; Lane, Ian C.

doi:10.1039/c1cp21304k

Cited by 32 publications

(30 citation statements)

References 107 publications

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“…Until recently, the laser cooling of molecules to ultracold temperatures was verified from the perspective of experiment [9][10][11]. Transverse laser cooling was applied to beams of SrF [9] and YO [10] molecules, and longitudinal laser cooling was applied to a supersonic beam of CaF molecules [11], From a theoretical point of view, a series of diatomic polar molecules were considered to be potential molecules for laser cooling, such as the alkaline-earth-metal monofluorides (e.g., BeF [12] and RaF [13]), the alkalineearth-metal monohydrides [14] (e.g., BeH, MgH, CaH, SrH, and BaH) and other polar molecules (e.g., CH [15] and A1F [16], etc.). According to previous research work [8], the molecule must meet the following criteria to be a promising laser-cooling candidate.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of laser cooling of magnesium monofluoride usingab initiomethods

et al. 2015

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A theoretical investigation of the feasibility of laser-cooling the 24M g19F molecule is performed using ab initio calculations. The low-lying electronic states are determined by the multireference configuration-interaction (MRCI) method, where the Davidson modification ( + 0 with the Douglas-Kroll-Hess scalar relativistic correction is also taken into account. The calculated spectroscopic constants are in excellent agreement with the available experimental data. The Franck-Condon factors (FCFs), radiative lifetimes, and radiative widths are verified by calculating the potential energy curves and the transition dipole moment of the A 2n (v') -*• X 2S +(v) transition. Our calculation indicates that the A 2Tl(u' = 0) -> X 2S + (v = 0) transition provides highly diagonally distributed FCFs (/oo = 0.917) and a short radiative lifetime (r = 7.96 ns) for the A 2n(v' = 0) state, which is short enough for rapid laser cooling. The required cooling wavelengths are in the ultraviolet region. A comprehensive scheme demonstrates the possibility of laser-cooling MgF. Moreover, the C 2S + state is confirmed to be a Rydberg state at the MRCI level, which is in line with experimental conjecture.The B 2 n and D 2 £ + states are also reported, but they have not been observed to date.

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Section: Introductionmentioning

confidence: 99%

Theoretical study of laser cooling of magnesium monofluoride usingab initiomethods

et al. 2015

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“…The A 2 →X 2 transition of CH was pointed out to be dominated by diagonal bands, making it a potential cooling candidate (Wells and Lane, 2011b). SiH is considered to be suitable for laser cooling by Zhang et al (2018), although they ignored the SOC effects in their laser cooling schemes.…”

Section: Introductionmentioning

confidence: 99%

A Theoretical Study on Laser Cooling Feasibility of Group IVA Hydrides XH (X = Si, Ge, Sn, and Pb): The Role of Electronic State Crossing

et al. 2020

Front. Chem.

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The feasibility of direct laser cooling of SiH, GeH, SnH, and PbH is investigated and assessed based upon first principles. The internally contracted multi-reference configuration interaction method with the Davidson correction is applied. Very good agreement is obtained between our computed spectroscopic constants and the available experimental data. We find that the locations of crossing point between the B 2 − and A 2 states have the tendency of moving downwards from CH to SnH relative to the bottom of the corresponding A 2 potential, which precludes the laser cooling of GeH, SnH, and PbH. By including the spin-orbit coupling effects and on the basis of the A 2 5/2 →X 2 3/2 transition, we propose a feasible laser cooling scheme for SiH using three lasers with wavelengths varying from 400 to 500 nm, which features a very large vibrational branching ratio (0.9954) and a very short radiative lifetime (575 ns). Moreover, similar studies are extended to carbon monosulfide (CS) with a feasible laser cooling scheme proposed. The importance of electronic state crossing in molecular laser cooling is underscored, and our work suggests useful caveats to the choice of promising candidates for producing ultracold molecules.

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“…Furthermore, Fig. 2c hints at the intriguing possibility of using long-lived states for ultracold molecule photodissociation [29]. The shown transition from the least-bound subradiant excited state to the ground-state continuum should have an ultimate width limited by the subradiant state lifetime, corresponding to excess fragment energies of only a nanokelvin.…”

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confidence: 99%

Precise study of asymptotic physics with subradiant ultracold molecules

et al. 2014

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Weakly bound molecules have physical properties without atomic analogues, even as the bond length approaches dissociation. In particular, the internal symmetries of homonuclear diatomic molecules result in formation of two-body superradiant and subradiant excited states. While superradiance [1][2][3] has been demonstrated in a variety of systems, subradiance [4][5][6] is more elusive due to the inherently weak interaction with the environment. Here we characterize the properties of deeply subradiant molecular states with intrinsic quality factors exceeding 10 13 via precise optical spectroscopy with the longest molecule-light coherent interaction times to date. We find that two competing effects limit the lifetimes of the subradiant molecules, with different asymptotic behaviors. The first is radiative decay via weak magnetic-dipole and electric-quadrupole interactions. We prove that its rate increases quadratically with the bond length, confirming quantum mechanical predictions. The second is nonradiative decay through weak gyroscopic predissociation, with a rate proportional to the vibrational mode spacing and sensitive to short-range physics. This work bridges the gap between atomic and molecular metrology based on lattice-clock techniques [7], yielding new understanding of long-range interatomic interactions and placing ultracold molecules at the forefront of precision measurements.Simple molecules provide a wealth of opportunities for precision measurements. Their richer internal structure compared to atoms enables experiments that push the boundaries in determinations of the electric dipole moment of the electron [8], the electron-to-proton mass ratio and its variations [9,10], and parity violation [11]. Diatomic molecules are moving to the forefront of manybody science [12] and quantum chemistry [13], providing glimpses into fundamental laws [14]. However, this attractive complexity of molecular structure has historically posed difficulties for manipulation and modeling [15]. This work removes many of these barriers by employing techniques of optical lattice atomic clocks [16,17] to control the quantum states of weakly bound homonuclear diatomic strontium molecules, in particular by using state-insensitive optical lattices [18] for molecular transitions with three types of optical transition moments. We observe strongly forbidden optical transitions in this asymptotic diatomic system, an ideal regime for studying the breakdown of the ubiquitous dipole approximation where the size of the quantum particle is a significant fraction of the resonant wavelength. We explain these observations with a state-of-the-art ab initio molecular model [19] and asymptotic scaling laws. The results prove that the quantum mechanical effect of subradiance can be exploited for precision spectroscopy, and demonstrate the promise of combining precise state control, coherent manipulation, and accurate ab initio calculations with recently available ultracold molecular systems.We create Sr 2 molecules by photoassociation [20] from ...

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Prospects for ultracold carbon via charge exchange reactions and laser cooled carbides

Cited by 32 publications

References 107 publications

Theoretical study of laser cooling of magnesium monofluoride usingab initiomethods

Theoretical study of laser cooling of magnesium monofluoride usingab initiomethods

A Theoretical Study on Laser Cooling Feasibility of Group IVA Hydrides XH (X = Si, Ge, Sn, and Pb): The Role of Electronic State Crossing

Precise study of asymptotic physics with subradiant ultracold molecules

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