Cold and ultracold molecules: science, technology and applications

In order to explore parity violating effects in chiral molecules, of interest in some models of evolution towards homochirality, quantum stochastic resonance (QSR) is studied for the population difference between the two enantiomers of a chiral molecule (hence for the optical activity of the sample), under low viscous friction and in the deep quantum regime. The molecule is described by a two-state model in an asymmetric double well potential where the asymmetry is given by the known predicted parity violating energy difference (PVED) between enantiomers. In the linear response to an external driving field that lowers and rises alternatively each one of the minima of the well, a signal of QSR is predicted only in the case that the PVED is different from zero, the resonance condition being independent on tunneling between the two enantiomers. It is shown that, at resonance, the fluctuations of the first order contribution to the internal energy are zero. Due to the small value of the PVED, the resonance would occur in the ultracold regime. Some proposals concerning the external driving field are suggested.

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“…However, recent works 35 show that it might be possible in the near future to cool polyatomic molecules to ultralow temperatures as well.…”

Section: Resultsmentioning

confidence: 99%

Quantum stochastic resonance in parity violating chiral molecules

Bargueño

Miret‐Artés

Gonzalo

2011

Phys. Chem. Chem. Phys.

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“…The cold molecules in these studies are generally diatomic but also include few-atom molecules such as ND 3 . 2,3 Extending this work to the cooling of larger molecules is of high interest, as reviewed by Meijer et al 4 and references therein. For example, chemical reaction rates at low temperatures are of great current interest, and extending these studies to important large molecules is essential.…”

Section: Introductionmentioning

confidence: 97%

Cooling and collisions of large gas phase molecules

Patterson

Tsikata

Doyle

2010

Phys. Chem. Chem. Phys.

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The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters. Cold and dense samples of naphthalene (C 10 H 8 ) are produced using buffer gas cooling in combination with rapid, high flow molecule injection. The observed naphthalene density is n E 10 11 cm À3 over a volume of a few cm 3 at a temperature of 6 K. We observe naphthalene-naphthalene collisions through two-body loss of naphthalene with a loss cross section of s N-N = 1.4 Â 10 À14 cm 2 . Analysis is presented that indicates that this combination of techniques will be applicable to many comparably sized molecules. This technique can also be combined with cryogenic beam methods 1 to produce cold, high flux, continuous molecular beams.

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“…slowing techniques have recently been developed for molecular ensembles 11 and photo-association experiments with atoms in magneto-optical traps have reached the rovibrational ground state 1 , the achievable molecular phase-space densities are still far from the point of quantum degeneracy. Here, we exploit the fact that high phase-space densities can readily be achieved for atoms and that atoms can efficiently be associated on Feshbach resonances to form molecules 7 with minimal loss of phase-space density when an optical lattice is present.…”

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confidence: 99%

An ultracold high-density sample of rovibronic ground-state molecules in an optical lattice

et al. 2010

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Control over all internal and external degrees of freedom of molecules at the level of single quantum states will enable a series of fundamental studies in physics and chemistry 1,2 . In particular, samples of ground-state molecules at ultralow temperatures and high number densities will facilitate new quantum-gas studies 3 and future applications in quantum information science 4 . However, high phase-space densities for molecular samples are not readily attainable because efficient cooling techniques such as laser cooling are lacking. Here we produce an ultracold and dense sample of molecules in a single hyperfine level of the rovibronic ground state with each molecule individually trapped in the motional ground state of an optical lattice well. Starting from a zero-temperature atomic Mott-insulator state 5 with optimized double-site occupancy 6 , weakly bound dimer molecules are efficiently associated on a Feshbach resonance 7 and subsequently transferred to the rovibronic ground state by a stimulated four-photon process with >50% efficiency. The molecules are trapped in the lattice and have a lifetime of 8 s. Our results present a crucial step towards Bose-Einstein condensation of groundstate molecules and, when suitably generalized to polar heteronuclear molecules, the realization of dipolar quantumgas phases in optical lattices [8][9][10] .Recent years have seen spectacular advances in the field of atomic quantum gases. Ultracold atomic samples have been loaded into optical lattice potentials, enabling the realization of strongly correlated many-body systems and the direct observation of quantum phase transitions with full control over the entire parameter space 5 . Molecules with their higher level of complexity are expected to have a crucial role in future-generation quantumgas studies. For example, the long-range dipole-dipole force between polar molecules gives rise to nearest-neighbour and next-nearest-neighbour interaction terms in the extended BoseHubbard Hamiltonian and should thus lead to unusual many-body states in optical lattices in the form of striped, checkerboard and supersolid phases [8][9][10] .An important prerequisite for all proposed molecular quantumgas experiments is the capability to fully control all internal and external quantum degrees of freedom of the molecules. For radiative and collisional stability, the molecules need to be prepared in their rovibronic ground state, that is, the lowest vibrational and rotational level of the lowest electronic state, and preferably in its energetically lowest hyperfine sublevel. As a starting point for the realization of new quantum phases, the molecular ensemble should be in the ground state of the many-body system. Such state control is possible only at ultralow temperatures and sufficiently high particle densities. Although versatile non-optical cooling and slowing techniques have recently been developed for molecular ensembles 11 and photo-association experiments with atoms in magneto-optical traps have reached the rovibrational ground sta...

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Cold and ultracold molecules: science, technology and applications

Cited by 1,385 publications

References 448 publications

Quantum stochastic resonance in parity violating chiral molecules

Quantum stochastic resonance in parity violating chiral molecules

Cooling and collisions of large gas phase molecules

An ultracold high-density sample of rovibronic ground-state molecules in an optical lattice

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