Theoretical spectroscopy of trans-HNNH+ and isotopomers

The B11244 story: rovibrational calculations for C3H(+) and C3H(-) revisited

New theoretical values for the rovibrational parameters of C3H(+) and C3H(-) in the ground vibrational states are reported for the quartic internal coordinate force fields constructed by Huang et al. [Astrophys. J., Lett. 768, L25 (2013)] and Fortenberry et al. [Astrophys. J. 772, 39 (2014)]. Effective spectroscopic parameters are derived from the rovibrational energies, calculated up to J = 20 for C3H(+) and J = 12 for C3H(-) by means of a computational strategy for numerically exact rovibrational computations. Our results help to resolve a disharmony between the experimental observations and previous theoretical predictions in the case of C3H(+): we show that the previously used perturbational approach is not sufficient to reliably predict relevant spectroscopic properties of C3H(+) and that the force field of Huang et al. in combination with the numerically exact rovibrational treatment in fact supports the experimental identification of C3H(+), in contrast to the original conclusion of Huang et al. and Fortenberry et al. that the astronomical assignment of the B11244 carrier to C3H(+) is incorrect.

Quantum dynamics with sparse grids: a combination of Smolyak scheme and cubature. Application to methanol in full dimensionality

Quantum dynamical approaches based on product-grids are limited to the studies of molecular systems with few degrees of freedom, typically less than ten. Recently, Avila et al. [G. Avila, T. Carrington, J. Chem. Phys., 131 (2009) 174103] have introduced the Smolyak scheme [S.A. Smolyak, Sov. Math. Dokl., 4 (1963) 240], which considerably reduces the size of the grids. This approach has pushed back the present calculation limits on the vibrational spectra of polyatomic molecules. In the present study, we have developed an extension of the standard Smolyak scheme in which this scheme is combined with multidimensional grids, such as cubatures, to obtain new sparse grids. This scheme has been applied to the study of the torsional energy levels of methanol in full dimensionality (12D).

Controlled full adder-subtractor by vibrational computing

The implementation of a quantum-controlled full adder-subtractor of two binary digits and of a "carry in" or a "borrow in" is simulated by encoding four qubits in the vibrational eigenstates of a tetra-atomic molecule (trans-HONO). The laser field of the gate is computed using optimal control theory by treating dynamics in full dimensionality. A controlled qubit enforces the addition or the subtraction. The global unitary transformation that connects the inputs to the outputs is driven by a single laser pulse. This decreases the duration of the operation and allows for a better use of the optical resources and for an improvement of the fidelity (>97%). Initialization and reading out are discussed. The timescale of the sequence initialization, gate and read out is<100 ps.