Abstract
To control molecular scattering, we consider hydrogen molecules prepared in a coherent superposition of m states within a single rovibrational (v, j) energy eigenstate using Stark-induced adiabatic Raman passage (SARP). Specifically, SARP can prepare a bi-axial state of the HD molecule in which the HD bond axis exists simultaneously in two possible alignments at right angles to one another with a well-defined relative phase. We show that scattering from this biaxial state will interfere, resulting in a φ -dependent scattering intensity distribution, where φ is the azimuthal angle about the collision velocity direction. Using the scattering matrix extracted from our experiments on the rotationally inelastic collisions of quantum state prepared HD at low temperatures, we calculate the differential scattering cross-section dσ/dΩ, which shows an interference pattern as function of θ and φ in the image plane perpendicular to the collision velocity. The calculated scattering image shows that scattering from the bi-axial state directs molecules along well-defined angles, corresponding to interference maxima. Thus, the bi-axial state behaves like a double slit for molecular scattering. Moreover, by rotating the polarizations of the SARP preparation lasers, we can control the interference thereby altering the scattering angular distribution. This molecular interferometer, which experimentally measures the relative phases of the scattering matrix elements, allows a direct test of theoretical calculations on important, fundamental collision processes.
Highlights
Interference is a fundamental characteristic of the physical world that results from the intrinsic uncertainty in which multiple definite pathways connect the initial and final states of a system [1]
We have shown that a coherent superposition of degenerate m states within a single rovibrational eigenstate behaves like a multi-slit interferometer for molecular scattering
We considered the j = 2 rotationally inelastic scattering of HD prepared in coherent superpositions of m states within a single (v = 1, j = 2) eigenstate using Starkinduced adiabatic Raman passage (SARP)
Summary
Interference is a fundamental characteristic of the physical world that results from the intrinsic uncertainty in which multiple definite pathways connect the initial and final states of a system [1]. Using advanced techniques to prepare the quantum states of isolated atomic and molecular systems, recent experiments have illustrated the effects of these interferences on the integral or differential cross section of the scattering process. This is achieved by preparing the atom-molecule collision system in a phase coherent superposition of quantum states.
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