Abstract
Preparing molecules at rest and in a very pure quantum state is a long-standing aspiration in chemistry and physics, so far achieved only for a select set of molecules in dedicated experimental setups. Here, a quantum-limited combination of mass spectrometry and Raman spectroscopy is proposed that should be applicable to a wide range of molecular ions. Excitation of electrons in the molecule followed by uncontrolled decay and branching into several lower-energy states is avoided. Instead, the molecule is always confined to rotational states within the electronic and vibrational ground-state manifold, while a co-trapped atomic ion provides efficient entropy removal and allows for extraction of information about the molecule. The outlined techniques might enable the preparation, manipulation and measurement of a multitude of molecular ion species with the same instrument, with applications including, but not limited to, precise determination of molecular properties and fundamental tests of physics.
Highlights
Milliseconds, respectively, and the rotational state distribution will equilibrate to the blackbody temperature of the trap within a few seconds [5, 6]
For not too different masses, it should be possible to cool the normal modes of motion of both ions to the ground state, analogous to ground-state cooling demonstrated with different species of atomic ions [16, 23], which has been implemented for a range of masses 1/3 ma/ma 2
Manipulation of rotational states, ideally without altering the vibrational and the electronic state, might proceed by combining Raman transitions [24] driven by optical frequency combs [25] with a technique similar to what has been used for state preparation and readout in two-ion
Summary
Manipulation of rotational states, ideally without altering the vibrational and the electronic state, might proceed by combining Raman transitions [24] driven by optical frequency combs [25] with a technique similar to what has been used for state preparation and readout in two-ion. Quantum logic clocks [16] In this way, entropy can be removed from the molecular rotational degree of freedom by indirectly coupling it to the near-perfect reservoir of a light field. Entropy can be removed from the molecular rotational degree of freedom by indirectly coupling it to the near-perfect reservoir of a light field This can be accomplished via closed-cycle electronic transitions of the co-trapped atomic ion. The rotational states of the molecule are manipulated by inducing Raman transitions due to the light fields of two counter-propagating frequency combs (orange arrows) of equal repetition rate ωm/(2π ) and variable relative carrier-envelope phase ωo.
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