Quantum Logic Control of a Single Molecular Ion

Event Details
Event Date
Speaker Name/Affiliation
Dietrich Liebfried / NIST Boulder
Seminar Type/Subject
Event Details & Abstracts

An amazing level of quantum control is routinely reached in modern experiments with atoms, but similar control over molecules has been an elusive goal. We recently proposed a method based on quantum logic spectroscopy [1] to address this problem for a wide class of molecular ions [2]. We have now realized the basic elements of this proposal. In our demonstration, we trap a calcium ion together with a calcium hydride ion (CaH+) that is a convenient stand-in for more general molecular ions. We cool the two-ion crystal to its motional ground state and then drive motional "sidebands" of Raman transitions in the molecular ion, meaning that a transition in the molecule is accompanied by a single quantum of excitation in the motion of the ion pair. We can efficiently detect this single quantum with the calcium ion, which projects the molecule into the final state of the sideband transition, a known, pure quantum state. The molecule can be coherently manipulated after the projection, and its resulting state read out by another quantum logic state detection [3]. We demonstrate this by driving Rabi oscillations between rotational states. All transitions we address in the molecule are either driven by a single, far off-resonant continuous-wave laser or by a far-off-resonant frequency comb. This makes our approach applicable to control and precision measurement of a large class of molecular ions. [1] P.O. Schmidt, et al. Science 309, 749 (2005) [2] D. Leibfried, New J. Phys. 14, 023029 (2012) [3] C.-W. Chou, et al. Nature 545, 203 (2017)