Manipulating molecular ion qubits

Our new preprint on coupling molecular and atomic ion qubits can be found at arXiv:2008.09201 .This work is in collaboration with the Eric Hudson and Wes Campbell groups at UCLA and Michael Heaven at Emory University.  

In this article we discuss a novel laser-free method of using an atomic ion for state preparation and readout of a molecular ion qubit called dipole-phonon quantum logic (DPQL) originally proposed by Hudson and Campbell [Phys. Rev. Lett. 125, 120501 (2020)]. DPQL couples polar molecular ions’ internal states with normal modes of trapped ions via adiabatic sweeping trap secular frequencies. This article discusses the class of diatomic molecule that possess an internal structure suitable for DPQL, presents experiment progress with candidate CaO+, and simulates operation fidelity with attention to experimental reality, including the effects of ion heating and Zeeman shifts. A scheme to utilize the virtual-phonon-mediated dipole-dipole interaction to perform an iSWAP gate is also discussed. In summary, this paper detailed a path towards an experimental demonstration of the basic interactions in DPQL for atom-molecule and molecule-molecule systems.Starting with two Ca+ ions, we react one with oxygen to form CaO+