Mode shaping in mixed ion crystals of 40Ca2+ and 40Ca+

TL;DR

This study explores the structural configurations and vibrational modes of mixed 40Ca+ and 40Ca2+ Coulomb crystals in a linear Paul trap, advancing the understanding of mode shaping and spin-dependent configuration control.

Contribution

It provides experimental and theoretical insights into the behavior of mixed ion crystals, specifically focusing on mode shaping and structural transitions relevant to quantum information processing.

Findings

Successful production of 40Ca2+ ions via photoionisation.

Experimental and theoretical analysis of crystal configurations and vibrational modes.

Progress towards realizing mode shaping and spin-dependent structural changes in ion crystals.

Abstract

We present studies of mixed Coulomb crystals of 40Ca+ and 40Ca2+ ions in a linear Paul trap. Doubly charged ions are produced by photoionisation of trapped 40Ca+ with a vacuum ultraviolet laser source and sympathetically cooled via Doppler cooled 40Ca+ ions. We investigate experimentally and theoretically the structural configurations and the vibrational modes of these mixed crystals. Our results with 40Ca2+ are an important step towards experimental realization of the proposals for mode shaping in a linear crystal and spin-dependent configuration changes from zigzag to linear as proposed by Li et al., Phys. Rev. A 87, (2013) 052304 and Phys. Rev. Lett 108, (2012) 023003 using ions excited to Rydberg states.