Southwest Quantum Information and Technology

Controlling trapped-ion motional modes for precision measurement and CVQC

Presenting Author: David Allcock, University of Oregon
Contributing Author(s): Jeremy Metzner, Alexander Quinn, Sean Brudney, Isam Moore, Gabe Gregory, Colin Bruzewicz, John Chiaverini, David Wineland

Motional modes of trapped ions have been shown to be a useful tool for quantum sensing as well as a platform for performing continuous variable quantum computing (CVQC). Both applications require the ability to prepare well-defined motional states with high fidelity. Many of these states can be generated from motional ground states without the use of laser fields. We report our progress towards generation of one-mode and two-mode squeezed states using parametric excitation. These operations help to create motional state interferometers and can be used to achieve Heisenberg-limited phase sensitivities. We present a preliminary implementation of an SU(1,1) interferometer using two motional modes of a 40Ca+ ion in a Paul trap. To characterize motional states, the ions’ motion is coupled to internal ‘spin’ states, which are distinguishable through spin-dependent fluorescence. Photon scattering causes the ion to recoil, which generally decoheres the ions’ motional modes. This decoherence prevents mid-algorithm measurements, which are necessary for processes that require classical feedback. To address this issue, we describe progress towards the use of ‘protected’ modes (See also P.-Y. Hou et al., arXiv:2205.14841) within chains consisting of an odd number of ions, where the center ion has zero displacement. The protection offered by these ions is measured by analysis of the heating rates and coherence time of the protected mode during scattering events. Support from ARO and NSF.

(Session 12 : from 2:45 pm - 3:15 pm )