Experimental quantum information processing with 43Ca+ ions

TL;DR

This paper demonstrates advanced quantum information processing techniques with 43Ca+ ions, including ground state cooling, state initialization, and readout, highlighting its potential as a robust quantum memory with long coherence times.

Contribution

It presents the first implementation of QIP with 43Ca+ ions, overcoming its complex level structure to achieve high-fidelity operations and long coherence times.

Findings

Ground state cooling and efficient readout achieved

Quantum memory coherence time exceeds several seconds

Phase errors do not limit experiments up to 100 ms

Abstract

For quantum information processing (QIP) with trapped ions, the isotope 43Ca+ offers the combined advantages of a quantum memory with long coherence time, a high fidelity read out and the possibility of performing two qubit gates on a quadrupole transition with a narrow-band laser. Compared to other ions used for quantum computing, 43Ca+ has a relatively complicated level structure. In this paper we discuss how to meet the basic requirements for QIP and demonstrate ground state cooling, robust state initialization and efficient read out for the hyperfine qubit with a single 43Ca+ ion. A microwave field and a Raman light field are used to drive qubit transitions, and the coherence times for both fields are compared. Phase errors due to interferometric instabilities in the Raman field generation do not limit the experiments on a time scale of 100 ms. We find a quantum information storage time of many seconds for the hyperfine qubit.