Measurement of line widths and permanent electric dipole moment change of the Ce 4f-5d transition in Y_2SiO_5 for a qubit readout scheme in rare-earth ion based quantum computing

TL;DR

This study measures the line widths and electric dipole moment change of Ce ions in Y_2SiO_5 to evaluate their potential as sensors for qubit state readout in rare-earth ion quantum computing.

Contribution

It provides the first detailed measurements of the homogeneous line width and dipole moment change of Ce ions, demonstrating their suitability for quantum sensing applications.

Findings

Homogeneous line width of about 3 MHz limited by excited state lifetime

Calculated oscillator strength, absorption cross section, and saturation intensity

Dipole moment change of 6.3 x 10^-30 C·m, much larger than Pr ions

Abstract

In this work the inhomogeneous (zero-phonon line) and homogeneous line widths, and one projection of the permanent electric dipole moment change for the Ce 4f-5d transition in Y_2SiO_5 were measured in order to investigate the possibility for using Ce as a sensor to detect the hyperfine state of a spatially close-lying Pr or Eu ion. The experiments were carried out on Ce doped or Ce-Pr co-doped single Y_2SiO_5 crystals. The homogeneous line width was measured to be about 3 MHz, which is essentially limited by the excited state lifetime. Based on the line width measurements, the oscillator strength, absorption cross section and saturation intensity were calculated to be about 9*10^-7, 5*10^-19 m^2 and 1*10^7 W/m^2, respectively. One projection of the difference in permanent dipole moment, Delt_miu_Ce, between the ground and excited states of the Ce ion was measured as 6.3 * 10^-30 C*m, which is about 26 times as large as that of Pr ions. The measurements done on Ce ions indicate that the Ce ion is a promising candidate to be used as a probe to read out a single qubit ion state for the quantum computing using rare-earth ions.