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Spectroscopy and Coherence of an Excited-State Transition in $\text{Tm}^{3+}$:$\text{YAlO}_{3}$ at Telecommunication Wavelength

Luozhen Li, Akshay Babu Karyath, Mohsen Falamarzi Askarani, Maria Gieysztor, Hridya Meppully Sasidharan, Joshua A. Slater, Aaron D. Marsh, Philip J. T. Woodburn, Charles W. Thiel, Rufus L. Cone, Sara Marzban, Nir Alfasi, Patrick Remy, Wolfgang Tittel

Abstract

We characterize the spectroscopic and coherence properties of the 1451.37 nm excited-state zero-phonon line (ZPL) between the $^{3}F_{4}$ and the $^{3}H_{4}$ manifolds of a thulium-doped yttrium aluminum perovskite ($\text{Tm}^{3+}$:$\text{YAlO}_{3}$) crystal at temperatures around 1.5 K. We measure the absorption spectrum between the $^{3}H_{6}$ - $^{3}F_{4}$ and $^{3}F_{4}$ - $^{3}H_{4}$ manifolds, the inhomogeneous broadening of the $^{3}F_{4}$ - $^{3}H_{4}$ (excited-state) ZPL, and the lifetimes of the higher-lying and lower-lying excited states. We also investigate spectral hole-burning spectra with varying magnetic fields, which provides insight into hyperfine and superhyperfine interactions. Using again spectral holes but also optical free induction decays (FIDs), we assess optical coherence times, finding a maximum of 1.1 $μs$ when a 2T magnetic field is applied. Our results -- the first to demonstrate coherence of an excited-state transition in a rare-earth crystal -- suggest the possibility of exploiting such transitions for quantum technology.

Spectroscopy and Coherence of an Excited-State Transition in $\text{Tm}^{3+}$:$\text{YAlO}_{3}$ at Telecommunication Wavelength

Abstract

We characterize the spectroscopic and coherence properties of the 1451.37 nm excited-state zero-phonon line (ZPL) between the and the manifolds of a thulium-doped yttrium aluminum perovskite (:) crystal at temperatures around 1.5 K. We measure the absorption spectrum between the - and - manifolds, the inhomogeneous broadening of the - (excited-state) ZPL, and the lifetimes of the higher-lying and lower-lying excited states. We also investigate spectral hole-burning spectra with varying magnetic fields, which provides insight into hyperfine and superhyperfine interactions. Using again spectral holes but also optical free induction decays (FIDs), we assess optical coherence times, finding a maximum of 1.1 when a 2T magnetic field is applied. Our results -- the first to demonstrate coherence of an excited-state transition in a rare-earth crystal -- suggest the possibility of exploiting such transitions for quantum technology.

Paper Structure

This paper contains 1 section, 2 equations, 3 figures.

Table of Contents

  1. Acknowledgements

Figures (3)

  • Figure 1: (a) Energy levels of relevant transitions of Tm3+ in YAlO$_3$. (b) Transmission spectrum measured using a broadband LED, demonstrating absorption on Z1 to 3F4 transitions. (c) Photoluminescence (PL) rate at $\sim 800 \mathrm{nm}$ as a function of wavelength of a laser exciting the Y1 to 3H4 transitions. The inset shows a zoom-in of the Y1 to X1 ZPL. The crystal field levels of the upper states are identified in panels b) and c).
  • Figure 2: Spectral hole burning spectra under varying magnetic fields. Traces measured with different fields are offset by an amount that is proportional to the field.
  • Figure 3: Coherence times for different magnetic fields obtained by means of spectral hole burning (red triangles) and free induction decay (black dots). The insets show two measurement examples. Temperatures are 1.75 K and 2.22 K, respectively, explaining the slight difference between the results. The dashed lines are fits based on a spectral diffusion model. Error bars are calculated considering a laser linewidth uncertainty of $\pm$ 50 kHz.