Spectroscopy of the 1001-nm transition in atomic dysprosium

We report on spectroscopy of cold dysprosium atoms on the $1001\text{−}\mathrm{nm}$ transition and present measurements of the excited-state lifetime which is at least $87\left(7\right)\mathrm{ms}$ long. Due to the long excited-state lifetime we are able to measure the ratio of the excited-state polarizability to the ground-state polarizability at $1064\mathrm{nm}$ to be 0.83(0.13) by parametric heating in an optical dipole trap. In addition we measure the isotope shifts of the three most abundant bosonic isotopes of dysprosium on the $1001\text{−}\mathrm{nm}$ transition with an accuracy better than $30\mathrm{kHz}$.

Figure 1

(a) Excerpt of Dy energy levels for total angular momenta $\mathrm{J}=8,9,\mathrm{and}10$ [10]. Even- (odd-) parity levels are drawn in red (black). The electron configuration of the ground state and of the excited state of the $1001\text{−}\mathrm{nm}$ transition are written next to the corresponding levels. (b) Experimental setup. (c) $1001\text{−}\mathrm{nm}$ laser system. DDS: direct digital synthesis; FSR: free spectral range.

Figure 2

Exemplary spectra of the $1001\text{−}\mathrm{nm}$ transition for ${}^{160}\mathrm{Dy}$, ${}^{162}\mathrm{Dy}$, and ${}^{164}\mathrm{Dy}$.

Figure 3

(a) Measurement sequence for the number of excited-state atoms $N_e$ after a variable holding time, where GSR refers to the resonant 421-nm beam, which is used to remove the ground-state atoms. MOD refers to modulation of the ODT intensity, and IMG to absorption imaging. The blue data points are the measured averaged excitation ratios $N_e/N_t$ versus the holding time after the first RAP in the sequence. The red line is the result of a fit with an exponential decay function with an offset to the data. The lifetime is ${\tau }_{1001}\ge 87\left(7\right)\mathrm{ms}$. Inset: beam setup for the lifetime measurements. (b) Typical ODT intensity modulation at a frequency of $f_{\mathrm{MOD}}=1210\mathrm{Hz}$. (c) Sequence to measure $N_e$ after $60\mathrm{ms}$ modulation (MOD) of the ODT intensity. Parametric heating spectra for the excited state (top) and ground state (bottom).