A three-step laser excitation scheme is used to make absolute frequency measurements of highly excited nF 7/2 Rydberg states in 85 Rb for principal quantum numbers n=33–100. This work demonstrates the first absolute frequency measurements of rubidium Rydberg levels using a purely optical detection scheme. The Rydberg states are excited in a heated Rb vapour cell and Doppler-free signals are detected via purely optical means. All of the frequency measurements are made using a wavemeter that is calibrated against a Global Positioning System (GPS)-disciplined self-referenced optical frequency comb. We find that the measured levels have a very high frequency stability, and are especially robust against electric fields. The apparatus has allowed measurements of the states to an accuracy of 8.0 MHz. The new measurements are analysed by extracting the modified Rydberg–Ritz series parameters.
We report the measurement of absolute excitation frequencies of
87Rb to
nS and
nD Rydberg states. The Rydberg transition frequencies are obtained by observing electromagnetically induced transparency on a rubidium vapor cell. The accuracy of the measurement of each state is $\ensuremath{\lesssim}$1 MHz, which is achieved by frequency stabilizing the two diode lasers employed for the spectroscopy to a frequency comb and a frequency comb calibrated wavelength meter, respectively. Based on the spectroscopic data we determine the quantum defects of
87Rb, and compare it with previous measurements on
85Rb. We determine the ionization frequency from the
5S1/2(F=1) ground state of
87Rb to
1010.0291646(3)THz, providing the binding energy of the ground state with an accuracy improved by two orders of magnitude.
We report our measurements of the absolute transition frequencies of 5P3/2, F = 3 to nS and nD Rydberg states of 87Rb with high principal quantum numbers in a wide range of values (n = 45-124). The measurements were performed using Rydberg Electromagnetically Induced Transparency (EIT) in ladder-type three-level systems. We measure the transition frequencies with an accuracy of ≤ 2 MHz. We determine the values of the Rydberg-Ritz parameter for 87Rb from our experimental measurements of the transition frequencies. Our measurements of the absolute transition frequencies of the highly excited Rydberg states would be useful for diverse applications in quantum information processing, quantum simulation and quantum sensing with Rydberg atoms.
We present absolute-frequency measurements in ultracold
39K samples of the transitions from the
4s1/2 ground state to
np1/2 and
np3/2 Rydberg states. A global nonlinear regression of the
np1/2 and
np3/2 term values yields an improved wave number of 35009.8139710(22)${}_{\mathrm{sys}}{(3)}_{\mathrm{stat}}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ for the first ionization threshold of
39K and the quantum defects of the
np1/2 and
np3/2 series. In addition, we report the frequencies of selected one-photon transitions ${n}^{\ensuremath{'}}{s}_{1/2}\ensuremath{\leftarrow}n{p}_{3/2}, {n}^{\ensuremath{'}}{d}_{j}\ensuremath{\leftarrow}n{p}_{3/2}, {n}^{\ensuremath{'}}{f}_{{j}^{\ensuremath{'}}}\ensuremath{\leftarrow}n{d}_{j}$, and ${n}^{\ensuremath{'}}{g}_{{j}^{\ensuremath{'}}}\ensuremath{\leftarrow}n{f}_{j}$ and two-photon transitions $n{f}_{{j}^{\ensuremath{'}}}\ensuremath{\leftarrow}n{p}_{j}$ determined by millimeter-wave spectroscopy, where
j is the total angular-momentum quantum number. By combining the results from the laser and millimeter-wave spectroscopic experiments, we obtain improved values for the quantum defects of the
s1/2,d3/2,d5/2,fj, and
gj states. For the
dj series, the inverted fine structure was confirmed for $n\ensuremath{\ge}32$. The fine-structure splitting of the
f series is less than 100 kHz at
n=31, significantly smaller than the hydrogenic splitting, and the fine structure of the
g series is regular for $n\ensuremath{\ge}30$, with a fine-structure splitting compatible with the hydrogenic prediction. From the measured quantum defects of the
f and
g series we derive an estimate for the static dipole ${\ensuremath{\alpha}}_{\mathrm{d}}$ and quadrupole ${\ensuremath{\alpha}}_{\mathrm{q}}$ polarizabilities of the
K+ ion core. Additionally, the hyperfine splitting of the
4s1/2 ground state of
39K was determined to be 461.719700(5) MHz using radio-frequency spectroscopy and Ramsey-type interferometry.
We have measured the absolute frequency of the excited state transition 5P(3/2)-4D(5/2) in a (87)Rb atom with a femtosecond frequency comb, utilizing the recently developed spectroscopic technique of the double resonance optical pumping method. The absolute energy level of the 4D(5/2) state is determined by measuring the absolute frequency of the 5S(1/2)-5P(3/2) transition simultaneously. The hyperfine structure constants of the 4D(5/2) state are obtained by using the measured frequency. The magnetic dipole constant, A, is determined to be (-16.747+/-0.010) MHz with an uncertainty reduced 60-fold compared with a previous result. The electric quadrupole constant, B, is determined, for what is to our knowledge the first time, to be (4.149+/-0.059) MHz.