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Register a new userDifferential Light Shift Cancellation in a Magnetic-Field-Insensitive Transition of $^{87}$Rb
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We demonstrate near-complete cancellation of the differential light shift of a two-photon magnetic-field-insensitive microwave hyperfine (clock) transition in $^{87}$Rb atoms trapped in an optical lattice. Up to $95(2)%$ of the differential light shift is canceled while maintaining magnetic-field insensitivity. This technique should have applications in quantum information and frequency metrology.
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We present a method that uses radio-frequency pulses to cancel the quadrupole shift in optical clock transitions. Quadrupole shifts are an inherent inhomogeneous broadening mechanism in trapped ion crystals, limiting current optical ion clocks to work with a single probe ion. Cancelling this shift at each interrogation cycle of the ion frequency allows the use of $N>1$ ions in clocks, thus reducing the uncertainty in the clock frequency by $sqrt{N}$ according to the standard quantum limit. Our sequence relies on the tensorial nature of the quadrupole shift, and thus also cancels other tensorial shifts, such as the tensor ac stark shift. We experimentally demonstrate our sequence on three and seven $^{88}mathrm{Sr}^{+}$ ions trapped in a linear Paul trap, using correlation spectroscopy. We show a reduction of the quadrupole shift difference between ions to $approx20$ mHzs level where other shifts, such as the relativistic 2$^{mathrm{nd}}$ order Doppler shift, are expected to limit our spectral resolution. In addition, we show that using radio-frequency dynamic decoupling we can also cancel the effect of 1$^{mathrm{st}}$ order Zeeman shifts.
We report on the observation of ultracold heteronuclear Feshbach molecules. Starting with a $^{87}$Rb BEC and a cold atomic gas of $^{85}$Rb, we utilize previously unobserved interspecies Feshbach resonances to create up to 25,000 molecules. Even though the $^{85}$Rb gas is non-degenerate we observe a large molecular conversion efficiency due to the presence of a quantum degenerate $^{87}$Rb gas; this represents a key feature of our system. We compare the molecule creation at two different Feshbach resonances with different magnetic-field widths. The two Feshbach resonances are located at $265.44pm0.15$ G and $372.4pm1.3$ G. We also directly measure the small binding energy of the molecules through resonant magnetic-field association.
We present a method for accurate determination of atomic transition matrix elements at the 10^{-3} level. Measurements of the ac Stark (light) shift around magic-zero wavelengths, where the light shift vanishes, provide precise constraints on the matrix elements. We make the first measurement of the 5s-6p matrix elements in rubidium by measuring the light shift around the 421 nm and 423 nm zeros with a sequence of standing wave pulses. In conjunction with existing theoretical and experimental data, we find 0.3236(9) e a_0 and 0.5230(8) e a_0 for the 5s-6p_{1/2} and 5s-6p_{3/2} elements, respectively, an order of magnitude more accurate than the best theoretical values. This technique can provide needed, accurate matrix elements for many atoms, including those used in atomic clocks, tests of fundamental symmetries, and quantum information.
In this paper we discuss in detail an experimental scheme to test the universality of free fall (UFF) with a differential $^{87}$Rb / $^{85}$Rb atom interferometer applicable for extended free fall of several seconds in the frame of the STE-QUEST mission. This analysis focuses on suppression of noise and error sources which would limit the accuracy of a violation measurement. We show that the choice of atomic species and the correctly matched parameters of the interferometer sequence are of utmost importance to suppress leading order phase shifts. In conclusion we will show the expected performance of $2$ parts in $10^{15}$ of such an interferometer for a test of the UFF.
The electromagnetically induced transparency (EIT) observations in two $Lambda$-systems of $^{87}Rb$ atom, $|5^{2}S_{1/2} F=1rangle rightarrow |5^{2}P_{3/2} F=1rangle leftarrow |5^{2}S_{1/2} F=2rangle$ and $|5^{2}S_{1/2} F=1rangle rightarrow |5^{2}P_{3/2} F=2rangle leftarrow |5^{2}S_{1/2} F=2rangle$, have been investigated in detail and the results are found consistent with our proposed theoretical models. The second $Lambda$-system provides EIT signal with higher magnitude than the first system, both in absence and in presence of an applied magnetic field. The observed steeper slope of the EIT signal in presence of the magnetic field can enable one to achieve tight frequency locking of lasers using these EIT signals.
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