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Register a new userPhotoassociation spectroscopy of weakly bound $^{87}Rb_{2}$ molecules near $5P_{1/2} +5S_{1/2}$ threshold by optical Bragg scattering in Bose-Einstein condensates
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We report the high resolution photoassociation (PA) spectroscopy of a $^{87}Rb$ Bose-Einstein condensate (BEC) to excited molecular states near the dissociation limit of $5P_{1/2} +5S_{1/2}$ by optical Bragg scattering. Since the detection of optical Bragg scattering in BEC has a high signal-noise ratio, we obtain the high resolution PA spectrum of excited molecular states in the range of $pm1$ GHz near the dissociation limit of $5P_{1/2} +5S_{1/2}$. We compare the results with the conventional method of trap loss and show that the results agree each other very well. Many interesting phenomena of excited molecular states are observed, such as light-induced frequency shift and the anomalous strong bound molecular lines at the atomic transition from $|F=1rangle$ to $|F^{prime}=2rangle$. The observed excited molecular states in the range of $pm1$ GHz near the dissociation limit of $5P_{1/2} +5S_{1/2}$ are never reported before, which will help to further improve the long range bound state models near the dissociation limit.
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We observe a hyperfine anomaly in the measurement of the hyperfine splitting of the 6S_{1/2} excited level in rubidium. We perform two step spectroscopy using the 5S_{1/2}->5P_{1/2}->6S_{1/2} excitation sequence. We measure the splitting of the 6S1/2 level and obtain for the magnetic dipole constants of ^{85}Rb and ^{87}Rb A = 239.18(4) MHz and A=807.66(8) MHz, respectively. The hyperfine anomaly difference of_{87}delta_{85}=-0.0036(2) comes from the Bohr Weisskopf effect: a correction to the point interaction between the finite nuclear magnetization and the electrons, and agrees with that obtained in the 5S_{1/2} ground state.
We experimentally investigate the dynamic instability of Bose-Einstein condensates in an optical ring resonator that is asymmetrically pumped in both directions. We find that, beyond a critical resonator-pump detuning, the system becomes stable regardless of the pump strength. Phase diagrams and quenching curves are presented and described by numerical simulations. We discuss a physical explanation based on a geometric interpretation of the underlying nonlinear equations of motion.
We observe long-range $^{85}$Rb and $^{87}$Rb (24$D$+5$S_{1/2}$) Rydberg molecules for eight different spin couplings, with binding energies up to 440~MHz and sub-percent relative uncertainty. Isotopic effects of the molecular binding energies arise from the different masses and nuclear spins. Because the vibrational states involve different spin configurations and cover a wide range of internuclear separations, the states have different dependencies on the $s$-wave and $p$-wave scattering phase shifts for singlet and triplet scattering. Fitting the spectroscopic data, we comprehensively determine all four scattering length functions over the relevant energy range as well as the zero-energy scattering lengths of the two $s$-wave channels. Our unusually high temperature and low density (180 $mu$K, 1 $times$ 10$^{11}$ cm$^{-3}$) suggest that the molecule excitation occurs through photoassisted collisions.
We analytically and numerically investigate the ground state of the spin-orbit coupled spin-1 Bose-Einstein condensates in an external parabolic potential. When the spin-orbit coupling strength $kappa$ is comparable with that of the trapping potential, the density distribution centers of different components of the spinor condensate deviate evidently from the trap center in the plane wave and stripe phases. When $kappagg1$, the magnitude of this deviation decreases as $kappa$ is getting larger and larger. Correspondingly, periphery half-skyrmions textures arise. This deviation can be reflected by the non-uniform magnetic moment in the $z$ direction, $mathcal{F}_z$. With the manipulation of the external trap, the local magnitude of $mathcal{F}_z$ can be increased evidently. This kind of increase of $mathcal{F}_z$ is also observed in the square vortex lattice phase of the condensate.
We present a compact experimental apparatus for Bose-Einstein condensation of $^{87}$Rb in the $|F = 2, m_F = +2rangle$ state. A pre-cooled atomic beam of $^{87}$Rb is obtained by using an unbalanced magneto-optical trap, allowing controlled transfer of trapped atoms from the first vacuum chamber to the science chamber. Here, atoms are transferred to a hybrid trap, as produced by overlapping a magnetic quadrupole trap with a far-detuned optical trap with crossed beam configuration, where forced radiofrequency evaporation is realized. The final evaporation leading to Bose-Einstein condensation is then performed by exponentially lowering the optical trap depth. Control and stabilization systems of the optical trap beams are discussed in detail. The setup reliably produces a pure condensate in the $|F = 2, m_F = +2rangle$ state in 50 s, which include 33 s loading of the science magneto-optical trap and 17 s forced evaporation.
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