We present the first experimental realization and characterization of two-dimensional Skyrmions and half-Skyrmions in a spin-2 Bose-Einstein condensate. The continuous rotation of the local spin of the Skyrmion through an angle of pi (and half-Skyrmion through an angle of pi/2) across the cloud is confirmed by the spatial distribution of the three spin states as parametrized by the bending angle of the l vector. The winding number w = (0,1,2) of the internal spin states comprising the Skyrmions is confirmed through matter-wave interference.

We report an error in the representation of the local spin, or ' vector, [Eq. (2)] of both the Skyrmion and half-Skyrmion in our Letter. We made the assumption that the three-component spin texture created in the F ¼ 2 manifold of 87 Rb and described by Eq. (1),was an effective spin-1 system composed of states: j2; 2i, j2; 0i, j2; À2i. It was further assumed that this pseudo-spin-1 system was equivalent to one consisting of spin states: j2; 1i, j2; 0i, j2; À1i.We presented the following ' vector for our spin textures:'ðrÞ ¼ẑ cosðrÞ þ sinðrÞðx cos' þŷ sin'Þ;where nðrÞ is the density of the cloud, (r, ') are polar coordinates, and ðrÞ is the bending angle. For the spin textures we created, Eq. (2) is only valid if both of the above assumptions hold. A full calculation of the expectation value of the local spin, h^Fi ¼', using the spin-2 order parameter of Eq. (1) and the spin-2 angular momentum spin matrices does not produce the ' vector of Eq. (2). As a result, the plots of the local spin, Figs. 1(e) and 2(e), are incorrect. All other representations of the data are based on the wave function, Eq. (1), and are still valid. In light of this error, it is not clear whether the classification of these spin textures as a Skyrmion and half-Skyrmion is still appropriate. PRL

We use Raman-detuned laser pulses to achieve spatially varying control of the amplitude and phase of the spinor order parameter of a Bose-Einstein condensate. We present experimental results confirming precise radial and azimuthal control of amplitude and phase during the creation of vortex-antivortex superposition states.

Using the technique of point source atom interferometry (PSI), we characterize the sensitivity of a multi-axis gyroscope based on free-space Raman interrogation of a single source of cold atoms in a glass vacuum cell. The instrument simultaneously measures the acceleration in the direction of the Raman laser beams and the projection of the rotation vector onto the plane perpendicular to that direction. The sensitivities for the magnitude and direction of the rotation vector measurement are 0.033 • /s and 0.27 • with one second averaging time, respectively. The fractional acceleration sensitivity δg/g is 1.6 × 10 −5 / √ Hz. The sensitivity could be improved by increasing the Raman interrogation time, allowing the cold-atom cloud to expand further, correcting the fluctuations in the initial cloud shape, and reducing sources of technical noise. The PSI technique resolves a rotation vector in a plane by measuring a phase gradient. This two-dimensional rotation sensitivity may be specifically important for applications such as tracking the precession of a rotation vector and gyrocompassing.

We show that micro-machined non-evaporable getter pumps (NEGs) can extend the time over which laser cooled atoms can be produced in a magneto-optical trap (MOT), in the absence of other vacuum pumping mechanisms. In a first study, we incorporate a silicon-glass microfabricated ultra-high vacuum (UHV) cell with silicon etched NEG cavities and alumino–silicate glass (ASG) windows and demonstrate the observation of a repeatedly-loading MOT over a 10 min period with a single laser-activated NEG. In a second study, the capacity of passive pumping with laser activated NEG materials is further investigated in a borosilicate glass-blown cuvette cell containing five NEG tablets. In this cell, the MOT remained visible for over 4 days without any external active pumping system. This MOT observation time exceeds the one obtained in the no-NEG scenario by almost five orders of magnitude. The cell scalability and potential vacuum longevity made possible with NEG materials may enable in the future the development of miniaturized cold-atom instruments.

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We demonstrate a waveplate for a pseudo-spin-1/2 Bose-Einstein condensate using a two-photon Raman interaction. The angle of the waveplate is set by the relative phase of the optical fields, and the retardance is controlled by the pulse area. The waveplate allows us to image maps of the Stokes parameters of a BoseEinstein condensate and thereby measure its relative ground state phase. We demonstrate the waveplate by measuring the Stokes parameters of a coreless vortex.

A coherent two-photon optical Raman interaction in a pseudo-spin-1/2 Bose–Einstein condensate (BEC) serves as a q-plate for atoms, converting spin to orbital angular momentum. This Raman q-plate has a singular pattern in its polarization distribution in analogy to the singular birefringent q-plates used in singular optics. The vortex winding direction and magnitude as well as the final spin state of the BEC depend on the initial spin state and the topology of the optical Raman q-plate beams. Drawing on the mathematical and geometric foundations of singular optics, we derive the equivalent Jones matrix for this Raman q-plate and use it to create and characterize atomic spin singularities in the BEC that are analogous to optical C-point singularities in polarization. By tuning the optical Raman parameters, we can generate a coreless vortex spin texture which contains every possible superposition in a two-state system. We identify this spin texture as a full-Bloch BEC since every point on the Bloch sphere is represented at some point in the cross section of the atomic cloud. This spin–orbit interaction and the spin textures it generates may allow for the observation of interesting geometric phases in matter waves and lead to schemes for topological quantum computation with spinor BECs.