Erratum: Half-Quantum Vortices in an Antiferromagnetic Spinor Bose-Einstein Condensate [Phys. Rev. Lett.115, 015301 (2015)]

Abstract

We have found that one of the details on the spin-dependent phase-contrast imaging method is incorrectly presented in the text. The frequency of the probe light was detuned by −20 MHz from the 3S 1=2 jF ¼ 1i → 3P 3=2 jF 0 ¼ 2i transition, not the 3S 1=2 jF ¼ 1i → 3P 1=2 jF 0 ¼ 2i transition. In the abstract and the text, the gapless magnon excitations associated with the observed spin fluctuations are described as transverse, but they should be referred to as axial magnons [1]. We observed no population of the m z ¼ 0 component in the antiferromagnetic phase. This nomenclatural correction dose not affect the results and conclusion of the Letter.

Core Structure and Non-Abelian Reconnection of Defects in a Biaxial Nematic Spin-2 Bose-Einstein Condensate

“…In a uniaxial nematic (UN), the order parameter is cylindrically symmetric around a locally defined axis. It also exhibits a twofold discrete symmetry under reversal of the cylinder axis, which leads to half-quantum vortices (HQVs) in atomic spinor BoseEinstein condensates (BECs) [6][7][8][9] and superfluid liquid 3 He [10], and to π disclinations in liquid crystals [1,2]. In a biaxial nematic (BN), also the cylindrical symmetry is broken into the fully discrete symmetry of a rectangular brick, with dramatic consequences: the BN is the simplest order parameter that supports non-Abelian vortices that do not commute [5,11].…”

“…Recent efforts in spin-1 BECs have led to the in situ observation of a singly quantized vortex splitting into a pair of HQVs [9], confirming theoretical prediction [8], and to controlled preparation of coreless-vortex textures [26][27][28], the analogs of Dirac [22] and 't Hooft-Polyakov [29] monopoles, and particlelike solitons [30]. Our results for spin-2 reveal a defect-structure phenomenology considerably richer than that in the spin-1 BECs [8,[31][32][33][34].…”

Black-hole lasing in coherently coupled two-component atomic condensates

“…From the experimental point of view, a spin excitation wavepacket can be created in the condensate by generalizing standard Bragg techniques [43] to the spinful case. A suitable tayloring of the polarization of the Bragg beams can be used to suppress the parasitic excitation of density excitations [44] and the time-evolution of the spatial spin density profile can be detected with in situ techniques [35]. Even though our predictions can be in principle verified in single-shot experiments of the condensate dynamics, the deterministic nature of the Bragg scattering process allows to increase the signal-to-noise ratio by averaging over many shots of the same experiment.…”

“…As in the previous case, experimental information can be retrieved from the spatial spin density profiles of the atomic cloud, as obtained by spin-dependent imaging techniques [35]. If needed, a large number of such spin densities could be combined to get information on the spin-density correlation function.…”

“…On the other hand, using a two-photon Raman coupling allows to keep the mean-field dynamics simple and wellcontrolled without the need for a spatially dependent interaction parameters [14]. Finally, our theoretical study focuses on the spin density in the atomic cloud as the main observable, for which advanced imaging techniques offer direct in situ experimental access [34,35].…”