Experimental Realization of a Dirac Monopole through the Decay of an Isolated Monopole

Abstract

We experimentally observe the decay dynamics of deterministically created isolated monopoles in spin-1 Bose-Einstein condensates. As the condensate undergoes a change between magnetic phases, the isolated monopole gradually evolves into a spin configuration hosting a Dirac monopole in its synthetic magnetic field. We characterize in detail the Dirac monopole by measuring the particle densities of the spin states projected along different quantization axes. Importantly, we observe the spontaneous emergence of nodal lines in the condensate density that accompany the Dirac monopole. We also demonstrate that the monopole decay accelerates in weaker magnetic field gradients.

Rotating Atomic Quantum Gases with Light-Induced Azimuthal Gauge Potentials and the Observation of the Hess-Fairbank Effect

“…2 data and "B" indicates g = 0, for δ/2π = 100 and 500 Hz in Fig. 4, respectively , where coreless vortices [31], monopoles [32][33][34][35], 2D [36,37] and 3D skyrmions [38], and the geometric Hall effect [39] are demonstrated. Furthermore, 2D skyrmions [40] and spin monopoles [41] with pulses of Raman LG beams are achieved.…”

Critical Spin Superflow in a Spinor Bose-Einstein Condensate

“…The questions regarding superflow stability become more interesting when a superfluid has internal spin degrees of freedom [2]. A superfluid has multiple superflow channels for mass and spin, and their interplay may allow new types of topological excitations, such as fractionalized quantum voritces [3-6] and spin-textured solitons [7-9], possibly leading to qualitatively different dissipation dynamics [10][11][12]. Furthermore, the mixed mass and spin characters might give rise to ambiguities in the unique determination of a critical velocity, particularly, when a system has spin-orbit coupling [13,14].Critical spin superflow phenomena were first explored in experiments using superfluid helium-3, with the observation of phase slippage in a spin current [15], and recently using two-component atomic Bose-Einstein condensate (BEC) systems, which can be regarded as effective spin-1/2 superfluids, demonstrating counterflow instability [16][17][18].…”

“…The questions regarding superflow stability become more interesting when a superfluid has internal spin degrees of freedom [2]. A superfluid has multiple superflow channels for mass and spin, and their interplay may allow new types of topological excitations, such as fractionalized quantum voritces [3][4][5][6] and spin-textured solitons [7][8][9], possibly leading to qualitatively different dissipation dynamics [10][11][12]. Furthermore, the mixed mass and spin characters might give rise to ambiguities in the unique determination of a critical velocity, particularly, when a system has spin-orbit coupling [13,14].…”

Decay of a Quantum Knot

“…Upon including the spin degrees of freedom, the internal symmetries of the gas become plentiful, allowing for a diverse set of excitations. For example, in spinor BECs there can be several types of vortices [4][5][6][7][8][9], skyrmions [10][11][12][13][14], monopoles [15][16][17][18][19], and quantum knots [20,21].Topologically stable knots are classified by a linking number (or Hopf charge) Q, which counts the number of times each preimage loop of the order parameter is linked with every other such loop [22]. In Ref.…”