Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstrasse 2 D-30167, Hannover, Germany.
Phys Rev Lett. 2010 Jul 30;105(5):050402. doi: 10.1103/PhysRevLett.105.050402. Epub 2010 Jul 27.
We study the influence of the quadratic Zeeman effect on the Mott-insulator phases of hard-core 1D spin-3/2 fermions. We show that, contrary to spinor bosons, the quadratic Zeeman coupling preserves an SU(2)⊗SU(2) symmetry, leading for large-enough quadratic Zeeman coupling to an isotropic pseudo-spin-1/2 Heisenberg antiferromagnet. Decreasing the quadratic Zeeman coupling, this phase undergoes, depending on the scattering lengths, either a Kosterlitz-Thouless transition into a gapped dimerized phase or a commensurate-incommensurate transition into a gapless spin liquid. This rich phase diagram can be observed experimentally in four-component fermions in optical lattices under similar entropy constraints to those needed for Néel order in spin-1/2 gases.
我们研究了二次塞曼效应对硬芯一维自旋-3/2 费米子莫特绝缘体相的影响。我们表明，与旋量玻色子不同，二次塞曼耦合保持 SU(2)⊗SU(2) 对称性，对于足够大的二次塞曼耦合，导致各向同性赝自旋-1/2 海森堡反铁磁体。随着二次塞曼耦合的减小，根据散射长度，这个相要么经历一个进入有能隙的二聚化相的科斯特利茨-图尔过渡，要么经历一个进入无能隙的自旋液体的谐和-非谐过渡。在光学晶格中，四分量费米子在类似自旋-1/2 气体中奈尔有序所需的熵约束下，可以在实验中观察到这个丰富的相图。
