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arXiv 1506.04539cond-mat.quant-gas
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振动光晶格中的扩展玻色-哈伯德模型

Extended Bose-Hubbard model in a shaken optical lattice

Jiao Miao

摘要:

研究了在振动光晶格中具有次近邻跳跃的扩展玻色-哈伯德模型。我们展示了平均场相图如何随NNN跳变幅度$t_{2}$的变化而演化,这可以很容易地通过振荡幅度来调谐。随着$t_{2}$的增加,在Mott lobs的底部出现$Z_{2}$ -破胶超流体($Z_{2}$ SF)相。确定了正常超流、$Z_{2}$ SF和莫特绝缘体(MI)相之间的三临界点。我们进一步证明了三临界点可以调谐到莫特波瓣的尖端,在这种情况下,一个新的临界行为已被预测。在随机相位近似下,得到了三个相态的激发谱,这些谱表明了相变是如何发生的。

英文摘要:

We study an extended Bose-Hubbard model with next-nearest-neighbor (NNN) hopping in a shaken optical lattice. We show how mean-field phase diagram evolves with the change of NNN hopping amplitude $t_{2}$, which can be easily tuned via shaking amplitude. As $t_{2}$ increases, a $Z_{2}$-symmetry-breaking superfluid ($Z_{2}$SF) phase emerges at the bottom of the Mott lobs. The tricritical points between normal superfluid, $Z_{2}$SF, and Mott insulator (MI) phases are identified. We further demonstrate the tricritical point can be tuned to the tip of the Mott lobe, in which case a new critical behavior has been predicted. Within random-phase approximation, excitation spectra in the three phases are obtained, which indicate how the phase transitions occur.

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