Institut für Experimentalphysik und Zentrum für Quantenphysik, Universität Innsbruck, 6020 Innsbruck, Austria.
Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA. Department of Physics and the Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG, UK.
Science. 2014 Jun 13;344(6189):1259-62. doi: 10.1126/science.1248402.
Quantum tunneling is at the heart of many low-temperature phenomena. In strongly correlated lattice systems, tunneling is responsible for inducing effective interactions, and long-range tunneling substantially alters many-body properties in and out of equilibrium. We observe resonantly enhanced long-range quantum tunneling in one-dimensional Mott-insulating Hubbard chains that are suddenly quenched into a tilted configuration. Higher-order tunneling processes over up to five lattice sites are observed as resonances in the number of doubly occupied sites when the tilt per site is tuned to integer fractions of the Mott gap. This forms a basis for a controlled study of many-body dynamics driven by higher-order tunneling and demonstrates that when some degrees of freedom are frozen out, phenomena that are driven by small-amplitude tunneling terms can still be observed.
量子隧穿是许多低温现象的核心。在强关联晶格系统中，隧穿负责诱导有效相互作用，长程隧穿极大地改变了平衡和非平衡状态下的多体性质。我们观察到一维莫特绝缘 Hubbard 链在突然倾斜配置下的共振增强长程量子隧穿。当每个晶格位置的倾斜调谐到莫特隙的整数分数时，通过更高阶隧穿过程在多达五个晶格位置上观察到的双占据位置的共振。这为通过高阶隧穿驱动的多体动力学的受控研究提供了基础，并表明当一些自由度被冻结时，仍然可以观察到由小振幅隧穿项驱动的现象。
