Coulomb blockade in an atomically thin quantum dot coupled to a tunable Fermi reservoir
Coulomb blockade in an atomically thin quantum dot coupled to a tunable Fermi reservoir
复制标题
DOI：
10.1038/s41565-019-0402-5
复制
发表时间：
2019-05-01
影响因子：
38.3
通讯作者：
Gerardot, Brian D.
中科院分区：
文献类型：
--
作者：
Brotons-Gisbert, Mauro;Branny, Artur;Gerardot, Brian D.
在量子受限态和附近的非定域态费米库之间的粒子的门可调谐量子力学隧穿，支撑了自旋电子学和固态量子光学的许多进展。典型的例子是通过隧道势垒将半导体量子点与门控触点分开。这就实现了库仑封锁，即电子或空穴可以一个接一个地装入量子点（1,2）的现象。根据隧道耦合强度（3,4），这种能力可以促进单自旋量子比特（1,2,5）或约束自旋和费米储层之间的相干多体相互作用（6,7）。范德华（vdW）异质结构，其中广泛的独特的原子层可以很容易地结合在一起，为工程相干量子限制自旋（8,9），隧道障碍降低到原子极限（10）或费米库超越传统的平面态密度（11）提供了新的前景。然而，需要在单粒子水平上对vdW纳米结构（12-16）进行栅极控制，以释放其潜力。在这里，我们报道了一种vdW异质结构中的库仑封锁，该异质结构由过渡金属二硫化物量子点通过原子薄的六方氮化硼（hBN）隧道势垒耦合到石墨烯触点。多亏了可调谐的费米储层，我们可以确定地将单个电子或单个空穴加载到量子点中。我们观察到由局域量子点态和非局域连续态组成的杂化激子通过原子薄的隧道势垒产生了超强的自旋守恒隧道耦合。探测外加磁场中的带电激子，我们观察到大的回旋磁比（类似于8）。我们的研究结果为研究近藤物理的新体制或vdW异质结构平台中的孤立量子比特的工程下一代设备奠定了基础。
Gate-tunable quantum-mechanical tunnelling of particles between a quantum confined state and a nearby Fermi reservoir of delocalized states has underpinned many advances in spintronics and solid-state quantum optics. The prototypical example is a semiconductor quantum dot separated from a gated contact by a tunnel barrier. This enables Coulomb blockade, the phenomenon whereby electrons or holes can be loaded one-by-one into a quantum dot(1,2). Depending on the tunnel-coupling strength(3,4), this capability facilitates single spin quantum bits(1,2,5) or coherent many-body interactions between the confined spin and the Fermi reservoirs(6,7). Van der Waals (vdW) heterostructures, in which a wide range of unique atomic layers can easily be combined, offer novel prospects to engineer coherent quantum confined spins(8,9), tunnel barriers down to the atomic limit(10) or a Fermi reservoir beyond the conventional flat density of states(11). However, gate-control of vdW nanostructuresu(12-16) at the single particle level is needed to unlock their potential. Here we report Coulomb blockade in a vdW heterostructure consisting of a transition metal dichalcogenide quantum dot coupled to a graphene contact through an atomically thin hexagonal boron nitride (hBN) tunnel barrier. Thanks to a tunable Fermi reservoir, we can deterministically load either a single electron or a single hole into the quantum dot. We observe hybrid excitons, composed of localized quantum dot states and delocalized continuum states, arising from ultra-strong spin-conserving tunnel coupling through the atomically thin tunnel barrier. Probing the charged excitons in applied magnetic fields, we observe large gyromagnetic ratios (similar to 8). Our results establish a foundation for engineering next-generation devices to investigate either novel regimes of Kondo physics or isolated quantum bits in a vdW heterostructure platform.