Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France.
National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8563, Japan.
Nat Commun. 2017 Nov 22;8(1):1710. doi: 10.1038/s41467-017-01685-z.
The electron wave function experiences a phase modification at coherent transmission through a quantum dot. This transmission phase undergoes a characteristic shift of π when scanning through a Coulomb blockade resonance. Between successive resonances either a transmission phase lapse of π or a phase plateau is theoretically expected to occur depending on the parity of quantum dot states. Despite considerable experimental effort, this transmission phase behaviour has remained elusive for a large quantum dot. Here we report on transmission phase measurements across such a large quantum dot hosting hundreds of electrons. Scanning the transmission phase along 14 successive resonances with an original two-path interferometer, we observe both phase lapses and plateaus. We demonstrate that quantum dot deformation alters the sequence of phase lapses and plateaus via parity modifications of the involved quantum dot states. Our findings set a milestone towards an comprehensive understanding of the transmission phase of quantum dots.
电子波函数在通过量子点进行相干传输时会经历相位修饰。当扫描库仑阻塞共振时，这个传输相位会经历一个特征性的 π 相移。在连续的共振之间，根据量子点态的奇偶性，理论上预计会发生传输相位的 π 相移或相位平台。尽管已经进行了相当多的实验努力，但对于一个大型量子点，这种传输相位行为仍然难以捉摸。在这里，我们报告了在一个容纳数百个电子的大型量子点上进行的传输相位测量。我们使用原始的双通道干涉仪沿着 14 个连续的共振扫描传输相位，观察到了相位的 π 相移和平台。我们证明了量子点变形通过改变涉及的量子点态的奇偶性来改变相位的 π 相移和平台的顺序。我们的发现为全面理解量子点的传输相位迈出了重要的一步。
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