arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1807.08809cond-mat.mes-hall
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近藤共振冻结电荷的观测

Observation of the frozen charge of a Kondo resonance

M. M. Desjardins, J. J. Viennot, M. C Dartiailh, L. E. Bruhat, M. R. Delbecq, M. Lee, M. -S. Choi, A. Cottet, T. Kontos

摘要:

在纳米尺度上控制电子状态的能力有助于我们对凝聚态的现代理解。特别是,量子点电路代表了研究强电子相关性的模型系统,其缩影是近藤效应。在这里,我们表明,电路量子电动力学架构可以用来研究这样的多体现象的内部自由度。我们将一个量子点耦合到一个高精细度的微波腔中,以前所未有的灵敏度测量量子点的电子压缩性,即量子点容纳电荷的能力。因为它只对应于电子系统的电荷响应,这个量不等于电导,电导一般涉及其他自由度,如自旋。通过在近藤制度进行双电导/压缩性测量,我们直接揭示了这种特殊的电子转移机制的电荷动力学。引人注目的是,近藤共振,在传输测量中可见,是透明的高精细腔中捕获的微波光子。这表明,在这样的多体共振中,有限传导是由库仑相互作用冻结的电荷实现的。这种以前难以捉摸的电荷动力学冻结与自由电子气体的物理形成鲜明对比。我们的设置突出了电路量子电动力学架构的力量来研究凝聚态问题。腔量子电动力学的工具可以应用于其他类型的多体关联介观电路,为费米子-玻色子问题的量子模拟提供了一个很有前途的平台。

英文摘要:

The ability to control electronic states at the nanoscale has contributed to our modern understanding of condensed matter. In particular, quantum dot circuits represent model systems for the study of strong electronic correlations, epitomized by the Kondo effect. Here, we show that circuit Quantum Electrodynamics architectures can be used to study the internal degrees of freedom of such a many-body phenomenon. We couple a quantum dot to a high finesse microwave cavity to measure with an unprecedented sensitivity the dot electronic compressibility i.e. the ability of the dot to accommodate charges. Because it corresponds solely to the charge response of the electronic system, this quantity is not equivalent to the conductance which involves in general other degrees of freedom such as spin. By performing dual conductance/compressibility measurements in the Kondo regime, we uncover directly the charge dynamics of this peculiar mechanism of electron transfer. Strikingly, the Kondo resonance, visible in transport measurements, is transparent to microwave photons trapped in the high finesse cavity. This reveals that, in such a many body resonance, finite conduction is achieved from a charge frozen by Coulomb interaction. This previously elusive freezing of charge dynamics is in stark contrast with the physics of a free electron gas. Our setup highlights the power of circuit quantum electrodynamics architectures to study condensed matter problems. The tools of cavity quantum electrodynamics could be used in other types of mesoscopic circuits with many-body correlations and bring a promising platform to perform quantum simulation of fermion-boson problems.

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