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Strong correlations give rise to exotic phenomena which typically originate from the electron-electron interactions in quantum materials. One of the central problems that reflect strong correlations is the Kondo effect, where localized impurity spins are screened by conduction electrons realizing the Kondo singlet. Meanwhile, open quantum systems have witnessed a remarkable development in recent years. In particular, non-Hermitian (NH) physics naturally arises such as systems with gain and loss and has been intensively investigated thanks to the advancement in dissipation engineering with ultracold atoms. As the many-body physics of the Kondo effect in closed systems is well understood, here we ask the following question for open systems: how does the renormalization effect due to strong correlations affect the nature of dissipation?

In this talk, we analyze the competition between strong correlations and dissipation in quantum impurity systems from the Kondo regime to the valence fluctuation regime by developing a slave-boson theory for a non-Hermitian Anderson impurity model with one-body loss [1]. Notably, in the non-Hermitian Kondo regime, strong correlations qualitatively change the nature of dissipation through renormalization effects, where the effective one-body loss is suppressed and emergent many-body dissipation characterized by the complex-valued hybridization is generated. We unveil the mechanism of a dissipative quantum phase transition of the Kondo state on the basis of this renormalization effect, which counterintuitively enhances the lifetime of the impurity against loss. We also find a crossover from the non-Hermitian Kondo regime to the valence fluctuation regime dominated by one-body dissipation. Our results can be tested in a wide variety of setups such as quantum dots coupled to electronic leads and quantum point contacts in ultracold Fermi gases.

[1] Kazuki Yamamoto, Masaya Nakagawa, and Norio Kawakami arXiv:2408.XXXXX to be submitted.

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