Estrada Saldaña Juan Carlos, Vekris Alexandros, Pavešić Luka, Krogstrup Peter, Žitko Rok, Grove-Rasmussen Kasper, Nygård Jesper
Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark.
Sino-Danish College (SDC), University of Chinese Academy of Sciences, Beijing, China.
Nat Commun. 2022 Apr 26;13(1):2243. doi: 10.1038/s41467-022-29634-5.
Cooper pairing and Coulomb repulsion are antagonists, producing distinct energy gaps in superconductors and Mott insulators. When a superconductor exchanges unpaired electrons with a quantum dot, its gap is populated by a pair of electron-hole symmetric Yu-Shiba-Rusinov excitations between doublet and singlet many-body states. The fate of these excitations in the presence of a strong Coulomb repulsion in the superconductor is unknown, but of importance in applications such as topological superconducting qubits and multi-channel impurity models. Here we couple a quantum dot to a superconducting island with a tunable Coulomb repulsion. We show that a strong Coulomb repulsion changes the singlet many-body state into a two-body state. It also breaks the electron-hole energy symmetry of the excitations, which thereby lose their Yu-Shiba-Rusinov character.
库珀对和库仑排斥是相互对立的，它们在超导体和莫特绝缘体中产生不同的能隙。当超导体与量子点交换未配对电子时，其能隙由双态和单态多体状态之间的一对电子 - 空穴对称的汤川 - 芝 - 鲁西诺夫激发填充。在超导体中存在强库仑排斥的情况下，这些激发的命运尚不清楚，但在诸如拓扑超导量子比特和多通道杂质模型等应用中很重要。在这里，我们将一个量子点耦合到一个具有可调库仑排斥的超导岛。我们表明，强库仑排斥将单态多体状态转变为双体状态。它还打破了激发的电子 - 空穴能量对称性，从而使它们失去了汤川 - 芝 - 鲁西诺夫特性。
