Hybrid metal-semiconductor quantum dots for analog quantum simulation of Kondo lattice models : submicron ohmic contact to InAs quantum wells

Semiconductor quantum dot arrays have provided controllable realizations of effective Hamiltonians for understanding correlated electron behavior, however, intrinsic dot-to-dot inhomogeneity has been a challenge in efforts to scale up. A new type of hybrid metal-semiconductor quantum dot with a quasi-continuous level spectrum of a nanoscale metal island enables each site to behave essentially identically, while retaining the tunability of the intersite coupling. Recent experiments on a pair of hybrid metal-GaAs quantum dots investigated a quantum critical point (QCP) between competing ‘charge’-Kondo ground states[1]. The inhomogeneous contact morphology in GaAs forced these dots to be a few-microns wide, limiting investigations of the QCP to electron temperatures of 50 mK and below. Fermi level pinning in InAs provides a path for designing submicron hybrid dots with higher charging energies. We report the fabrication and characterization of hybrid metal-InAs quantum dots, featuring a submicron metallic island with tunable couplings[2] to macroscopic reservoirs. Scaling this to many such sites will allow simulating Kondo lattice models for explaining lattice coherence in heavy-fermion materials.

1. Pouse, W. et al. Nat. Phys. 19, 492–499 (2023)

2. Hsueh, C.L., Sriram, P. et al. Phys. Rev. B 105, 195303 (2022)