Adequacy of Si:P Chains as Fermi-Hubbard Simulators

TL;DR

This paper explores the potential of silicon dopant chains as analog quantum simulators for the fermionic extended Hubbard model, demonstrating robustness at higher temperatures and against disorder, thus offering a complementary approach to cold atom systems.

Contribution

It introduces a method to use atomically precise Si:P chains as Fermi-Hubbard simulators and analyzes their robustness under temperature and disorder variations.

Findings

Charge and spin correlations remain robust up to 4K.

Properties are strongly affected by interdonor distance R0.

Finite donor chains can simulate strongly correlated Hamiltonians.

Abstract

The challenge of simulating many-body models with analogue physical systems requires both experimental precision and very low operational temperatures. Atomically precise placement of dopants in Si permits the construction of nanowires by design. We investigate the suitability of these interacting electron systems as simulators of a fermionic extended Hubbard model on demand. We describe the single particle wavefunctions as a Linear Combination of Dopant Orbitals (LCDO). The electronic states are calculated within configuration interaction (CI). Due to the peculiar oscillatory behavior of each basis orbital, properties of these chains are strongly affected by the interdonor distance $R_0$, in a non-monotonic way. Ground state (T=0K) properties such as charge and spin correlations are shown to remain robust under temperatures up to 4K for specific values of $R_0$. The robustness of the model against disorder is also tested, allowing some fluctuation of the placement site around the target position. We suggest that finite donor chains in Si may serve as an analog simulator for strongly correlated model Hamiltonians. This simulator is, in many ways, complementary to those based on cold atoms in optical lattices---the trade-off between the tunability achievable in the latter and the survival of correlation at higher operation temperatures for the former suggests that both technologies are applicable for different regimes.