Breaking inversion symmetry in a state-dependent honeycomb lattice: Artificial graphene with tunable band gap

TL;DR

This paper introduces a method to control the geometry and energy gap of a honeycomb lattice by rotating the atomic quantization axis, enabling tunable artificial graphene properties.

Contribution

It presents a novel technique for adjusting the sublattice energy offset in a state-dependent honeycomb lattice, allowing continuous tuning between different lattice geometries and opening a controllable band gap.

Findings

The energy offset can be tuned by rotating the quantization axis.

A band gap at Dirac points influences atom lifetimes in the second energy band.

Microwave spectroscopy confirms symmetry control of the lattice.

Abstract

Here, we present the application of a novel method for controlling the geometry of a state-dependent honeycomb lattice: The energy offset between the two sublattices of the honeycomb structure can be adjusted by rotating the atomic quantization axis. This enables us to continuously tune between a homogeneous graphene-like honeycomb lattice and a triangular lattice and to open an energy gap at the characteristic Dirac points. We probe the symmetry of the lattice with microwave spectroscopy techniques and investigate the behavior of atoms excited to the second energy band. We find a striking influence of the energy gap at the Dirac cones onto the lifetimes of atoms in the excited band.