Growing extended Laughlin states in a quantum gas microscope: A patchwork construction

The study of fractional Chern insulators and their exotic anyonic excitations poses a major challenge in current experimental and theoretical research. Quantum simulators, in particular ultracold atoms in optical lattices, provide a promising platform to realize, manipulate, and understand such systems with a high degree of controllability. Recently, an atomic <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi>ν</a:mi><a:mo>=</a:mo><a:mstyle scriptlevel="1" displaystyle="false"><a:mn>1</a:mn></a:mstyle><a:mo>/</a:mo><a:mstyle scriptlevel="1" displaystyle="false"><a:mn>2</a:mn></a:mstyle></a:mrow></a:math> Laughlin state has been realized experimentally for a small system of two particles on <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:mrow><f:mn>4</f:mn><f:mo>×</f:mo><f:mn>4</f:mn></f:mrow></f:math> sites [Léonard , ]. The next challenge concerns the preparation of Laughlin states in extended systems, ultimately giving access to anyonic braiding statistics or gapless chiral edge-states in systems with open boundaries. Here, we propose and analyze an experimentally feasible scheme to grow larger Laughlin states by connecting multiple copies of the already-existing <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:mrow><g:mn>4</g:mn><g:mo>×</g:mo><g:mn>4</g:mn></g:mrow></g:math> system. First, we present a minimal setting obtained by coupling two of such patches, producing an extended <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mrow><h:mn>8</h:mn><h:mo>×</h:mo><h:mn>4</h:mn></h:mrow></h:math> system with four particles. Then, we analyze different preparation schemes, setting the focus on two shapes for the extended system, and discuss their respective advantages: While growing striplike lattices could give experimental access to the central charge, squarelike geometries are advantageous for creating quasihole excitations in view of braiding protocols. We highlight the robust quantization of the fractional quasihole charge upon using our preparation protocol. We benchmark the performance of our patchwork preparation scheme by comparing it to a protocol based on coupling one-dimensional chains. We find that the patchwork approach consistently gives higher target-state fidelities, especially for elongated systems. The results presented here pave the way towards near-term implementations of extended Laughlin states in quantum gas microscopes and the subsequent exploration of exotic properties of topologically ordered systems in experiments. Published by the American Physical Society 2024