Quantum Dot Arrays for Analog Quantum Simulation

Semiconductor-based quantum dot arrays are versatile platforms for analog quantum simulations, potentially offering insights into classically intractable many-body quantum phenomena with fewer resources compared to digital processors. The ability to engineer a variety of interesting regimes has led to the demonstration of exotic phases of matter, from Mott insulators and Nagaoka ferromagnetism to implementations of Heisenberg spin-chains and signatures of resonating valence bonds. However, for quantum advantage, large scale systems and new tuning strategies are required. Here, we present advancements in this direction in a 2x4 Ge-based quantum dot array. We apply digital state preparation and read-out schemes in combination with precise analog time evolution to the observation of magnon dynamics in a disordered system. Here magnons represent spin excitations traveling through the array via nearest-neighbor exchange interactions, amidst disorder provided by random effective g-factors in each dot, typical for holes in Ge.<br/>We achieve exchange tunability up to 500 MHz, surpassing disorder by a factor of 50 at our operating magnetic field, while mitigating exchange crosstalk through a novel compensation method. For state preparation and read-out we leverage the intrinsic features of our Hamiltonian to initialize target spin-states and extract single-site spin-up probabilities across the array. This enables us to track magnon evolution in tailored configurations, from chains to rings.<br/>Our experiment bridges digital single qubit operation with many-body physics concepts, indicating progress towards large-scale analog simulators and realistic near-term applications of semiconductor quantum dot systems.