Speaker:  Dr. Tzu-Kan Hsiao, QuTech, Netherland

Time: 2:30PM, 1/12, 2021

Place; Room 019, NTHU department of physics

Title:
Quantum simulation of an antiferromagnetic Heisenberg spin chain with gate-defined quantum dots
 
Abstract:
Emergent phases of strongly-correlated fermions are of central interest in condensed matter physics. Quantum systems with engineered Hamiltonians can be used as simulators of such many-body systems to provide insights beyond the capabilities of classical computers. Magnetism naturally arises in the Mott-insulator regime of the Fermi-Hubbard model, where charges are localized and the spin degree of freedom remains. In this regime the occurrence of phenomena such as resonating valence bonds, frustrated magnetism, and spin liquids are predicted. However, to study such magnetic behaviour low-entropy, many-body spin states have to be prepared, and characterized.

In this experiment we show that gate-defined semiconductor quantum dots can be used to simulate quantum magnetism in the Mott-insulator regime. For this purpose we develop several experimental techniques including many-body spin-state preparation, singlet-triplet correlation measurements, and characterization of the quantum system with energy spectroscopy and global coherent oscillations. We use these techniques to tune and probe a homogeneously coupled Heisenberg spin chain formed in a linear array of four single-electron quantum dots, and find good agreement between experiment and numerical simulation. Our demonstrated control and techniques combined with flexibility of the quantum dot lattice geometry design opens new opportunities to simulate quantum magnetism, including spin liquid physics and quantum phase transitions.