IAP Seminar(Quantum Simulations with Ge/SiGe 2x4 Quantum Dot Ladders)
Date : December 2, 2025 11:00 ~ 12:00
Speaker : Dr. Stefano Reale (QuTech & Kavli Institute of Nanoscience, Delft University of Technology, Delft, NL)
Professor : Prof. Dohun Kim
Location : 56-321
Quantum Simulations with Ge/SiGe 2x4 Quantum Dot Ladders
Gate-defined semiconductor quantum dot arrays are a promising platform for digital and analog quantum simulations due to their scalability and precise control capabilities [1].
I will present our recent progress in using a Ge/SiGe 2x4 quantum dot ladder as a platform for quantum simulation of spin physics, where exquisite control over individual spin qubits and their couplings enables us to engineer and probe many-body phenomena in a highly controllable solid-state setting.
I'll discuss three main experimental results: First, we demonstrate quantum walks of magnon (single-spin) and triplon (two-spin) excitations propagating through the array [2]. By dynamically tuning exchange interactions, we show how we can prepare these excitations on demand and control their propagation characteristics.
Second, we develop a many-body spectroscopy tool based on Ramsey interferometry and reconstruct the energy spectrum of spin chains with up to 8 spins. By adiabatic ramping, we achieve a one-to-one mapping from computational (Zeeman) basis states to many-body eigenstates. Analysis of the energy level statistics reveals signatures of a transition from Anderson localization to quantum chaos.
Finally, we explore the physics of dimerized quantum magnets by engineering exchange couplings along the ladder. We map out the quantum phase transition as a function of dimerization strength by locally measuring the magnetization and its variance, observing signatures consistent with Bose-Einstein condensation of triplon excitations.
Together, these experiments establish the Ge/SiGe quantum dot platform as a powerful tool for exploring quantum magnetism and strongly correlated phenomena with unprecedented control, advancing our ability to study artificial quantum matter in scalable solid-state platforms.
References:
[1] T. Hensgens et al., Nature 548, 70-73 (2017).
[2] P. Cova-Fariña et al., arXiv:2506.08663
Gate-defined semiconductor quantum dot arrays are a promising platform for digital and analog quantum simulations due to their scalability and precise control capabilities [1].
I will present our recent progress in using a Ge/SiGe 2x4 quantum dot ladder as a platform for quantum simulation of spin physics, where exquisite control over individual spin qubits and their couplings enables us to engineer and probe many-body phenomena in a highly controllable solid-state setting.
I'll discuss three main experimental results: First, we demonstrate quantum walks of magnon (single-spin) and triplon (two-spin) excitations propagating through the array [2]. By dynamically tuning exchange interactions, we show how we can prepare these excitations on demand and control their propagation characteristics.
Second, we develop a many-body spectroscopy tool based on Ramsey interferometry and reconstruct the energy spectrum of spin chains with up to 8 spins. By adiabatic ramping, we achieve a one-to-one mapping from computational (Zeeman) basis states to many-body eigenstates. Analysis of the energy level statistics reveals signatures of a transition from Anderson localization to quantum chaos.
Finally, we explore the physics of dimerized quantum magnets by engineering exchange couplings along the ladder. We map out the quantum phase transition as a function of dimerization strength by locally measuring the magnetization and its variance, observing signatures consistent with Bose-Einstein condensation of triplon excitations.
Together, these experiments establish the Ge/SiGe quantum dot platform as a powerful tool for exploring quantum magnetism and strongly correlated phenomena with unprecedented control, advancing our ability to study artificial quantum matter in scalable solid-state platforms.
References:
[1] T. Hensgens et al., Nature 548, 70-73 (2017).
[2] P. Cova-Fariña et al., arXiv:2506.08663