Simulating open quantum systems with giant atoms

Open quantum many-body systems are of both fundamental and applicational interest. However, it remains an open challenge to simulate and solve such systems, both with state-of-the-art classical methods and with quantum-simulation protocols. In this talk, we introduce a versatile platform for quantum simulation of open systems: giant atoms, i.e., atoms (possibly artificial), that couple to a waveguide at multiple points, which can be wavelengths apart. We first show that a single giant atom can be used to simulate the dynamics of a driven dissipative qubit; various parameter regimes can be simulated by simply properly tuning the frequency of the giant atom. This example highlights the tunability of giant atoms, their versatility for performing post-selection, and their stability against realistic imperfections. We further show that two giant atoms can simulate the dynamics of a protected qubit coupled to a dissipative qubit. This demonstration highlights the connectivity of giant atoms mediated by the waveguide, which allows two-qubit gates to be performed without additional couplers between qubits - a unique property of giant atoms, which has been demonstrated with superconducting qubits. The tunability and connectivity of giant atoms enables the generalization of our protocol to larger system sizes, allowing to perform quantum simulation on open quantum many-body systems (in particular, dissipative spin systems). We discuss the challenges that may arise when scaling up our quantum-simulation protocol in this way.