Dresden 2026 – scientific programme
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AKPIK: Arbeitskreis Physik, moderne Informationstechnologie und Künstliche Intelligenz
AKPIK 5: Poster
AKPIK 5.15: Poster
Thursday, March 12, 2026, 15:00–16:30, P5
Digital-Analog Simulations of Schrödinger Cat states in the Dicke-Ising Model — •Dmitrii Shapiro1, Yannik Weber1, Tim Bode1, Frank K. Wilhelm1,2, and Dmitry Bagrets1,3 — 1Quantum Computing Analytics (PGI-12), Forschungszentrum Jülich, Germany — 2Saarland University, Germany — 3University of Cologne, Germany
We study the Dicke-Ising model: an Ising chain where all spins couple to a common bosonic mode. Due to competing spin-spin and spin-boson interactions, the phase diagram exhibits both second- and first-order superradiant quantum phase transitions (QPTs). At the QPT, the system evolves into an entangled superradiant state with a boson condensate. We discuss the free-energy landscape near the QPT, obtained by integrating out the spins. We then propose a digital-analog quantum simulator for the Dicke-Ising Hamiltonian based on interacting qubits coupled to a single-mode resonator. The many-body propagator is decomposed via Trotterization into layers of single- and two-qubit rotations alternating with Jaynes-Cummings (JC) gates that emulate spin-boson coupling. The JC gate is analog, as it exploits rotations in the resonator's native Hilbert space. We show that the superradiant state can be approximated by a quench protocol with a finite-depth circuit. Applying a selective measurement of global qubit parity yields a Schrödinger cat state in the photonic subspace---a hallmark of the superradiant ground state in finite-size systems. The cat state can be probed via Wigner tomography of the resonator field. For details, see [Shapiro et al., PRA 112, 042412 (2025)].
Keywords: superradiant transition; quantum simulation; Dicke–Ising model; cat states