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Digital-analog simulations of Schrödinger cat states in the Dicke-Ising model

Dmitriy S. Shapiro1,*, Yannik Weber2, Tim Bode1, Frank K. Wilhelm1,2, and Dmitry Bagrets1,3

  • *Contact author: d.shapiro@fz-juelich.de
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Phys. Rev. A 112, 042412 – Published 6 October, 2025

DOI: https://doi.org/10.1103/wbp6-y3vd

Abstract

The Dicke-Ising model, one of the few paradigmatic models of matter-light interaction, exhibits a superradiant quantum phase transition above a critical coupling strength. However, in natural optical systems, its experimental validation is hindered by a “no-go theorem.” Here, we propose a digital-analog quantum simulator for this model based on an ensemble of interacting qubits coupled to a single-mode photonic resonator. We analyze the system's free-energy landscape using field-theoretical methods and develop a digital-analog quantum algorithm that disentangles qubit and photon degrees of freedom through a parity-measurement protocol. This disentangling enables the emulation of a photonic Schrödinger cat state, which is a hallmark of the superradiant ground state in finite-size systems and can be unambiguously probed through the Wigner tomography of the resonator's field.

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Phys. Rev. A 112, 042412– Published 6 October, 2025
  • Received 19 December 2024
  • Revised 29 July 2025
  • Accepted 16 September 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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