Description
Quantum phase transitions (QPTs) are interesting physical phenomena that often emerge in systems which are difficult to simulate classically, such as many-body systems in the thermodynamic limit. Recent research has shown that the Quantum Rabi Model (QRM) can exhibit signatures of a superradiant QPT [1], despite comprising only one qubit and one bosonic mode, and can be studied using circuit-QED digital quantum simulation [2]. While realising this model directly can be experimentally challenging, involving extreme disparities between system frequencies [3], similar superradiant QPT behaviours have been studied without the same frequency disparities in a modified QRM that also incorporates dispersive coupling, but with additional driven-dissipative dynamics included for photon-number stabilisation [4].
Here, we propose and study an alternative dispersive QRM with an additional nonlinear stabilisation, that is suitable for digital quantum simulation of superradiant QPT behaviours with more accessible frequency regimes. We show that a coherent nonlinear interaction also prevents unbounded photon growth beyond the transition, stabilising system dynamics without the need for dissipation. We explore equilibrium and dynamical characteristics of this model in regimes compatible with standard digital quantum simulation paradigms. By eliminating the need to access disparate frequency scales within a single simulation, which otherwise gives rise to fundamental practical obstacles for real-world digital quantum simulations, our results provide a realistic way to study QPT behaviours in circuit QED digital quantum simulators.
[1] Hwang et al., PRL 115, 180404 (2015)
[2] Langford et al., Nat Comms 8, 1715 (2017)
[3] Cai et al., Nat Comms 12, 1126 (2021)
[4] Grimsmo et al., Phys. Rev. A 89, 033802 (2014)
| I am the presenting author | Yes |
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