Quantum Field Simulator: Oscillating Spacetime and the Emergence of Supersolid Properties in a Driven Superfluid
ORAL · Invited
Abstract
Systems driven far from equilibrium can exhibit properties that are qualitatively different from those at equilibrium, including the emergence of novel phases of matter with distinct material characteristics. Here, I report on our recent results obtained with a quantum field simulation platform based on a quasi-two-dimensional quantum gas of potassium atoms. This platform enables a detailed investigation of emergent many-body dynamics when the microscopic interaction strength is modulated periodically in time.
The initial dynamics are well captured within a perturbative description and can be understood as particle production in a relativistic scalar field theory with an oscillating Friedmann–Lemaître–Robertson–Walker spacetime metric. Crucially, our platform allows us to access the nonperturbative regime. There, we observe a spontaneous breaking of the homogeneity and isotropy of the initial state, accompanied by the emergence of a periodic spatial modulation of the effective metric.
We show that this phenomenon can be interpreted as a drift towards an attractive nonlinear fixed point, which we analyze theoretically using multi-scale analysis. Owing to the high degree of control in our quantum field simulator, we can not only prepare the system at the theoretically predicted fixed point, but also implement local control of the order parameter, allowing us to probe the excitation spectrum and thereby characterize the emergent state of matter.
We find that the spontaneously formed crystalline structure supports both superfluid and lattice excitations, consistent with the behavior expected for a one-dimensional supersolid. Furthermore, by preparing and stabilizing a stripe phase, we are able to investigate in detail and confirm recent theoretical predictions of a superfluid smectic-A liquid-crystal phase. Our results demonstrate a new pathway for engineering quantum materials, leveraging the capabilities of quantum field simulators based on ultracold gases.
The initial dynamics are well captured within a perturbative description and can be understood as particle production in a relativistic scalar field theory with an oscillating Friedmann–Lemaître–Robertson–Walker spacetime metric. Crucially, our platform allows us to access the nonperturbative regime. There, we observe a spontaneous breaking of the homogeneity and isotropy of the initial state, accompanied by the emergence of a periodic spatial modulation of the effective metric.
We show that this phenomenon can be interpreted as a drift towards an attractive nonlinear fixed point, which we analyze theoretically using multi-scale analysis. Owing to the high degree of control in our quantum field simulator, we can not only prepare the system at the theoretically predicted fixed point, but also implement local control of the order parameter, allowing us to probe the excitation spectrum and thereby characterize the emergent state of matter.
We find that the spontaneously formed crystalline structure supports both superfluid and lattice excitations, consistent with the behavior expected for a one-dimensional supersolid. Furthermore, by preparing and stabilizing a stripe phase, we are able to investigate in detail and confirm recent theoretical predictions of a superfluid smectic-A liquid-crystal phase. Our results demonstrate a new pathway for engineering quantum materials, leveraging the capabilities of quantum field simulators based on ultracold gases.
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Publication: Supersolid-like sound modes in a driven quantum gas. Nat. Phys. 21, 1064–1070 (2025). https://doi.org/10.1038/s41567-025-02927-4
Observation of Pattern Stabilization in a Driven Superfluid. PRX 15, 011026 (2025). https://doi.org/10.1103/PhysRevX.15.011026
Stable-fixed-point description of square-pattern formation in driven two-dimensional Bose-Einstein condensates. PRA 109, L051301 (2024). https://doi.org/10.1103/PhysRevA.109.L051301
Presenters
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Markus Oberthaler
- Kirchhoff-Institute for Physics