Probing Entanglement and Symmetries in Random States Using a Superconducting Quantum Processor

Quantum many-body systems display an extraordinary degree of complexity, yet many of their features are universal: they depend not on microscopic details, but on a few fundamental physical aspects such as symmetries. A central challenge is to distill these universal characteristics from model-specific ones. Random quantum states sampled from a uniform distribution, the Haar measure, provide a powerful framework for capturing this typicality. Here, we experimentally study the entanglement and symmetries of random many-body quantum states generated by evolving simple product states under ergodic Floquet models. We find excellent agreement with the predictions from the Haar-random state ensemble. First, we measure the Rényi-2 entanglement entropy as a function of the subsystem size, observing the Page curve. Second, we probe the subsystem symmetries using entanglement asymmetry. Finally, we measure the moments of partially transposed reduced density matrices obtained by tracing out part of the system in the generated ensembles, thereby revealing distinct entanglement phases. Our results offer an experimental perspective on the typical entanglement and symmetries of many-body quantum systems.

💡 Research Summary

This work presents a comprehensive experimental study of the entanglement structure and symmetry properties of random many‑body quantum states generated on a superconducting quantum processor. The authors employ a low‑depth Floquet circuit, V = e^{‑iH_yT/3}e^{‑iH_zT/3}e^{‑iH_xT/3}, repeatedly applied τ times to an initial product state |0⟩^{⊗L}. The Hamiltonians H_{x,y,z} consist of nearest‑neighbor XX couplings with random on‑site fields drawn uniformly from