Correlations and Coherence at Different Scales (CCDS25)

Entanglement entropy and its scaling properties have recently emerged as a way to classify states of matter. Measuring entanglement usually relies on full state tomography and requires exponentially large resources. To circumvent this complexity, a connection between entanglement entropy and fluctuations of conserved observables has been established and tested for systems and states exhibiting volume-law, area-law, and logarithmic scaling of entanglement [1]. Here we generalize this approach to non-conserved quantities and introduce reduced fluctuations, which can reveal the scaling properties of entanglement even when the symmetries of the system are broken [2]. We present this approach using numerical results for the spin-$1/2$ $XYZ$ model.

[1] K. Pöyhönen, A. G. Moghaddam, and T. Ojanen, Phys. Rev. Res. 4, 023200 (2022).
[2] S. Głodzik, A. G. Moghaddam, K. Pöyhönen, T. Ojanen, arXiv 2412.15765