Probing spontaneously symmetry-broken phases through noise correlation measurements with cold atoms

Spontaneously symmetry-broken (SSB) phases are locally ordered states of matter characterizing a large variety of physical systems. Because of their specific ordering, their presence is usually witnessed by means of local order parameters. Here, we propose an alternative approach based on statistical correlations of noise after the ballistic expansion of an atomic cloud [1,2]. We indeed demonstrate that probing such noise correlators allows one to discriminate among different SSB phases characterized by spin-charge separation. As a particular example, we test our prediction on a 1D extended Fermi-Hubbard model, where the competition between local and nonlocal couplings gives rise to three different SSB phases: a charge density wave, a bond-ordering wave, and an antiferromagnet. Our numerical analysis shows that this approach can accurately capture the presence of these different SSB phases, thus representing an alternative and powerful strategy to characterize strongly interacting quantum matter [3].

[1] E. Altman, E. Demler, M. D. Lukin, Probing many-body states of ultracold atoms via noise correlations, Phys. Rev. A 70, 013603 (2004).

[2] S. Fölling, F. Gerbier, A. Widera, O. Mandel, T. Gericke, I. Bloch, Spatial quantum noise interferometry in expanding ultracold atom clouds, Nature (London) 434, 481 (2005).

[3] Gallego-Lizarribar, K., Julià-Farré, S., Lewenstein, M., Weitenberg, C., Barbiero, L., Argüello-Luengo, J, Probing spontaneously symmetry-broken phases with spin-charge separation through noise correlation measurements. Physical Review Research, 6(4), L042048 (2024).