Entropy and disorder in quantum optics

F. T. Arecchi

Sergiy Skrebtsov, Gennady Khalimov, Volodymyr Oleksiyovych Chyshkala

We present the first theoretical study of CsPbBr3 perovskite nanocrystal (QD)-based optical Physical Unclonable Functions (PUFs) for post-quantum cryptographic applications. Unlike previous optical PUF platforms, CsPbBr3 PUFs exploit two independent entropy sources: (1) inherent size disorder of colloidal QD synthesis (dominant) and (2) ionic mismatch of B-site dopants (Mn2+, Yb3+, Bi3+) substituting Pb2+. We derive an analytical entropy model H(c,T)

Yufeng Song, Youjin Deng, Yuan-Yao He

Abstract The celebrated antiferromagnetic (AFM) phase transition was realized in a most recent optical lattice experiment for the 3D fermionic Hubbard model [ Shao et al . Nature 632 267 (2024) ]. Despite this important progress, it was observed that the AFM structure factor (and also the critical entropy) reaches its maximum at an interaction strength U / t ≃ 11.75, which is significantly larger than the theoretical prediction of U / t ≃ 8. Here, we resolve this discrepancy by studying the interplay between the thermal entropy, density disorder, and antiferromagnetism in the half-filled 3D Hubbard model, using numerically exact auxiliary-field quantum Monte Carlo simulations. We have achieved an accurate entropy phase diagram, enabling us to simulate arbitrary entropy path on the temperature-interaction plane and track experimental parameters effectively. We find that above the discrepancy can be quantitatively explained by the entropy increase associated with increasing interaction strength in experiments, and together with the lattice density disorder present in the experimental setup. We further investigate the entropy dependence of double occupancy and predict universal behaviors that could serve as valuable probes in future optical lattice experiments.

R. H. Graham

Jacob Park, Ehsan Khatami

The interplay of disorder and strong correlations in quantum many-body systems remains an open question. That is despite much progress made in recent years with ultracold atoms in optical lattices to better understand phenomena such as many-body localization or the effect of disorder on Mott metal-insulator transitions. Here, we utilize the numerical linked-cluster expansion technique, extended to treat disordered quantum lattice models, and study exact thermodynamic properties of the disordered Fermi-Hubbard model on the square and cubic geometries. We consider box distributions for the disorder in the onsite energy, the interaction strength, as well as the hopping amplitude and explore how energy, double occupancy, entropy, heat capacity, and magnetic correlations of the system in the thermodynamic limit evolve as the strength of disorder changes. We compare our findings with those obtained from determinant quantum Monte Carlo simulations and discuss the relevance of our results to experiments with cold fermionic atoms in optical lattices.

Peter W. Milonni