We study the zero-temperature phase diagram of two-dimensional helium-4 using neural quantum states. Our variational description allows us to address liquid and solid phases using the same functional form as well as exploring possible melting scenarios—for instance, via an intermediate hexatic phase. Notably, this is achieved by performing fixed pressure variational Monte Carlo calculations. Within the isobaric ensemble framework, we are able to clearly identify the first-order liquid-solid phase transition. We additionally compute the Rényi-2 entanglement entropy across the liquid-solid phase transition and find a sharp decrease upon freezing. Calculations for larger systems follow the metastable liquid and solid branches in the transient region, while signatures of a hexatic order coexisting with a small condensate fraction are observed only for smaller systems as a finite-size effect.

Close

PrevNext

View figure in article

• Entanglement entropy
• First order phase transitions
• Liquid-solid phase transition
• Helium-4 superfluids
• Liquid crystals
• Supersolids
• Neural network simulations
• Quantum Monte Carlo