Two liquid states of distinguishable helium-4: the existence of another non-superfluid frozen by heating
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arXiv
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| Format: | Preprint |
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2024
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| author | Tsujimoto, Momoko Kinugawa, Kenichi |
| author_facet | Tsujimoto, Momoko Kinugawa, Kenichi |
| contents | We show that there can exist two liquid states in distinguishable helium-4 ($^4$He) obeying Boltzmann statistics by path integral centroid molecular dynamics (CMD) simulations. This is an indication of quantum liquid polyamorphism induced by nuclear quantum effect. For 0.08-3.3 K and 1-500 bar, we extensively conducted the isothermal-isobaric CMD simulations to explore not only possible states and state diagram but the state characteristics. The distinguishable $^4$He below 25 bar does not freeze down to 0.1 K even though it includes no Bosonic exchange effect and therefore no Bose condensation. One liquid state, low quantum-dispersion liquid (LQDL), is nearly identical to normal liquid He-I of real $^4$He. The other is high quantum-dispersion liquid (HQDL) consisting of atoms with longer quantum wavelength. This is another non-superfluid existing below 0.5 K or the temperatures of LQDL. The HQDL is also a low-entropy and fragile liquid to exhibit, unlike conventional liquids, rather gas-like relaxation of velocity autocorrelation function, while there the atoms diffuse without noticeable contribution from quantum tunneling. The LQDL-HQDL transition is not a thermodynamic phase transition but a continuous crossover accompanied by the change of the expansion factor of quantum wavelength. Freezing of HQDL into the low quantum-dispersion amorphous solid occurs by heating from 0.2 to 0.3 K at 40-50 bar, while this $P$-$T$ condition coincides with the Kim-Chan normal-supersolid phase boundary of real $^4$He. The obtained state diagram was compared with that of the confined subnano-scale $^4$He systems where Bosonic correlation is considerably suppressed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_07716 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Two liquid states of distinguishable helium-4: the existence of another non-superfluid frozen by heating Tsujimoto, Momoko Kinugawa, Kenichi Chemical Physics Disordered Systems and Neural Networks Quantum Gases Statistical Mechanics We show that there can exist two liquid states in distinguishable helium-4 ($^4$He) obeying Boltzmann statistics by path integral centroid molecular dynamics (CMD) simulations. This is an indication of quantum liquid polyamorphism induced by nuclear quantum effect. For 0.08-3.3 K and 1-500 bar, we extensively conducted the isothermal-isobaric CMD simulations to explore not only possible states and state diagram but the state characteristics. The distinguishable $^4$He below 25 bar does not freeze down to 0.1 K even though it includes no Bosonic exchange effect and therefore no Bose condensation. One liquid state, low quantum-dispersion liquid (LQDL), is nearly identical to normal liquid He-I of real $^4$He. The other is high quantum-dispersion liquid (HQDL) consisting of atoms with longer quantum wavelength. This is another non-superfluid existing below 0.5 K or the temperatures of LQDL. The HQDL is also a low-entropy and fragile liquid to exhibit, unlike conventional liquids, rather gas-like relaxation of velocity autocorrelation function, while there the atoms diffuse without noticeable contribution from quantum tunneling. The LQDL-HQDL transition is not a thermodynamic phase transition but a continuous crossover accompanied by the change of the expansion factor of quantum wavelength. Freezing of HQDL into the low quantum-dispersion amorphous solid occurs by heating from 0.2 to 0.3 K at 40-50 bar, while this $P$-$T$ condition coincides with the Kim-Chan normal-supersolid phase boundary of real $^4$He. The obtained state diagram was compared with that of the confined subnano-scale $^4$He systems where Bosonic correlation is considerably suppressed. |
| title | Two liquid states of distinguishable helium-4: the existence of another non-superfluid frozen by heating |
| topic | Chemical Physics Disordered Systems and Neural Networks Quantum Gases Statistical Mechanics |
| url | https://arxiv.org/abs/2404.07716 |