arXiv subjects

Anatoly B. Kuklov

Publications and source records attributed to Anatoly B. Kuklov.

4 recordsLinked to original sources

arXiv2025

Symmetry induced pairing in dark excitonic condensate at finite temperature

Bose Einstein condensate of dark intervalley excitons must be inherently multi-component because of crystalline symmetries. Since valleys hosting such excitons are separated by large quasi-momenta, a minimal inter-component Josephson-type coupling can only be established between pairs of excitons from the time-reversed valleys. As a result, a paired condensate can emerge at finite temperature, that is, the off-diagonal order exists for the pairs from the time-reversed valleys, while the individual valleys are disordered. This prediction follows from the elementary mean field analysis regardless of the dimensionality. However, as Monte Carlo simulations show, no such a phase exists in 3D crystals. Instead, the multi-component condensation proceeds as the Ist order transition from the normal state. The paired phase does exist in 2D for the number of the components $N_v\geq 6$. It forms by Berezinskii-Kosterlitz-Thouless transition from the high temperature (normal) phase. The multi-component condensate appears upon further lowering of temperature.

cond-mat.stat-mech↗

arXiv2022

Supertransport by Superclimbing Dislocations in $^4$He: When All Dimensions Matter

The unique superflow-through-solid effect observed in solid Helium-4 and attributed to the quasi-one-dimensional superfluidity along the dislocation cores exhibits two extraordinary features: (i) an exponentially strong suppression of the flow by a moderate increase in pressure, and (ii) an unusual temperature dependence of the flow rate with no analogy to any known system and in contradiction with the standard Luttinger liquid paradigm. Based on ab initio and model simulations, we argue that the two features are closely related: Thermal fluctuations of the shape of a superclimbing edge dislocation induce large, correlated, and asymmetric stress fields acting on the superfluid core. The critical flux is most sensitive to strong rare fluctuations and hereby acquires a sharp temperature dependence observed in experiments.

cond-mat.other↗

arXiv2019

Disorder-induced quantum properties of solid Helium-4

We briefly discuss theoretical and experimental discoveries in the field of supertransport and plasticity in imperfect solid \he4 and argue that these promise new exciting developments. Several experiments aimed at clarifying the origin of the supertransport and its relation to plasticity are proposed. In particular, we argue that "cold-working" protocols of sample preparation should be crucial in this respect.

cond-mat.soft↗

arXiv2019

Cooperative phase transitions in the system of photons and dye molecules

Bose condensed light can form new phases [1] in a dye filled cavity due to the presence of the orientational disorder created by dye molecules which are essentially frozen on the time scale of the photonic thermalization (few ps). At longer times (few ns) molecular degrees of freedom -- orientations and positions -- become important. Including them on equal footing with photons can change the nature of the photonic condensation -- it can proceed as Ist order phase transition which can also result in the mutual phase separation effect -- for photons and dye. The analysis is conducted within the mean field approach in the thermodynamic limit. Recommendations for the experimental detection of the transition nature are formulated.

cond-mat.quant-gas↗