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Anatoly Kuklov

Publications and source records attributed to Anatoly Kuklov.

At least 37 records · Page 2Linked to original sources
arXiv2018

Revisiting universality of the liquid-gas critical point in 2D

Critical point of liquid-gas (LG) transition does not conform with the paradigm of spontaneous symmetry breaking because there is no broken symmetry in both phases. This stimulated the ongoing debate about the nature of the universality class of the transition -- lasting since the creation of the theory of scaling. We revisit the conjecture that the LG criticality is that of the Ising model. Large scale Monte Carlo simulations of the LG criticality in 2D free space in combination with the numerical flowgram method give the critical indices agreeing with the Onsager values within the error of 1\%. The related problem about the role of higher order odd terms in the (real) $φ^4$ field model is addressed too. The scaling dimension of the $φ^5$ term at criticality is shown to be the same as of the linear one $φ$. We suggest that the role of all higher order odd terms is simply in generating the linear field operator at the criticality.

cond-mat.stat-mech↗
arXiv2018

Phases of superclimbing dislocation with long-range interaction between jogs

The main candidate for the superfluid pathways in solid Helium-4 are dislocations with Burgers vector along the hcp symmetry axis. Here we focus on quantum behavior of a generic edge dislocation which can perform superclimb -- climb supported by the superflow along its core. The role of the long range elastic interactions between jogs is addressed by Monte Carlo simulations. It is found that such interactions do not change qualitatively the phase diagram found without accounting for such forces. Their main effect consists of renormalizing the effective scale determining compressibility of the dislocation in the Tomonaga-Luttinger Liquid phase. It is also found that the quantum rough phase of the dislocation can be well described within the gaussian approximation which features off-diagonal long range order in 1D for the superfluid order parameter along the core.

cond-mat.other↗
arXiv2016

Emergence of Luttinger Liquid behavior of a superclimbing dislocation

A superclimbing dislocation spread over several valleys of Peierls potential in solid Helium-4 represents a non-Luttinger Liquid according to the elementary scaling dimensional analysis because its excitation spectrum is parabolic. Monte Carlo simulations, however, reveal that such a dislocation develops Luttinger Liquid behavior, which can also undergo a transition into insulating state. External bias can restore the parabolic spectrum. An experimental verification of the effect is proposed.

cond-mat.other↗
arXiv2016

Sliding phases in U(1) symmetric systems -- mirage of the renormalization group

We analyse the proposal of sliding phases (SP) in layers hosting global U(1) symmetric variables with finite inter-layer Josephson coupling. Based on the Kosterlitz-Thouless renormalization group (RG) approach, such phases were predicted to exist in various layered (or 1D quantum coupled) systems. The key in the RG argument is treating the coupling as though the variables are non-compact. Large scale Monte Carlo simulations of a layered model, where the SP is supposed to exist, finds no indication of such a phase. Instead, 3D behavior is observed. This result is consistent with the asymptotically exact analytical solution. A generic argument against SP in translationally invariant systems with short range interactions is provided. We have also suggested an alternative model for the SP -- adding long-range interactions to the inter-layer Josephson term.

cond-mat.stat-mech↗
arXiv2016

Quasi-molecular bosonic complexes -- a pathway to atomic analog of SQUID with controlled sensitivity

Recent experimental advances in realizing degenerate quantum dipolar gases in optical lattices and the flexibility of experimental setups in attaining various geometries offer the opportunity to explore exotic quantum many-body phases stabilized by anisotropic, long-range dipolar interaction. Moreover, the unprecedented control over the various physical properties of these systems, ranging from the quantum statistics of the particles, to the inter-particle interactions, allow one to engineer novel devices. In this paper, we consider dipolar bosons trapped in a stack of one-dimensional optical lattice layers, previously studied in [1]. Building on our prior results, we provide a description of the quantum phases stabilized in this system which include composite superfluids, solids, and supercounterfluids, most of which are found to be threshold- less with respect to the dipolar interaction strength. We also demonstrate the effect of enhanced sensitivity to rotations of a SQUID-type device made of two composite superfluids trapped in a ring-shaped optical lattice layer with weak links.

cond-mat.quant-gas↗
arXiv2015

Giant isochoric compressibility of solid Helium-4: the bistability of superlcimbing dislocations

A significant accumulation of matter in solid Helium-4 observed during the superflow events, dubbed as the giant isochoric compressibility (or the syringe effect), is discussed within the model of dislocations with superfluid core. It is shown that solid Helium-4 in a contact with superfluid reservoir can develop a bistability with respect to the syringe fraction, with the threshold for the bias by chemical potential determined by a typical free length of dislocations with superfluid core. The main implications of this effect are: hysteresis and strongly non-linear dynamical behavior leading to growth, proliferation and possibly exiting from a crystal of superclimbing dislocations. Three major channels for such dynamics are identified: i) injection and inflation of the prismatic loops from the boundary; ii) Bardeed-Herring generation of the loops in the bulk; iii) helical instability of the screw dislocations. It is argued that the current experiments are likely to be well in this regime. Several testable predictions for the time and the bias dependencies of the dynamics are suggested

cond-mat.other↗
arXiv2014

Quantum Plasticity and Supersolid Response in Helium-4

We argue that the three key phenomena recently observed in solid $^4$He---mass supertransport, anomalous isochoric compressibility (syringe effect), and giant plasticity---are closely linked to each other through the physics of an interconnected network of tilted quantum-rough dislocations. As immediate implications of this connection several predictions follow: In the absence of $^3$He impurities, the syringe effect and giant plasticity persist down to $T=0$; the dynamical low-frequency syringe and giant-plasticity responses are dispersionless; and similarly to giant plasticity but without direct relationship to the supertransport along the dislocation cores, $^3$He impurities should suppress the syringe effect partially or completely at appropriately low temperatures.

cond-mat.other↗
arXiv2014

Topological quantum phases of ${^4}$He confined to nanoporous materials

The ground state of $^4$He confined in a system with the topology of a cylinder can display properties of a solid, superfluid and liquid crystal. This phase, which we call compactified supersolid (CSS), originates from wrapping the basal planes of the bulk hcp solid into concentric cylindrical shells, with several central shells exhibiting superfluidity along the axial direction. Its main feature is the presence of a topological defect which can be viewed as a disclination with Frank index $n=1$ observed in liquid crystals, and which, in addition, has a superfluid core. The CSS as well as its transition to an insulating compactified solid with a very wide hysteresis loop are found by ab initio Monte Carlo simulations. A simple analytical model captures qualitatively correctly the main property of the CSS -- a gradual decrease of the superfluid response with increasing pressure.

cond-mat.other↗
arXiv2012

Interplay of non-linear elasticity and dislocation-induced superfluidity in solid Helium-4

The mechanism of the roughening induced partial depinning of gliding dislocations from Helium-3 impurities is proposed as an alternative to the standard "boiling off". We give a strong argument that Helium-3 remains bound to dislocations even at large temperatures due to very long equilibration times. A scenario leading to the similarity between elastic and superfluid responses of solid Helium-4 is also discussed. Its main ingredient is a strong suppression of the superfluidity along dislocation cores by dislocation kinks (D. Aleinikava, et. al., arXiv:0812.0983). These kinks, on one hand, determine the temperature and Helium-3 dependencies of the generalized shear modulus and, on the other hand, control the superfluid response. Several proposals for theoretical and experimental studies of solid Helium-4 are suggested.

cond-mat.other↗
arXiv2012

Quantum phase transitions to superfluid state of chains in a polarized gas of dipolar molecules

We analyze the nature of quantum phase transition to a superfluid state of flexible chains in a gas of polar bosonic molecules confined in a stack of $N$ identical 1d ("cigar" type) optical lattice layers and polarized perpendicularly to the layers. Monte Carlo simulations within the $J$-current model show that, in the absence of the inter-tube tunneling, the transition to the $N$-layered superfluid is in the Berezinskii-Kosterlitz-Thouless universality class in the one-particle density matrix channel. The inter-layer tunneling changes it to the $q=N$ 2d Potts universality. The low energy field descriptions of the transition are discussed in terms of conformal field theories.

cond-mat.quant-gas↗
arXiv2011

The role of Helium-3 impurities in the stress induced roughening of superclimbing dislocations in solid Helium-4

We analyze the stress induced and thermally assisted roughening of a forest of superclimbing dislocations in a Peierls potential in the presence of Helium-3 impurities and randomly frozen in static stresses. It is shown that the temperature of the dip $T_d$ in the flow rate observed by Ray and Hallock (Phys.Rev. Lett. {\bf 105}, 145301 (2010)) is determined by the energy of the impurity activation from dislocation core. However, it is suppressed by, essentially, the logarithm of the impurity fraction. The width of the dip is determined by inhomogeneous fluctuations of the stresses and is shown to be much smaller than $T_d$.

cond-mat.other↗
arXiv2011

Stress induced dislocation roughening -- phase transition in 1d at finite temperature

We present an example of a generically forbidden phase transition in 1d at finite temperature -- stress induced and thermally assisted roughening of a superclimbing dislocation in a Peierls potential. We also argue that such roughening is behind the strong suppression of the superflow through solid \he4 in a narrow temperature range recently observed by Ray and Hallock (Phys.Rev. Lett. {\bf 105}, 145301 (2010)).

cond-mat.other↗
arXiv2011

Superfluidity of flexible chains of polar molecules

We study properties of quantum chains in a gas of polar bosonic molecules confined in a stack of N identical one- and two- dimensional optical lattice layers, with molecular dipole moments aligned perpendicularly to the layers. Quantum Monte Carlo simulations of a single chain (formed by a single molecule on each layer) reveal its quantum roughening transition. The case of finite in-layer density of molecules is studied within the framework of the J-current model approximation, and it is found that N-independent molecular superfluid phase can undergo a quantum phase transition to a rough chain superfluid. A theorem is proven that no superfluidity of chains with length shorter than N is possible. The scheme for detecting chain formation is proposed.

cond-mat.other↗
arXiv2006

Detecting multi-atomic composite states in optical lattices

We propose and discuss methods for detecting quasi-molecular complexes which are expected to form in strongly interacting optical lattice systems. Particular emphasis is placed on the detection of composite fermions forming in Bose-Fermi mixtures. We argue that, as an indirect indication of the composite fermions and a generic consequence of strong interactions, periodic correlations must appear in the atom shot noise of bosonic absorption images, similar to the bosonic Mott insulator [S. Fölling, et al., Nature {\bf 434}, 481 (2005)]. The composites can also be detected directly and their quasi-momentum distribution measured. This method -- an extension of the technique of noise correlation interferometry [E. Altman et al., Phys. Rev. A {\bf 79}, 013603 (2004)] -- relies on measuring higher order correlations between the bosonic and fermionic shot noise in the absorption images. However, it fails for complexes consisting of more than three atoms.

cond-mat.other↗
arXiv2006

The fate of vacancy-induced supersolidity in 4He

The supersolid state of matter, exhibiting non-dissipative flow in solids, has been elusive for thirty five years. The recent discovery of a non-classical moment of inertia in solid 4He by Kim and Chan provided the first experimental evidence, although the interpretation in terms of supersolidity of the ideal crystal phase remains subject to debate. Using quantum Monte Carlo methods we investigate the long-standing question of vacancy-induced superflow and find that vacancies in a 4He crystal phase separate instead of forming a supersolid. On the other hand, non-equilibrium vacancies relaxing on defects of poly-crystalline samples could provide an explanation for the experimental observations.

cond-mat.other↗
arXiv2006

Deconfined criticality, runaway flow in the two-component scalar electrodynamics and weak first-order superfluid-solid transitions

We perform a comparative Monte Carlo study of the easy-plane deconfined critical point (DCP) action and its short-range counterpart to reveal close similarities between the two models for intermediate and strong coupling regimes. For weak coupling, the structure of the phase diagram depends on the interaction range: while the short-range model features a tricritical point and a continuous U(1)xU(1) transition,the long-range DCP action is characterized by the runaway renormalization flow of coupling into a first (I) order phase transition. We develop a "numerical flowgram" method for high precision studies of the runaway effect, weakly I-order transitions, and polycritical points. We prove that the easy-plane DCP action is the field theory of a weakly I-order phase transition between the valence bond solid and the easy-plane antiferromagnet (or superfluid, in particle language) for any value of the weak coupling strength. Our analysis also solves the long standing problem of what is the ultimate fate of the runaway flow to strong coupling in the theory of scalar electrodynamics in three dimensions with U(1)xU(1) symmetry of quartic interactions

cond-mat.str-el↗
arXiv2005

Ginzburg-Landau-Wilson Aspect of Deconfined Criticality

Monte Carlo study of the deconfined critical action phase diagram reveals a region where spinon deconfinement occurs through a weak first-order phase transition, in agreement with Ginzburg-Landau theory. Wilson renormalization argument in combination with the absence of the data collapse even in the regime of weak interaction between the spinons casts a serious doubt on the possibility of the continuous deconfinement transition. We also argue that if a continuous deconfined criticality does exist on the phase diagram, its nature is analogous, in a certain precise sense, to that of the XY universality class.

cond-mat.stat-mech↗