arXiv subjects

Leo Radzihovsky

Publications and source records attributed to Leo Radzihovsky.

At least 19 recordsLinked to original sources

arXiv2025

Prospects for a Solid-State Nuclear Clock

Motivated by recent experimental breakthroughs toward a realization of a solid-state Thorium-229 nuclear clock, we review the technology, basic physics motivation, and limitations of the present generation of atomic clocks. We then discuss prospects for a new generation of clocks based on an anomalous low-energy 8.4 eV nuclear transition in Th-229, with an extremely long lifetime of 641 seconds when doped into CaF crystals. To realize such solid-state nuclear clocks one must confront basic nuclear, AMO, and solid state physics questions. Key challenges are understanding and minimizing the effects of inhomogeneous broadening, associated with strains and electric field gradients due to both the Th dopants and intrinsic crystal defects.

physics.atom-ph↗

arXiv2025

Field Theory of Borromean Super-counterfluids

We introduce a class of dynamical field theories for $N$-component "Borromean" ($N\geq 3$) super-counterfluid order, naturally formulated in terms of inter-species bosonic fields $\psi_{\alpha\beta}$. Their condensation breaks the normal-state [U(1)]$^N$ symmetry down to its diagonal U(1) subgroup, thereby encoding the arrest of the net superflow. This approach broadens our understanding of dynamical properties of super-counterfluids, at low energies capturing its universal properties, phase transition, counterflow vortices, and many of its other properties. Such super-counterfluid strikingly exhibits $N$ distinct flavors of energetically stable elementary vortex solutions, despite $\mathbb{Z}^{N-1}$ homotopy group of its $N\! -\! 1$ independent Goldstone modes, with $N\! -\! 1$ topologically distinct elementary vortex types, obeying modular arithmetic. The model leads to Borromean hydrodynamics as a low-energy theory, reveals counteflow AC Josephson effect, and generically predicts a first-order character of the phase transitions into Borromean super-counterfluid state in dimensions greater than two.

cond-mat.quant-gas↗

arXiv2025

Emergent Berezinskii-Kosterlitz-Thouless deconfinement in super-Coulombic plasmas

We study the statistical mechanics of two-dimensional "super-Coulombic" plasmas, namely, neutral plasmas with power-law interactions longer-ranged than Coulomb. To that end, we employ numerically exact large-scale Monte Carlo simulations. Contrary to naive energy-entropy arguments, we observe a charge confinement-deconfinement transition as a function of temperature. Remarkably, the transition lies in the Berezinskii-Kosterlitz-Thouless (BKT) universality class. Our results corroborate recent dielectric medium and renormalization group calculations predicting effective long-scale Coulomb interactions in microscopically super-Coulombic gases. We explicitly showcase this novel dielectric screening phenomenon, capturing the emergent Coulomb potential and the associated crossover length scale. This is achieved by utilizing a new test charge based methodology for determining effective inter-particle interactions. Lastly, we show that this Coulomb emergence and the associated BKT transition occur universally across generic interactions and densities.

cond-mat.stat-mech↗

arXiv2024

An active hydroelastic liquid crystal phase of a fluttering ferroelectric nematic

Polarization flutter, produced by an applied AC electric field drives an equilibrium ferroelectric nematic ($\mathrm{N_F}$) liquid crystal (LC) through a transition into a dissipative active ferroelectric nematic state exhibiting strong elasto-hydrodynamic intermolecular interaction. In such a fluttering ferroelectric, the typical equilibrium $\mathrm{N_F}$ textural features adopted to reduce electrostatic energy, such as preferences for director bend, and alignment of polarization parallel to LC/air interfaces, are overcome, giving way to nonequilibrium conjugate structures in which director splay, and alignment of polarization normal to $\mathrm{N_F}$/air interfaces are preferred. Viewing the latter textures as those of an active nematic phase reveals that self-organization to reduce effective viscosity and resulting dissipation generates a flow-driven apparent nematic elasticity and interface structuring that dominates equilibrium LC elastic and surface forces.

cond-mat.soft↗

arXiv2024

Quantum phases and transitions of bosons on a comb lattice

Motivated to elucidate the nature of quantum phases and their criticality when entangled with a correlated quantum bath, we study interacting bosons on a "comb lattice" -- a one-dimensional backbone (system) coupled at its sites to otherwise independent one-dimensional "teeth" chains (bath). We map out the corresponding phase diagram, detailing the nature of the phases and phase transitions. Controlled by the backbone and teeth hopping amplitudes, on-site interaction and chemical potential, phases include a Mott-insulator (MI), backbone (LLb) and teeth (LLp) Luttinger liquids, and the long-range ordered incoherent superfluid (iSF). We explore their properties and potential realizations in condensed matter and cold-atom experiments and simulations.

cond-mat.quant-gas↗

arXiv2024

Coulomb universality

Motivated by a number of realizations of long-range interacting systems, including ultra-cold atomic and molecular gases, we study a neutral plasma with power-law interactions longer-ranged than Coulombic. We find that beyond a crossover length, such interactions are universally screened down to a standard Coulomb form in all spatial dimensions. This implies, counter-intuitively, that in two dimensions and below, such a "super-Coulombic" gas is asymptotically Coulombically confining at low temperatures. At higher temperatures, the plasma undergoes a deconfining transition that in two dimensions is the same Kosterlitz-Thouless transition that occurs in a conventional Coulomb gas, but at an elevated temperature that we calculate. We also predict that in contrast, above two dimensions, even when naively the bare potential is confining, there is no confined phase of the plasma at any nonzero temperature. In addition, the super-Coulomb to Coulomb crossover is followed at longer length scales by an unconventional "Debye-Huckel" screening, which leads to faster-than-Coulombic, power-law decay of the screened potential, in contrast to the usual exponentially decaying Yukawa potential. Furthermore, we show that power-law potentials, that fall off more rapidly than Coulomb, are screened down to a shorter-ranged power-law, rather than an exponential Debye-Huckel Yukawa form. We expect these prediction to be testable in simulations, and hope they will inspire experimental studies in various platforms.

cond-mat.stat-mech↗

arXiv2023

Reentrant supersolidity

A "supersolid" -- a crystal that exhibits an off-diagonal long-range order and a superflow -- has been a subject of much research since its first proposal [Andreev and Lifshitz 1969], but has not been realized as a ground state of short-range interacting bosons in a continuum. In this note I point out a simple and generic mechanism for a thermally-driven reentrant supersolidity, and discuss challenges of experimental realization of this idea. In the limit of bosons in a periodic potential, this mechanism reduces to a {\em reentrant} low-temperature normal-superfluid transition, that should be accessible to simulations and in current experiments on bosonic atoms in an optical periodic potential.

cond-mat.quant-gas↗

arXiv2023

"Tattered" membrane

Ideal crystalline membranes, realized by graphene and other atomic monolayers, exhibit rich physics - a universal anomalous elasticity of the critical "flat" phase characterized by a negative Poisson ratio, universally singular elastic moduli, order-from-disorder and a crumpling transition. We formulate a generalized $D$-dimensional field theory, parameterized by an $O(d)\times O(D)$ tensor field with an {\it energetic} longitudinal constraint. For a soft constraint the resulting field theory describes a new class of a fluctuating "tattered" membranes, exhibiting a nonzero density of topological connectivity defects - slits, cracks and faults at an effective medium level. For hard, infinite-coupling constraint, the model reproduces the conventional crystalline membrane and its crumpling transition, and thereby demonstrates the essence of the difference between an elastic membrane and conventional field theories. Two additional fixed points emerge within the critical manifold, (i) globally attractive, "isotropic" $O(d)\times O(D)$, and (ii) "transverse", which in $D=2$ is the exact "dual" of the elastic membrane. Their properties are obtained in general $D,d$ from the renormalization group and the self-consistent screening analyses.

cond-mat.stat-mech↗

arXiv2023

Universal Correlations as Fingerprints of Transverse Quantum Fluids

We study universal off-diagonal correlations in transverse quantum fluids (TQF) -- a new class of quasi-one-dimensional superfluids featuring long-range-ordered ground states. These exhibit unique self-similar space-time relations scaling with $x^2/D\tau$ that serve as fingerprints of the specific states. The results obtained with the effective field theory are found to be in perfect agreement with {\it ab initio} simulations of hard-core bosons on a lattice -- a simple microscopic realization of TQF. This allows an accurate determination -- at nonzero temperature and finite system size -- of such key ground-state properties as the condensate and superfluid densities, and characteristic parameter $D$.

cond-mat.other↗

arXiv2023

Quantum vortex lattice: Lifshitz duality, topological defects and multipole symmetries

We study an effective field theory of a vortex lattice in a two-dimensional neutral rotating superfluid. Utilizing particle-vortex dualities, we explore its formulation in terms of a $U(1)$ gauge theory coupled to elasticity, that at low energies reduces to a compact Lifshitz theory augmented with a Berry phase term encoding the vortex dynamics in the presence of a superflow. Utilizing elasticity- and Lifshitz-gauge theory dualities, we derive dual formulations of the vortex lattice in terms of a traceless symmetric scalar-charge theory and demonstrate low-energy equivalence of our dual gauge theory to its elasticity-gauge theory dual. We further discuss a multipole symmetry of the vortex lattice and its dual gauge theory's multipole one-form symmetries. We also study its topological crystalline defects, where the multipole one-form symmetry plays a prominent role. It classifies the defects, explains their restricted mobility, and characterizes descendant vortex phases, which includes a novel vortex supersolid phase. Using the dual gauge theory, we also develop a mean-field theory for the quantum melting transition from a vortex crystal to a vortex supersolid.

cond-mat.str-el↗

arXiv2023

$O(N)$ smectic $\sigma$-model

A unidirectional "density" wave order in an otherwise isotropic environment is guaranteed to display a smecticlike Goldstone mode. Examples of such "soft" states include conventional smectic liquid crystals, putative Fulde-Ferrell-Larkin-Ovchinnikov superfluids, and helical states of frustrated bosons and spins. Here we develop generalized spin-smectic $\sigma$-models that break $O(N)$ internal symmetry in addition to the $d$-dimensional rotational and uniaxial translational symmetries. We explore long-wavelength properties of such strongly fluctuating states, show that they are characterized by a "double-power-law" static structure peak, and analyze their asymptotic symmetry-reduced crossover to conventional low-energy modes. We also present the associated Ginzburg-Landau theory, describing phase transition into such spin-smectic states, and discuss experimental realization of such models.

cond-mat.stat-mech↗

arXiv2023

Transverse Quantum Fluids

Motivated by remarkable properties of superfluid edge dislocations in solid Helium-4, we discuss a broad class of quantum systems -- boundaries in phase separated lattice states, magnetic domain walls, and ensembles of Luttinger liquids -- that can be classified as Transverse Quantum Fluids (TQF). After introducing the general idea of TQF, we focus on a coupled array of Luttinger liquids forming an incoherent TQF. This state is a long-range ordered quasi-one-dimensional superfluid, topologically protected against quantum phase slips by tight-binding of instanton dipoles, that has no coherent quasi-particle excitations at low energies. Incoherent TQF is a striking example of the irrelevance of the Landau quasiparticle criterion for superfluidity in systems that lack Galilean invariance. We detail its phenomenology, to motivate a number of experimental studies in condensed matter and cold atomic systems.

cond-mat.other↗

arXiv2023

Critical Matter

As part of a chapter for a book titled "50 years of the renormalization group", dedicated to the memory of Michael E. Fisher, edited by Amnon Aharony, Ora Entin-Wohlman, David Huse, and Leo Radzihovsky, I review a class of novel ordered states of "critical matter", that exhibit strongly fluctuating universal power-law orders, controlled by an infra-red attractive, non-Gaussian fixed point. I will illustrate how RG methods pioneered by Wilson and Fisher can be used to deduce critical phenomenology of such critical phases, resembling that of a critical point of second order phase transitions, but requiring no fine tuning.

cond-mat.stat-mech↗

arXiv2023

Superfluid Edge Dislocation: Transverse Quantum Fluid

Recently, it has been argued by Kuklov et al., that unusual features associated with the superflow-through-solid effect observed in solid He4 can be explained by unique properties of dilute distribution of superfluid edge dislocations. We demonstrate that stability of supercurrents controlled by quantum phase slips (instantons), and other exotic infrared properties of the superfluid dislocations readily follow from a one-dimensional quantum liquid distinguished by an effectively infinite compressibility (in the absence of Peierls potential) associated with the edge dislocation's ability to climb. This establishes a new class of quasi-one-dimensional superfluid states that remain stable and long-range ordered despite their low dimensionality. We propose an experiment to test our mass-current--pressure characteristic prediction.

cond-mat.other↗

arXiv2022

Fracton Matter

We review a burgeoning field of "fractons" -- a class of models where quasi-particles are strictly immobile or display restricted mobility that can be understood through generalized multipolar symmetries and associated conservation laws. Focusing on just a corner of this fast-growing subject, we will demonstrate how one class of such theories -- symmetric tensor and coupled-vector gauge theories surprisingly emerge from familiar elasticity of a two-dimensional quantum crystal. The disclination and dislocation crystal defects respectively map onto charges and dipoles of the fracton gauge theory. This fracton-elasticity duality leads to predictions of fractonic phases and quantum phase transitions to their descendants, that are duals of the commensurate crystal, supersolid, smectic, hexatic liquid crystals, as well as amorphous solids, quasi-crystals and elastic membranes. We show how these dual gauge theories provide a field theoretic description of quantum melting transitions through a generalized Higgs mechanism. We demonstrate how they can be equivalently constructed as gauged models with global multipole symmetries. We expect extensions of such gauge-elasticity dualities to generalized elasticity theories provide a route to discovery of new fractonic models and their potential experimental realizations.

cond-mat.str-el↗

arXiv2022

Fractonic gauge theory of smectics

Motivated by striped correlated quantum matter, and the recently developed duality between elasticity of a two-dimensional (2D) crystal and a gauge theory, we derive a dual coupled U(1) vector gauge theory for a two-dimensional (2D) quantum smectic, where the disclination is mapped onto the fractonic charge, that we demonstrate can only move transversely to smectic layers. This smectic gauge theory dual also emerges from a gauge dual of a quantum crystal after a Higgs transition corresponding to a single flavor of its dipole condensation, an anisotropic quantum melting via dislocation proliferation. A condensation of the second flavor of dislocations is described by another Higgs transition describing the smectic-to-nematic melting. We also utilize the electrostatic limit of this duality to formulate a melting of a 2D classical smectic in terms of a higher derivative sine- Gordon model, demonstrating its instability to a nematic at any nonzero temperature. Generalizing this classical duality to a 3D smectic, gives formulation of a 3D nematic-to-smectic transition in terms of an anisotropic Abelian-Higgs model.

cond-mat.str-el↗

arXiv2022

Lifshitz gauge duality

Motivated by a variety of realizations of the compact Lifshitz model I derive its fractonic gauge dual. The resulting U(1) vector gauge theory efficiently and robustly encodes the restricted mobility of its dipole conserving charged matter and the corresponding topological vortex defects. The gauge theory provides a transparent formulation of the three phases of the Lifshitz model and gives a field theoretic formulation of the associated two-stage Higgs transitions.

cond-mat.str-el↗

arXiv2022

Helical superfluid in a frustrated honeycomb Bose-Hubbard model

We study a "helical" superfluid, a nonzero-momentum condensate in a frustrated bosonic model. At mean-field Bogoliubov level, such a novel state exhibits "smectic" fluctuation that are qualitatively stronger than that of a conventional superfluid. We develop a phase diagram and compute a variety of its physical properties, including the spectrum, structure factor, condensate depletion, momentum distribution, all of which are qualitatively distinct from that of a conventional superfluid. Interplay of fluctuations, interaction and lattice effects gives rise to the phenomenon of order-by-disorder, leading to a crossover from the smectic superfluid regime to the anisotropic XY superfluid phase. We complement the microscopic lattice analysis with a field theoretic description for such a helical superfluid, which we derive from microscopics and justify on general symmetry grounds, reassuringly finding full consistency. Possible experimental realizations are discussed.

cond-mat.quant-gas↗