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We present analytical results of the fundamental properties of the one-dimensional (1D) Hubbard model with a repulsive interaction. The new model results with arbitrary external fields include: (I) using the exact solutions of the Bethe ansatz equations of the Hubbard model, we first rigorously calculate the gapless spin and charge excitations, exhibiting exotic features of fractionalized spinons and holons. We then investigate the gapped excitations in terms of the spin string and the k − Λ string bound states at arbitrary driving fields, showing subtle differences in spin magnons and charge η -pair excitations. (II) For a high-density and high spin magnetization region, i.e. near the quadruple critical point, we further analytically obtain the thermodynamic properties, dimensionless ratios and scaling functions near quantum phase transitions. (III) Importantly, we give the general scaling functions at quantum criticality for arbitrary filling and interaction strength. These can directly apply to other integrable models. (IV) Based on the fractional excitations and the scaling laws, the spin-incoherent Luttinger liquid (SILL) with only the charge propagation mode is elucidated by the asymptotic of the two-point correlation functions with the help of conformal field theory. We also, for the first time, obtain the analytical results of the thermodynamics for the SILL. (V) Finally, to capture deeper insights into the Mott insulator and interaction-driven criticality, we further study the double occupancy and propose its associated contact and contact susceptibilities, through which an adiabatic cooling scheme based upon quantum criticality is proposed. In this scenario, we build up general relations among arbitrary external- and internal-potential-driven quantum phase transitions, providing a comprehensive understanding of quantum criticality. Our methods offer rich perspectives of quantum integrability and offer promising guidance for future experiments with interacting electrons and ultracold atoms, both with and without a lattice. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) systems have received a lot of attention due to their exotic physical phenomena such as quantization of conductance, Peierls instability, and Luttinger liquid behavior. Here, we present the synthesis of self-assembled quasi-1D bismuth (Bi) chains on an Au(111) substrate, highlighting their topological properties. Scanning tunneling microscopy and spectroscopy measurements reveal that the high-quality large area array is composed of Bi atomic chains with a bandgap of 0.5 eV. Density functional theory (DFT) calculations confirm the experimental observation and reveal the topological properties of the system, providing evidence of the spin texture of the Bi atomic chains. Our DFT results predict that a single Bi chain hosts exotic topological properties. The atomically precise synthesis of Bi atomic chains overcomes the limitation of the top-down approach toward integration of devices. The work sheds light on the realization of 1D system, providing a platform for further investigation into the intriguing physics in 1D systems. [ABSTRACT FROM AUTHOR]

Including the previously ignored dispersion of phonons we revisit the metal-insulator transition problem in one-dimensional electron-phonon systems on the basis of a modified spinless fermion Holstein model. Using matrix-product-state techniques we determine the global ground-state phase diagram in the thermodynamic limit for the half-filled band case, and show that in particular the curvature of the bare phonon band has a significant effect, not only on the transport properties characterized by the conductance and the Luttinger liquid parameter, but also on the phase space structure of the model as a whole. While a downward curved (convex) dispersion of the phonons only shifts the Tomonaga-Luttinger-liquid to charge-density-wave quantum phase transition towards stronger EP coupling, an upward curved (concave) phonon band leads to a new phase-separated state which, in the case of strong dispersion, can even completely cover the charge-density wave. Such phase separation does not occur in the related Edwards fermion-boson model. [ABSTRACT FROM AUTHOR]

1D structures/patterns (e.g., line defect arrays, 1D Moiré patterns) embedded in 2D materials provide fascinating platforms for exploring versatile intriguing phenomena, for example, 1D Luttinger liquids and charge density waves (CDWs). Despite persistent efforts, incorporating periodic 1D patterns into 2D materials remains an ongoing pursuit. Herein, the direct preparation of monolayer 1D‐defect‐induced Co4Te7 superlattices (with periodic Te defect lines in the upper Te layer in 1T‐CoTe2) is reported, on lattice‐matched SrTiO3(001) (STO(001)) substrates via molecular beam epitaxy (MBE). Utilizing on‐site scanning tunneling microscopy/spectroscopy (STM/STS) combined with density functional theory (DFT) calculations, the detailed atomic structure of monolayer Co4Te7 is identified, and its formation mechanisms from the synergistic effects of the Co/Te precursor ratio and adlayer‐substrate interfacial coupling are uncovered. The potential flat‐band feature of the monolayer Co4Te7 is also unveiled. This work should hereby offer valuable insights into the engineering of periodic 1D‐defect patterns in 2D materials, as well as the atomic‐scale structure and electronic property characterizations, thus paving ways for their intriguing property investigations. [ABSTRACT FROM AUTHOR]

The interplay between topology and interaction always plays an important role in condensed matter physics and induces many exotic quantum phases, while rare transition metal layered material (TMLM) has been proved to possess both. Here we report a TMLM Ta2Pd3Te5 has the two-dimensional second-order topology (also a quadrupole topological insulator) with correlated edge states - Luttinger liquid. It is ascribed to the unconventional nature of the mismatch between charge- and atomic- centers induced by a remarkable double-band inversion. This one-dimensional protected edge state preserves the Luttinger liquid behavior with robustness and universality in scale from micro- to macro- size, leading to a significant anisotropic electrical transport through two-dimensional sides of bulk materials. Moreover, the bulk gap can be modulated by the thickness, resulting in an extensive-range phase diagram for Luttinger liquid. These provide an attractive model to study the interaction and quantum phases in correlated topological systems. The interplay of electronic correlations and topology has been a forefront topic in condensed matter physics. Wang et al. present evidence of a correlated topological edge state supporting the Luttinger liquid behaviour in the candidate quadrupole topological insulator Ta2Pd3Te5. [ABSTRACT FROM AUTHOR]

One-dimensional conductors are described by Luttinger liquid theory, which predicts a power-law suppression of the single-electron tunneling density of states at low voltages. The scaling exponent is predicted to be quantized when tunneling into a single isolated chiral edge state of the fractional quantum Hall effect. We report conductance measurements across a point contact linking integer and fractional quantum Hall edge states (at fillings 1 and 1 3, respectively). At weak coupling, we observe the predicted universal quadratic scaling with temperature and voltage. At strong coupling, we demonstrate perfect Andreev reflection of fractionalized quasiparticles at the point contact. We use the strong coupling physics to realize a nearly dissipationless direct current voltage step-up transformer, whose gain arises directly from topological fractionalization of electrical charge. [ABSTRACT FROM AUTHOR]

Interacting electrons in one dimension (1D) are governed by the Luttinger liquid (LL) theory in which excitations are fractionalized. Can a LL-like state emerge in a 2D system as a stable zero-temperature phase? This question is crucial in the study of non-Fermi liquids. A recent experiment identified twisted bilayer tungsten ditelluride (tWTe2) as a 2D host of LL-like physics at a few kelvins. Here we report evidence for a 2D anisotropic LL state down to 50 mK, spontaneously formed in tWTe2 with a twist angle of ~ 3o. While the system is metallic-like and nearly isotropic above 2 K, a dramatically enhanced electronic anisotropy develops in the millikelvin regime. In the anisotropic phase, we observe characteristics of a 2D LL phase including a power-law across-wire conductance and a zero-bias dip in the along-wire differential resistance. Our results represent a step forward in the search for stable LL physics beyond 1D. Recently, a Luttinger liquid state was reported in a moiré superlattice of bilayer tungsten ditelluride at small twist angles and temperatures of a few kelvins. Here, the authors extend this result to millikelvin temperatures, supporting the existence of the 2D anisotropic Luttinger liquid as a stable ground state. [ABSTRACT FROM AUTHOR]

The expression for the conductance of a 1D channel, which has been obtained using the well-known exact solution, is analyzed. It is shown that in the case of strong electron—electron interaction, the slowest (linear in frequency) asymptotics of the conductance is determined by the behavior of electron—electron interaction in the region of transition from 1D to 3D motion realized near the impurity. [ABSTRACT FROM AUTHOR]

2D charge density wave (CDW) materials receive much attention for high responsivity and broadband photodetection in recent years due to their collective electron transport and narrow bandgap. However, the high dark current density problem hinders their real application. Here, a sharp CDW transition in quasi‐1D (TaSe4)2I is reported and applied for broadband photodetection. Especially at mid‐infrared region, the device shows both high photo responsivity of 1.18 ×103 A W−1 and large light on/off ratio of 80, which is superior to 2D CDW TaS2 and most reported low‐dimensional materials. Such high performance relies on two aspects. One is the much lower dark current density resulting from the pseudo gap associated with 1D Luttinger liquid state, which is supported by finite size scaling of nonlinear I–V at variable temperatures and occurrence of 1D structural phase transition consolidated by in situ Raman spectroscopy. The other is the high photocurrent associated with the "Fröhlich superconductivity" state, manifested by an ultrasensitive switching, which can be only accessible in 1D CDW materials, in agreement with the authors' density functional theory calculation. This work thus reveals the pivotal role of dimensionality in CDW phase transition and paves a way for implementing highly sensitive broadband photodetector. [ABSTRACT FROM AUTHOR]

Electrons injected into one-dimensional (1D) metals are efficiently converted into infrared plasmons because the unique property of the Luttinger liquid, a strongly correlated electronic matter in one-dimensional (1D) metals, prohibits excitations of other quasiparticles. Using the Luttinger liquid behavior, the electrically driven 1D metals can be used as a feed for optical nanoantennas. Nanoantennas can couple the 1D Luttinger liquid plasmons in the feed to the radiating photons in free space. In this work, we suggest design principles for the 1D metallic Luttinger liquid feed and the nanoantennas to obtain high injection and radiation efficiencies, respectively. We expect that our work can promote experimental efforts to realize electrically driven Luttinger liquid-fed nanoantennas and efficient infrared light sources. [ABSTRACT FROM AUTHOR]

Metals in one spatial dimension are described at the lowest energy scales by the Luttinger liquid theory. It is well understood that this free theory, and even interacting integrable models, can support ballistic transport of conserved quantities including energy. In contrast, realistic one-dimensional metals, even without disorder, contain integrability-breaking interactions that are expected to lead to thermalization and conventional diffusive linear response. We argue that the expansion of energy when such a nonintegrable Luttinger liquid is locally heated above its ground state shows superdiffusive behavior (i.e., spreading of energy that is intermediate between diffusion and ballistic propagation), by combining an analytical anomalous diffusion model with numerical matrix-product-state calculations on a specific perturbed spinless fermion chain. Different metals will have different scaling exponents and shapes in their energy spreading, but the superdiffusive behavior is stable and should be visible in time-resolved experiments.

The Tomonaga–Luttinger liquid (TLL) theory describes the low-energy excitations of strongly correlated one-dimensional (1D) fermions. In the past years, a number of studies have provided a detailed understanding of this universality class. More recently, theoretical investigations that go beyond the standard low-temperature, linear-response TLL regime have been developed. While these provide a basis for understanding the dynamics of the spin-incoherent Luttinger liquid, there are few experimental investigations in this regime. Here we report the observation of a thermally induced, spin-incoherent Luttinger liquid in a 6Li atomic Fermi gas confined to 1D. We use Bragg spectroscopy to measure the suppression of spin-charge separation and the decay of correlations as the temperature is increased. Our results probe the crossover between the coherent and incoherent regimes of the Luttinger liquid and elucidate the roles of the charge and the spin degrees of freedom in this regime. Low-energy excitations of strongly correlated systems are described by the Tomonaga–Luttinger liquid theory. Here the authors employ Bragg spectroscopy to demonstrate a spin-incoherent Luttinger liquid in 6Li atoms using charge and spin excitations. [ABSTRACT FROM AUTHOR]

We present a comprehensive study shedding light on how thermal fluctuations affect correlations in a Bose gas with contact repulsive interactions in one spatial dimension. The pair correlation function, the static structure factor, and the one-body density matrix are calculated as a function of the interaction strength and temperature with the exact ab-initio Path Integral Monte Carlo method. We explore all possible gas regimes from weak to strong interactions and from low to high temperatures. We provide a detailed comparison with a number of theories, such as perturbative (Bogoliubov and decoherent classical), effective (Luttinger liquid) and exact (ground-state and thermal Bethe Ansatz) ones. Our Monte Carlo results exhibit an excellent agreement with the tractable limits and provide a fundamental benchmark for future observations which can be achieved in atomic gases, cavity quantum-electrodynamic and superconducting-circuit platforms. [ABSTRACT FROM AUTHOR]

It is shown that, in a SmMnO3+δ sample cooled in a magnetic field H=0 to 4.2 K, the topological order–disorder phase transition of the spin system occurs within the framework of the Kosterlitz–Thouless XY-model decoupling of pairs of the flat 2D vortices. At the same time, when the sample is cooled in the field H≠0, the transition of the system of spins to a disordered state with increasing temperature occurs in the form of dissociation of pairs of bounded Z2 vortices at the same critical temperature TKT=12 K, which is accompanied by a giant jump in the supermagnetization of the sample. The excitation and decay of low-energy bosons in a 1D metallic Luttinger liquid at temperatures of 0.5 K and 4.2 K during sample remagnetization in the ZFC and FC measurement modes is also studied. [ABSTRACT FROM AUTHOR]

The exact solution to the problem of scattering of one-dimensional attracted fermions on a point impurity, which exists in the Kane–Fisher model is analyzed for a Luttinger parameter equal to 2. The expression obtained for the frequency dependence of the coefficient of fermion reflection from an impurity demonstrates impossibility of extrapolation of results for a relatively weak fermion–fermion interaction to the range of coupling constants on the order of unity. [ABSTRACT FROM AUTHOR]

The T = 0 excitation spectra of the antiferromagnetic ( J > 0 ) anisotropic Heisenberg chain of spins 1/2 are studied using the Bethe Ansatz equations for Δ = cos (π / n) , n = 3 , 4 and 5. The number of unknown functions is n − 1 for Δ = cos (π / n) and can be solved numerically for a finite external field. The low-energy excitations form a Luttinger liquid parametrized by a conformal field theory with conformal charge of c = 1 . For higher energy excitations, the spectral functions display deviations from the Luttinger behavior arising from the curvature in the dispersion. Adding a corrective term of the form of a mobile impurity coupled to the Luttinger liquid modes corrects this difference. The "impurity" is an irrelevant operator, which if treated non-perturbatively, yields the threshold singularities in the one-spinwave particle and hole Green's function correctly. [ABSTRACT FROM AUTHOR]

Controlling the quantum interference in nanoscaled systems has potential application for the realization of high-performance functional devices. In this work, the quantum interference of a T-shaped double-quantum-dot system is studied in detail by evaluation of differential conductance by means of nonequilibrium Green's function method. The factors of Coulomb interaction in Luttinger liquid leads, electron–phonon interaction, interdot tunneling, and dot-lead coupling are taken into account. In the differential conductance curve, there appear a series of antiresonance dips due to phonon-assisted destructive interference when the interdot tunneling is weak, and they can coexist with zero-bias antiresonance dip. When the dot-lead couplings are asymmetric, both the antiresonance dip and Fano line shape dip can occur for strong dot-lead coupling. Our results also show the coexistence of low-bias negative differential conductance and Fano antiresonance, as a manifestation of the interplay between strong intralead Coulomb interaction and weak dot-lead coupling. These interference phenomena emerged in a relatively simple model promises helpful guidance for controlling over the electrical performance of interference-based molecular devices. • Manipulating quantum interference in T-shaped coupled vibrating moleculars is explored. • The effect of intralead Coulomb and electron–phonon interactions on interference is studied. • There appeared sets of antiresonance dips due to phonon-assisted destructive interference. • The coexistence of zero-bias antiresonance dip and Fano line shape dip occurs for dot-lead asymmetric coupling. • There shows the coexistence of low-bias negative differential conductance and Fano antiresonance. [ABSTRACT FROM AUTHOR]

We consider the edge transport properties of a generic class of interacting quantum Hall systems on a cylinder, in the infinite volume and zero temperature limit. We prove that the large-scale behavior of the edge correlation functions is effectively described by the multi-channel Luttinger model. In particular, we prove that the edge conductance is universal, and equal to the sum of the chiralities of the non-interacting edge modes. The proof is based on rigorous renormalization group methods, that allow to fully take into account the effect of backscattering at the edge. Universality arises as a consequence of the integrability of the emergent multi-channel Luttinger liquid combined with lattice Ward identities for the microscopic 2d theory. [ABSTRACT FROM AUTHOR]

In one-dimensional (1D) systems, electronic interactions lead to a breakdown of Fermi liquid theory and the formation of a Tomonaga-Luttinger Liquid (TLL). The strength of its many-body correlations can be quantified by a single dimensionless parameter, the Luttinger parameter K, characterising the competition between the electrons' kinetic and electrostatic energies. Recently, signatures of a TLL have been reported for the topological edge states of quantum spin Hall (QSH) insulators, strictly 1D electronic structures with linear (Dirac) dispersion and spin-momentum locking. Here we show that the many-body interactions in such helical Luttinger Liquid can be effectively controlled by the edge state's dielectric environment. This is reflected in a tunability of the Luttinger parameter K, distinct on different edges of the crystal, and extracted to high accuracy from the statistics of tunnelling spectra at tens of tunnelling points. The interplay of topology and many-body correlations in 1D helical systems has been suggested as a potential avenue towards realising non-Abelian parafermions. In one-dimensional systems, electronic interactions lead to a breakdown of Fermi liquid theory and the formation of a Tomonaga Luttinger Liquid (TLL), as recently reported in the helical edge states of quantum spin Hall insulators. Here, the authors show that the many-body interactions in the helical TLL of 1T'- WTe2 can be effectively controlled by the dielectric screening via the substrate. [ABSTRACT FROM AUTHOR]

Traditional spectroscopy, by its very nature, characterizes physical system properties in the momentum and frequency domains. However, the most interesting and potentially practically useful quantum many-body effects emerge from local, short-time correlations. Here, using inelastic neutron scattering and methods of integrability, we experimentally observe and theoretically describe a local, coherent, long-lived, quasiperiodically oscillating magnetic state emerging out of the distillation of propagating excitations following a local quantum quench in a Heisenberg antiferromagnetic chain. This "quantum wake" displays similarities to Floquet states, discrete time crystals and nonlinear Luttinger liquids. We also show how this technique reveals the non-commutativity of spin operators, and is thus a model-agnostic measure of a magnetic system's "quantumness." It has long been suggested that the inverse Fourier transform of neutron scattering data gives access to space- and time-resolved spin-spin correlations. Scheie et al. perform this procedure on high-precision experimental data from a 1D quantum antiferromagnet and uncover new features in short-term quench dynamics. [ABSTRACT FROM AUTHOR]

We study the multi-charged moments for two disjoint intervals in the ground state of two 1 + 1 dimensional CFTs with central charge c = 1 and global U(1) symmetry: the massless Dirac field theory and the compact boson (Luttinger liquid). For this purpose, we compute the partition function on the higher genus Riemann surface arising from the replica method in the presence of background magnetic fluxes between the sheets of the surface. We consider the general situation in which the fluxes generate different twisted boundary conditions at each branch point. The obtained multi-charged moments allow us to derive the symmetry resolution of the Rényi entanglement entropies and the mutual information for non complementary bipartitions. We check our findings against exact numerical results for the tight-binding model, which is a lattice realisation of the massless Dirac theory. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) bilayers, twisted to particular angles to display electronic flat bands, are being extensively explored for physics of strongly correlated 2D systems. However, the similar rich physics of one-dimensional (1D) strongly correlated systems remains elusive as it is largely inaccessible by twists. Here, a distinctive way to create 1D flat bands is proposed, by either stamping or growing a 2D monolayer on a non-Euclidean topography-patterned surface. Using boron nitride (hBN) as an example, our analysis employing elastic plate theory, density-functional and coarse-grained tight-binding method reveals that hBN's bi-periodic sinusoidal deformation creates pseudo- electric and magnetic fields with unexpected spatial dependence. A combination of these fields leads to anisotropic confinement and 1D flat bands. Moreover, changing the periodic undulations can tune the bandwidth, to drive the system to different strongly correlated regimes such as density waves, Luttinger liquid, and Mott insulator. The 1D nature of these states differs from those obtained in twisted materials and can be exploited to study the exciting physics of 1D quantum systems. Flat electronic bands and the ensuing correlated phases have been explored in twisted 2D bilayers and in periodically buckled graphene. Here the authors propose a strategy to realize 1D flat bands with a tunable bandwidth in a 2D semiconductor deposited on a patterned substrate with a non-zero Gaussian curvature. [ABSTRACT FROM AUTHOR]

Understanding the effect of correlations in interacting many-body systems is one of the main challenges in quantum mechanics. While the general problem can only be addressed by approximate methods and numerical simulations, in some limiting cases, it is amenable to exact solutions. This Review collects the predictions coming from a family of exact solutions which allows us to obtain the many-body wavefunction of strongly correlated quantum fluids confined by a tight waveguide and subjected to any form of longitudinal confinement. It directly describes the experiments with trapped ultracold atoms where the strongly correlated regime in one dimension has been achieved. The exact solution applies to bosons, fermions, and mixtures. It allows us to obtain experimental observables such as the density profiles and momentum distribution at all momentum scales, beyond the Luttinger liquid approach. It also predicts the exact quantum dynamics at all the times, including the small oscillation regime yielding the collective modes of the system and the large quench regime where the system parameters are changed considerably. The solution can be extended to describe finite-temperature conditions, spin, and magnetization effects. The Review illustrates the idea of the solution, presents the key theoretical achievements, and the main experiments on strongly correlated one-dimensional quantum gases. [ABSTRACT FROM AUTHOR]

In this paper, we establish a model to realize the photon-assisted destructive interference phenomena, the model consisting of parallel-coupled double quantum dots and Luttinger liquid leads. By applying the canonical transformation and the nonequilibrium Green's function technique, the general time-dependent current formula is developed. The joint effects of the intralead Coulomb interaction and an external ac field on the quantum interference are investigated. For weak intralead interactions, besides the usual photon-assisted tunneling resonance, there are two types of photon-assisted tunneling destructive interference: one is related to interdot coupling and the other to intralead interactions. For moderately strong intralead interaction, the photon-assisted sidebands are suppressed and the differential conductance scales as a power law in bias voltage. In particular, we show the multiphoton absorption and emission up to four photons in an electron tunneling process. We believe that the photo-assisted destructive interference results obtained in this paper are instructive for future experiments. • Interplay of intralead interaction and ac field on the interference is studied. • For Fermi liquid, there occur photon-assisted resonance and antiresonance. • For weak intralead interaction, two types of photon-assisted antiresonances occur. • For strong intralead interaction, a power-law scaling behavior occurs. • The multiphoton absorption and emission up to four photons are achieved. [ABSTRACT FROM AUTHOR]

In this paper, we consider the topological abelian BF theory with radial boundary on a generic 3D manifold, as we were motivated by the recently discovered accelerated edge modes on certain Hall systems. Our aim was to research if, where, and how the boundary keeps the memory of the details of the background metrics. We discovered that some features were topologically protected and did not depend on the bulk metric. The outcome was that these edge excitations were a c c e l e r a t e d , as a direct consequence of the non-flat nature of the bulk spacetime. We found three possibilities for the motion of the edge quasiparticles: same directions, opposite directions, and a single-moving mode. However, requiring that the Hamiltonian of the 2D theory is bounded by below, the case of the edge modes moving in the same direction was ruled out. Systems involving parallel Hall currents (for instance, a fractional quantum Hall effect with ν = 2 / 5 ) cannot be described by a BF theory with the boundary, independently from the geometry of the bulk spacetime, because of positive energy considerations. Thus, we were left with physical situations characterized by edge excitations moving with opposite velocities (for example, the fractional quantum Hall effect with ν = 1 − 1 / n , with the n positive integer, and the helical Luttinger liquids phenomena) or a single-moving mode (quantum anomalous Hall). A strong restriction was obtained by requiring time reversal symmetry, which uniquely identifies modes with equal and opposite velocities, and we know that this is the case of topological insulators. The novelty, with respect to the flat bulk background, is that the modes have local velocities, which correspond to topological insulators with a c c e l e r a t e d edge modes. [ABSTRACT FROM AUTHOR]

In this work, zero-temperature phase diagrams of cuprates with Ba 2 CuO 3 -type CuO chain structure are investigated. The projective symmetry group analysis is employed in the strong coupling limit, and the one-loop renormalization group with bosonization analysis is employed in the weak coupling limit. We find that in both of these two limits, large areas of the phase diagrams are filled with nodeless superconducting phases, instead of nodal d-wave phase mostly found in cuprates. This implies that nodeless superconducting phases are the dominant superconducting phases in cuprates with Ba 2 CuO 3 -type CuO chain structure in low temperature. Other phases are also found, including nodal superconducting phases and Luttinger liquid phases. [ABSTRACT FROM AUTHOR]

In this article, we review the experimental studies in pursuit of supersolidity and on recent studies of mass flow through solid 4He samples. [ABSTRACT FROM AUTHOR]

We review the solution of QCD in two spacetime dimensions. Following the analysis of Baluni, for a single flavor, the model can be analyzed using Abelian bosonization. The theory can be analyzed in strong coupling, when the quarks are much lighter than the gauge coupling. In this limit, the theory is given by a Luttinger liquid. [ABSTRACT FROM AUTHOR]

(Quasi-)one-dimensional systems exhibit various fascinating properties such as Luttinger liquid behavior, Peierls transition, novel topological phases, and the accommodation of unique quasiparticles (e.g., spinon, holon, and soliton, etc.). Here we study molybdenum blue bronze A0.3MoO3 (A = K, Rb), a canonical quasi-one-dimensional charge-density-wave material, using laser-based angle-resolved photoemission spectroscopy. Our experiment suggests that the normal phase of A0.3MoO3 is a prototypical Luttinger liquid, from which the charge-density-wave emerges with decreasing temperature. Prominently, we observe strong renormalizations of band dispersions, which are recognized as the spectral function of Holstein polaron derived from band-selective electron-phonon coupling in the system. We argue that the strong electron-phonon coupling plays an important role in electronic properties and the charge-density-wave transition in blue bronzes. Our results not only reconcile the long-standing heavy debates on the electronic properties of blue bronzes but also provide a rare platform to study interesting excitations in Luttinger liquid materials. The mechanism of the charge density wave transition in quasi one-dimensional blue bronzes is still debated. Here, the authors report evidence of a Luttinger liquid in the normal state of blue bronzes and Holstein polarons below the transition temperature, revealing the important role of electron-phonon coupling in the transition. [ABSTRACT FROM AUTHOR]

We study the stability of multiple conducting edge states in a topological insulator against perturbations allowed by the time-reversal symmetry. A system is modeled as a multi-channel Luttinger liquid, with the number of channels equal to the number of Kramers doublets at the edge. Assuming strong interactions and weak disorder, we first formulate a low-energy effective theory for a clean translation invariant system and then include the disorder terms allowed by the time-reversal symmetry. In a clean system with N Kramers doublets, N − 1 edge states are gapped by Josephson couplings and the single remaining gapless mode describes collective motion of Cooper pairs synchronous across the channels. Disorder perturbation in this regime, allowed by the time reversal symmetry is a simultaneous backscattering of particles in all N channels. Its relevance depends strongly on the parity if the number of channel N is not very large. Our main result is that disorder becomes irrelevant with the increase of the number of edge modes leading to the stability of the edge states superconducting regime even for repulsive interactions. [ABSTRACT FROM AUTHOR]

Domain walls in fractional quantum Hall ferromagnets are gapless helical one-dimensional channels formed at the boundaries of topologically distinct quantum Hall (QH) liquids. Naïvely, these helical domain walls (hDWs) constitute two counter-propagating chiral states with opposite spins. Coupled to an s-wave superconductor, helical channels are expected to lead to topological superconductivity with high order non-Abelian excitations1–3. Here we investigate transport properties of hDWs in the ν = 2/3 fractional QH regime. Experimentally we found that current carried by hDWs is substantially smaller than the prediction of the naïve model. Luttinger liquid theory of the system reveals redistribution of currents between quasiparticle charge, spin and neutral modes, and predicts the reduction of the hDW current. Inclusion of spin-non-conserving tunneling processes reconciles theory with experiment. The theory confirms emergence of spin modes required for the formation of fractional topological superconductivity. Previous work has shown that helical domain walls can form between states of different spin-polarization during a ferromagnetic spin transition in the fractional quantum Hall regime. Here, the authors study the transport through a single helical domain wall and find strong deviations from a simplified theory of weakly interacting edge channels. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) solids exhibit a number of striking electronic structures including chargedensity wave (CDW) and spin-density wave (SDW). Also, the Peierls theorem states that at zero temperature, a 1D system predicted by simple band theory to be a metal will spontaneously dimerize and open a finite fundamental bandgap, while at higher temperatures, it will assume the equidistant geometry with zero bandgap (a Peierls transition). We computationally study these unique electronic structures and transition in polyyne and all-trans polyacetylene using finite-temperature generalizations of ab initio spin-unrestricted Hartree-Fock (UHF) and spin-restricted coupled-cluster doubles (CCD) theories, extending upon previous work [He et al., J. Chem. Phys. 140, 024702 (2014)] that is based on spin-restricted Hartree-Fock (RHF) and second-order many-body perturbation (MP2) theories. Unlike RHF, UHF can predict SDW as well as CDW and metallic states, and unlike MP2, CCD does not diverge even if the underlying RHF reference wave function is metallic. UHF predicts a gapped SDW state with no dimerization at low temperatures, which gradually becomes metallic as the temperature is raised. CCD, meanwhile, confirms that electron correlation lowers the Peierls transition temperature. Furthermore, we show that the results from all theories for both polymers are subject to a unified interpretation in terms of the UHF solutions to the Hubbard-Peierls model using different values of the electron-electron interaction strength, U/t, in its Hamiltonian. The CCD wave function is shown to encompass the form of the exact solution of the Tomonaga-Luttinger model and is thus expected to describe accurately the electronic structure of Luttinger liquids. [ABSTRACT FROM AUTHOR]

Surface plasmons, collective electromagnetic excitations coupled to conduction electron oscillations, enable the manipulation of light–matter interactions at the nanoscale. Plasmon dispersion of metallic structures depends sensitively on their dimensionality and has been intensively studied for fundamental physics as well as applied technologies. Here, we report possible evidence for gate-tunable hybrid plasmons from the dimensionally mixed coupling between one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene. In contrast to the carrier density-independent 1D Luttinger liquid plasmons in bare metallic carbon nanotubes, plasmon wavelengths in the 1D-2D heterostructure are modulated by 75% via electrostatic gating while retaining the high figures of merit of 1D plasmons. We propose a theoretical model to describe the electromagnetic interaction between plasmons in nanotubes and graphene, suggesting plasmon hybridization as a possible origin for the observed large plasmon modulation. The mixed-dimensional plasmonic heterostructures may enable diverse designs of tunable plasmonic nanodevices. Surface plasmons have unique physical properties that make them also interesting for technology. Here, the authors observe plasmons in mixed-dimensional heterostructures that can be highly modulated with electrostatic gating, which may be explained by plasmon hybridization [ABSTRACT FROM AUTHOR]

In this work we discuss extensions of the pioneering analysis by Dzyaloshinskii and Larkin [Sov. Phys. JETP 38, 202 (1974)] of correlation functions for one-dimensional Fermi systems, focusing on the effects of quasiparticle relaxation enabled by a nonlinear dispersion. Throughout the work we employ both, the weakly interacting Fermi gas picture and nonlinear Luttinger liquid theory to describe attenuation of excitations and explore the fermion-boson duality between both approaches. Special attention is devoted to the role of spin-exchange processes, effects of interaction screening, and integrability. Thermalization rates for electron- and hole-like quasiparticles, as well as the decay rate of collective plasmon excitations and the momentum space mobility of spin excitations are calculated for various temperature regimes. The phenomenon of spin–charge drag is considered and the corresponding momentum transfer rate is determined. We further discuss how momentum relaxation due to several competing mechanisms, viz. triple electron collisions, electron–phonon scattering, and long-range inhomogeneities affect transport properties, and highlight energy transfer facilitated by plasmons from the perspective of the inhomogeneous Luttinger liquid model. Finally, we derive the full matrix of thermoelectric coefficients at the quantum critical point of the first conductance plateau transition, and address magnetoconductance in ballistic semiconductor nanowires with strong Rashba spin–orbit coupling. [ABSTRACT FROM AUTHOR]

We investigate electronic transport properties of field-effect transistors based on double-walled carbon nanotubes, of which inner shells are metallic and outer shells are semiconducting. When both shells are turned on, electron-phonon scattering is found to be the dominant phenomenon. On the other hand, when outer semiconducting shells are turned off, a zero-bias anomaly emerges in the dependence of differential conductance on the bias voltage, which is characterized according to the Tomonaga-Luttinger liquid model describing tunneling into one-dimensional materials. We attribute these behaviors to different contact conditions for outer and inner shells of the double-walled carbon nanotubes. A simple model combining Luttinger liquid model for inner metallic shells and electron-phonon scattering in outer semiconducting shells is given here to explain our transport data at different temperatures. [ABSTRACT FROM AUTHOR]

Organic conjugated polymers demonstrate great potential in transistors, solar cells and light-emitting diodes, whose performances are fundamentally governed by charge transport. However, the morphology–property relationships and the underpinning charge transport mechanisms remain unclear. Particularly, whether the nonlinear charge transport in conducting polymers is appropriately formulated within non-Fermi liquids is not clear. In this work, via varying crystalline degrees of samples, we carry out systematic investigations on the charge transport nonlinearity in conducting polymers. Possible charge carriers' dimensionality is discussed when varying the molecular chain's crystalline orders. A heterogeneous-resistive-network (HRN) model is proposed based on the tied-link between Fermi liquids (FL) and Luttinger liquids (LL), related to the high-ordered crystalline zones and weak-coupled amorphous regions, respectively. The HRN model is supported by precise electrical and microstructural characterizations, together with theoretic evaluations, which well describes the nonlinear transport behaviors and provides new insights into the microstructure-correlated charge transport in organic solids. The mechanism of nonlinear charge transport in doped conducting polymers remains elusive. Here, Wang et al. study charge transport with respect to crystalline degrees of samples and construct a model based on the tied link between Fermi liquids and Luttinger liquids, providing a universal explanation to understand nonlinear charge transport in conducting polymers. [ABSTRACT FROM AUTHOR]

In this paper, we employ three dimensionless system parameters, induced by the contrast of the wave vector, geometric size, and wave impedance of two materials, to analyze the band structure characteristics of a one-dimensional photonic system. We have obtained the dependence relationships of the bandgap position, width, and depth on the dimensionless system parameters. Moreover, we also work out the relationships between the wave vector and geometric size contrast ratios, which can reveal the occurrence of topological phase transitions. These properties should be especially helpful for manipulating the bandgap in novel devices based on a one-dimensional photonic system. [ABSTRACT FROM AUTHOR]

Computing phase diagrams of model systems is an essential part of computational condensed matter physics. In this paper, we discuss in detail the interface pinning (IP) method for calculation of the Gibbs free energy difference between a solid and a liquid. This is done in a single equilibrium simulation by applying a harmonic field that biases the system towards two-phase configurations. The Gibbs free energy difference between the phases is determined from the average force that the applied field exerts on the system. As a test system, we study the Lennard-Jones model. It is shown that the coexistence line can be computed efficiently to a high precision when the IP method is combined with the Newton-Raphson method for finding roots. Statistical and systematic errors are investigated. Advantages and drawbacks of the IP method are discussed. The high pressure part of the temperature-density coexistence region is outlined by isomorphs. [ABSTRACT FROM AUTHOR]

The degenerate Bose–Fermi (BF) mixtures in one dimension present a novel realization of two decoupled Luttinger liquids with bosonic and fermionic degrees of freedom at low temperatures. However, the transport properties of such decoupled Luttinger liquids of charges is little known. Here we report on the transport properties of one-dimensional (1D) BF mixtures with delta-function interactions. The initial state is set up as the semi-infinite halves of two 1D BF mixtures with different temperatures, joined together at the time t = 0 and the junction point x = 0. Using the Bethe ansatz solution, we first rigorously prove the existence of conserved charges for both the bosonic and fermionic degrees of freedom, preserving the Euler-type continuity equations. Applying generalized hydrodynamics, we then analytically obtain the distributions of the densities and currents of the local conserved quantities which solely depend on the ratio ξ = x/t. The left and right moving quasiparticle excitations of the two halves form multiple segmented light-cone hydrodynamics that display ballistic transport of the conserved charge densities and currents in different degrees of freedom. Such profiles reveal a novel dynamical separation of the two Luttinger liquids of fermionic and bosonic atoms in 1D. Our analytical results provide a deep understanding of the role of interaction and quantum statistical effects in quantum transport. [ABSTRACT FROM AUTHOR]

Pulsed NMR techniques have been used to study the dynamics of 3 He confined to the interior of the hexagonal nanochannels of MCM-41 for which the walls were coated with a monolayer of 4 He as determined by isotherm measurements. The 3 He was added afterward to form a 1D 3 He line density of about 0.1 A - 1 , corresponding to a Fermi temperature of T F ∼ 120 mK. A distinct and appreciable departure from the Curie law was observed for the nuclear spin magnetization below 0.5 K. The temperature dependence of the nuclear spin–lattice relaxation times, T 1 , for temperatures 0.05 < T < 2.5 K, followed the expected linear behavior at low temperatures, and a peak was observed at T ∼ 2 T F consistent with the Luttinger liquid theory as predicted by Polini et al. (Phys Rev Lett 98:266403, 2007). The observed temperature dependence of the nuclear spin–spin relaxation times, T 2 , differed considerably from that observed for T 1 , with a minimum at T = 0.8 K, similar to the tendency reported by Matsushita and colleagues. [ABSTRACT FROM AUTHOR]

We have studied one dimensional acoustic phonon linearly coupled to the electron density. The phonon spectrum is linear with cutoff at the Debye frequency, it is straightforward modification of three dimensional optical phonons. Phonon field results in substituting the dynamical coupling for the screened coulomb interaction. We have shown that the electron-phonon coupling quantitatively changed the phase diagram of Luttinger liquid with a single impurity. The existence of slow and fast polaron modes with different weights in different regimes resulted in different renormalization group flow for a weak scatterer and a weak tunneling link. The resulting phase diagram depending on the parameters of the problem, regimes corresponding to purely metallic or purely insulating behavior and an intermediate regime with two stable fixed points and one unstable, finite conductance fixed point. we have found that the direction of renormalization group flow change upon varying either the relative strength of the electron-electron and electron-phonon coupling or the ratio of Fermi to sound velocities. The obtained results were found in good agreement with previously obtained results. [ABSTRACT FROM AUTHOR]

We consider the interacting helical liquid system at the one-dimensional edge of a two-dimensional topological insulator, coupled to an external magnetic field and s-wave superconductor and map it to an XYZ spin chain system. This model undergoes quantum Berezinskii–Kosterlitz–Thouless (BKT) transition with two limiting conditions. We derive the renormalization group (RG) equations explicitly and also present the flow lines behavior. We also present the behavior of RG flow lines based on the exact solution. We observe that the physics of Majorana fermion zero modes and the gaped Ising-ferromagnetic phase, which appears in a different context. We observe that the evidence of gapless helical Luttinger liquid phase as a common non-topological quantum phase for both quantum BKT transitions. We explain analytically and physically that there is no Majorana-Ising transition. In the presence of chemical potential, the system shows the commensurate to incommensurate transition. [ABSTRACT FROM AUTHOR]

Coupled-wire constructions use bosonization to analytically tackle the strong interactions underlying fractional topological states of matter. We give an introduction to this technique, discuss its strengths and weaknesses, and provide an overview of the main achievements of coupled-wire constructions. [ABSTRACT FROM AUTHOR]

In atomically-thin two-dimensional (2D) semiconductors, the nonuniformity in current flow due to its edge states may alter and even dictate the charge transport properties of the entire device. However, the influence of the edge states on electrical transport in 2D materials has not been sufficiently explored to date. Here, we systematically quantify the edge state contribution to electrical transport in monolayer MoS2/WSe2 field-effect transistors, revealing that the charge transport at low temperature is dominated by the edge conduction with the nonlinear behavior. The metallic edge states are revealed by scanning probe microscopy, scanning Kelvin probe force microscopy and first-principle calculations. Further analyses demonstrate that the edge-state dominated nonlinear transport shows a universal power-law scaling relationship with both temperature and bias voltage, which can be well explained by the 1D Luttinger liquid theory. These findings demonstrate the Luttinger liquid behavior in 2D materials and offer important insights into designing 2D electronics. Though metallic edge states in monolayer transition metal dichalcogenide have been observed before, how these states contribute to charge transport remains unclear. Here, the authors quantify the edge state contribution to electrical transport in monolayer MoS2/WSe2 field-effect transistors, revealing a dominated non-linear edge transport at low temperature, indicating possible Luttinger liquid behavior. [ABSTRACT FROM AUTHOR]

Elementary particles carry several quantum numbers, such as charge and spin. However, in an ensemble of strongly interacting particles, the emerging degrees of freedom can fundamentally differ from those of the individual constituents. For example, one-dimensional systems are described by independent quasiparticles carrying either spin (spinon) or charge (holon). Here, we report on the dynamical deconfinement of spin and charge excitations in real space after the removal of a particle in Fermi-Hubbard chains of ultracold atoms. Using space- and time-resolved quantum gas microscopy, we tracked the evolution of the excitations through their signatures in spin and charge correlations. By evaluating multipoint correlators, we quantified the spatial separation of the excitations in the context of fractionalization into single spinons and holons at finite temperatures. [ABSTRACT FROM AUTHOR]

The spin-1/2 two-leg ladders with dominant spatially modulated rung exchanges are known as the dimerized ladders. In the limit of strong rung exchange, the ground state of the system is in the rung-singlet (RS) gapped phase. Applying an external magnetic field creates two additional new gapped phases in the ground-state phase diagram of the model beside the existence of the two trivial gapless Luttinger liquid (LL) phases. It is already specified that the magnetization curve of the system exhibits a plateau at magnetization which is equal to the half of the saturation value in one of the non-trivial gapped phases known as the mid-plateau state. Here, we calculate the entanglement entropy and entanglement spectrum (ES) for finite ladder systems using the numerical Lanczos method. In fact, it has been suggested that the topological properties of the ground state can be reflected by specific degeneracy of the ES. We investigate the gapped RS and the mid-plateau phases where our outcomes show even degeneracy in the ES in the non-trivial RS and mid-plateau gapped phases is an indication of the symmetry-protected topological phases. In addition, we argue about the difference between the results of ES for various divisions of the ladder system. [ABSTRACT FROM AUTHOR]

In this work, we propose a theoretical model, a series-coupled vibrating double-quantum dots adiabatically connected to Luttinger liquid leads, to realize the controllability of quantum interference and decoherence. By means of the nonequilibrium Green function approach and Lang-Firsov canonical transformation technique, we investigate the effects of the intralead Coulomb interaction, interdot tunneling, and electron-phonon interactions on differential conductance. In the strong dot-lead tunneling regions the antiresonance features of destructive interference, Fano interference, and negative differential conductance (NDC) appear in the case of moderately strong intralead Coulomb interaction and electron-phonon interaction, and they can coexist under appropriate gate voltages. With the increase of the intralead interaction, the quantum interference is first enhanced and then weakened, and eventually decoherence emerges, leading to the disappearance of the intriguing features. In the weak dot-lead tunneling regime, there appears a characteristic pattern of positive and negative differential conductances. It is stressed that there is no requirement of the asymmetry in this system for the occurrence of the NDC and antiresonance dip. These results offer an understanding of the structure relationships between the quantum interference effects and parameters, which enables us to manipulate the quantum interference behavior of multi-functional devices in the future. • Manipulating quantum interference and decoherence in serially-coupled vibrating molecular is explored. • Antiresonance, Fano interference and negative differential conductance appear in strong tunneling regions. • Alternating positive and negative differential conductance appear in weak tunneling regions. • Asymmetry is not required for the occurrence of the NDC and antiresonance. • Increasing intralead Coulomb interaction induces the interference enhanced and decoherence. [ABSTRACT FROM AUTHOR]

In this work, we study the thermoelectric properties of the parallel-coupled double quantum dot connected to Luttinger liquid (LL) leads. By applying nonequilibrium Green's function methods, the expressions of the electron current, heat currents, and transport coefficients are derived. We mainly focus on the effect of intralead Coulomb interaction and the spatial asymmetry of the system. Various causes for the enhancement of the thermoelectric efficiency are investigated. We find that Coulomb interactions in the LL not only enhance quantum interference but also considerably enhance thermoelectric effects. For moderately strong intralead interaction, the figure of merit can be considerably high and reach over 60 in the case of weakly coupled to LL leads and detuning of the energy levels, while in the case of strongly coupled to LL leads and the two aligned levels, the figure of merit approaches 8. The quantum interference induced by the Coulomb interaction yields a very high thermoelectric efficiency when the intralead interaction is very strong. These results may provide a design rule for the development of high-efficiency thermoelectric devices and facilitate optimization of device performance. • Parallel double quantum dots with Coulombic interactions in the lead was studied. • Expressions for conductances, Seebeck coefficient and quality factor are derived. • Quantum interference caused by interactions can enhance the thermoelectric effect. • Figure of merit is reaches over 60 under some conditions for moderately interaction. • At very strong interaction, quality factor approach the limit of Carnot efficiency. [ABSTRACT FROM AUTHOR]

The effect of uniform Dzyaloshinskii-Moriya interaction (antisymmetric spin coupling) and arbitrary oriented external magnetic fields in the x̂ and ẑ directions hx, hy, on quantum entanglement is investigated in the quantum spin-1/2 one-dimensional Heisenberg antiferromagnetic model. The Von Neumann entropy of quantum entanglement is calculated employing Abelian bosonization and density matrix renormalization group. We investigate the influence of quantum phase transition of three competing phases (Néel phase, dimerized phase and gapless Luttinger liquid phase) on quantum entanglement at zero-temperature. [ABSTRACT FROM AUTHOR]

Measurements that document a number of the characteristics of 4 He mass flux through a cell filled with solid 4 He carried out at the University of Massachusetts and elsewhere are reviewed. The mass flux is found to be a universal function of temperature, to have nonlinear behavior as a function of the driving chemical potential as might be expected for a Luttinger liquid and the flux can be extinguished at a concentration-dependent temperature by the presence of 3 He . Strong evidence indicates that the flux is carried by the cores of dislocations present in the solid. Some contact with the history of quantum fluids and relevant early work in solid helium is made as is contact with theory related to the notion of a supersolid and mass flux in 4 He . [ABSTRACT FROM AUTHOR]