The numerical renormalization group (NRG) is rephrased as a variational method with the cost function given by the sum of all the energies of the effective low-energy Hamiltonian. This allows us to systematically improve the spectrum obtained by NRG through sweeping. The ensuing algorithm has a lot ...

[Phys. Rev. Lett. 108, 067202] Published Wed Feb 08, 2012

We investigate the low-temperature thermodynamics and correlation functions of one-dimensional spin-1/2 fermions with strong repulsion in an external magnetic field via the thermodynamic Bethe ansatz method. The exact thermodynamics of the model in a weak magnetic field is derived with the help of W...

[Phys. Rev. B 85, 085414] Published Wed Feb 08, 2012

The hole distribution in Sr₁₄Cu₂₄O₄₁ is studied by low-temperature polarization-dependent O K near-edge x-ray absorption fine-structure measurements and state-of-the-art electronic structure calculations that include core-hole and correlation effects in a mean-field approach. Contrary to all previou...

[Phys. Rev. B 85, 075108] Published Tue Feb 07, 2012

We use a non-Markovian master equation to describe the transport of Coulomb-interacting electrons through an electromagnetic cavity with one quantized photon mode. The central system is a finite-parabolic quantum wire that is coupled weakly to external parabolic quasi-one-dimensional leads at t=0. W...

[Phys. Rev. B 85, 075306] Published Mon Feb 06, 2012

Finite-size effects in charge-density waves (CDWs) were unveiled using scanning tunneling microscopy for metallic atomic wires on the Au/Si(553) surface, as terminated by adsorbate impurities. We found that CDW formed at low temperature adopts the finite-length boundary condition in two distinct way...

[Phys. Rev. B 85, 073401] Published Fri Feb 03, 2012

The Nernst coefficient for the quasi-one-dimensional metal, Li_0.9Mo₆O₁₇, is found to be among the largest known for metals (ν≃500  μV/KT at T∼20  K), and is enhanced in a broad range of temperature by orders of magnitude over the value expected from Boltzmann theory for carrier diffusion. A comparat...

[Phys. Rev. Lett. 108, 056604] Published Thu Feb 02, 2012

Due to the mechanism of confinement, as known from quantum chromodynamics, it is difficult to observe individual particles carrying fractional quantum number (e.g., quark with fractional electric charge). A condensed-matter example of fractionalized particles is spinons in quasi-one-dimensional spin...

[Phys. Rev. B 85, 075102] Published Thu Feb 02, 2012

We study the entanglement spectrum of spin-1/2 XXZ ladders both analytically and numerically. Our analytical approach is based on perturbation theory starting either from the limit of strong rung coupling, or from the opposite case of dominant coupling along the legs. In the former case we find to l...

[Phys. Rev. B 85, 054403] Published Wed Feb 01, 2012

We study theoretically the multiferroic dynamics in a composite one-dimensional system consisting of BaTiO₃ multiferroically coupled to an iron chain. The method treats magnetization and polarization as thermodynamic quantities describable via a combination of the Landau-Lifshits-Gilbert and the Gin...

[Phys. Rev. B 85, 054401] Published Wed Feb 01, 2012

We provide analytic expressions for the Green's functions in position-frequency space as well as for the tunneling density of states of various Luttinger liquids at zero temperature: the standard spinless and spinful Luttinger liquids, the helical Luttinger liquid at the edge of a topological insula...

[Phys. Rev. B 85, 035136] Published Tue Jan 31, 2012

A gas of ultracold ⁶Li atoms (effective spin 1/2) confined to an elongated trap with one-dimensional properties is a candidate to display three different phases: (i) fermions bound in Cooper-pair-like states, (ii) unbound spin-polarized particles, and (iii) a mixed phase in which Cooper bound states...

[Phys. Rev. B 85, 024535] Published Mon Jan 30, 2012

We derived the spin dephasing time taking Rashba and Dresselhaus spin-orbit interactions (SOI) into account in a quasi-one-dimensional (1D) system. Our analytical solution based on the semiclassical model describes temporal decay of the ensemble-averaged spin polarization, stability of the persisten...

[Phys. Rev. B 85, 035321] Published Mon Jan 30, 2012

GaAs nanowires (NWs) grown by molecular-beam epitaxy may contain segments of both the zincblende (ZB) and wurtzite (WZ) phases. Depending on the growth conditions, we find that optical emission of such NWs occurs either predominantly above or below the band gap energy of ZB GaAs (E_g^ZB). This result ...

[Phys. Rev. B 85, 045323] Published Mon Jan 30, 2012

Vortices in type-II superconductors are tiny tornados of circulating electric current of a radius of tens of nanometers surrounding a normal-state core. They move, repel each other, and may get pinned by defects. One-dimensional “traffic jams” and intermittent jam-relieving “avalanches” of such vortices in a thin superconducting film with a multiterraced surface are revealed vividly by spatially resolved, real-time magneto-optical images, pointing to interesting new physics.

[Phys. Rev. X 2, 011007] Published Fri Jan 27, 2012

We study the shot noise (nonequilibrium current fluctuation) associated with dynamic nuclear polarization in a nonequilibrium quantum wire (QW) fabricated in a two-dimensional electron gas. We observe that the spin-polarized conductance quantization of the QW in the integer quantum Hall regime colla...

[Phys. Rev. B 85, 041309] Published Thu Jan 26, 2012

In this paper we investigate the effect of terminal substituents on the dynamics of spin and charge transport in donor-acceptor substituted polyenes [D–(CH)_x–A] chains, also known as push-pull polyenes. We employ a long-range correlated model Hamiltonian for the D–(CH)_x–A system, and time-dependent ...

[Phys. Rev. B 85, 035122] Published Wed Jan 25, 2012

We study the real-time emission of single electrons from a quantum dot coupled to a one dimensional conductor, using exact diagonalization on a discrete tight-binding chain. We show that, from the calculation of the time evolution of the one-electron states, we have simple access to all the relevant...

[Phys. Rev. B 85, 045321] Published Wed Jan 25, 2012

We measure Coulomb drag between displaced parallel quantum wires fabricated on a high-mobility two-dimensional electron gas using a split-gate technique. We observe a rectified Coulomb drag, in which the sign of the drag current is the same irrespective of the current direction in the drive wire, wh...

[Phys. Rev. B 85, 041308] Published Wed Jan 25, 2012

We derive the dynamical structure factor for an inhomogeneous Tomonaga-Luttinger liquid (TLL) as can be formed in a confined strongly interacting one-dimensional gas. In view of the current experimental progress in the field, we provide a simple analytic expression for the light-scattering cross sec...

[Phys. Rev. A 85, 013634] Published Wed Jan 25, 2012

Electronic phase diagram of Li_xCoO₂ has been reexamined using potentiostatically de-intercalated single-crystal samples. Stable phases of x∼0.87, 0.72, 0.53, 0.50, 0.43, and 0.33 were found and isolated for physical property studies. A-type and chain-type antiferromagnetic orderings have been sugges...

[Phys. Rev. B 85, 035120] Published Tue Jan 24, 2012

Using the density matrix renormalization group, we calculated the finite-size corrections of the entanglement α-Rényi entropy of a single interval for several critical quantum chains. We considered models with U(1) symmetry such as the spin-1/2 XXZ and spin-1 Fateev-Zamolodchikov models, as well as ...

[Phys. Rev. B 85, 024418] Published Tue Jan 24, 2012

We derive an effective quantum Josephson array model for a weakly interacting one-dimensional condensate that is fragmented into weakly coupled puddles by a disorder potential. The distribution of coupling constants, obtained from first principles, indicates that weakly interacting bosons in a disor...

[Phys. Rev. B 85, 024531] Published Mon Jan 23, 2012

We propose a one-dimensional model of spinor bosons with SU(2) symmetry and a two-body finite-range Gaussian interaction potential. We show that the model is exactly solvable when the width of the interaction potential is much smaller than the interparticle separation. This model is then solved via ...

[Phys. Rev. A 85, 013629] Published Mon Jan 23, 2012

We develop a method to extract the universal conductance of junctions of multiple quantum wires, a property of systems connected to reservoirs, from static ground-state computations in closed finite systems. The method is based on a key relationship, derived within the framework of boundary conforma...

[Phys. Rev. B 85, 045120] Published Fri Jan 20, 2012

In the presence of a scattering potential, electron transport in a quantum wire is known to be dramatically modified by backward-scattering and unaffected by forward-scattering processes. We show that the scenario is quite different in quantum spin Hall edge states coupled at a constriction. The hel...

[Phys. Rev. B 85, 033306] Published Thu Jan 19, 2012

We study how a Luttinger liquid of spinless particles in one dimension approaches thermal equilibrium. Full equilibration requires processes of backscattering of excitations, which occur at energies of the order of the bandwidth. Such processes are not accounted for by the Luttinger-liquid theory. W...

[Phys. Rev. B 85, 041102] Published Thu Jan 19, 2012

We analyze the effects of different coupling anisotropies in a spin-1/2 ladder on the electron spin resonance (ESR) shift. Combining a perturbative expression in the anisotropies with density matrix renormalization group computation of the short range correlations at finite temperature, we provide t...

[Phys. Rev. Lett. 108, 037204] Published Thu Jan 19, 2012

Quantum state transfer in the presence of static disorder and noise is one of the main challenges in building quantum computers. We compare the quantum state transfer properties for two classes of qubit chains under the influence of static disorder. In fully engineered chains all nearest-neighbor co...

[Phys. Rev. A 85, 012318] Published Thu Jan 19, 2012

We have measured the temperature dependence of the conductance of long V-groove quantum wires fabricated using GaAs/AlGaAs heterostructures, in a wide temperature range (200 mK<T<4.2 K). We find that for our quantum wires the Fermi velocity can be as low as v_F≅5×10⁴ m/s, corresponding to an in...

[Phys. Rev. B 85, 045315] Published Wed Jan 18, 2012

We show scanning probe microscopy measurements of metallic nanocontacts between controlled electromigration cycles. The nanowires used for the thinning process are fabricated by shadow evaporation. The highest resolution obtained using scanning force microscopy is about 3 nm. During the first few el...

[Phys. Rev. B 85, 033404] Published Tue Jan 17, 2012