arXiv subjects

L. I. Glazman

Publications and source records attributed to L. I. Glazman.

At least 55 records · Page 3Linked to original sources

arXiv2010

Decay of a plasmon into neutral modes in a carbon nanotube

We evaluate the rate of energy loss of a plasmon in a disorder-free carbon nanotube. The plasmon decays into neutral bosonic excitations of the electron liquid. The process is mediated either by phonon-assisted backscattering of a single electron, or Umklapp backscattering of two electrons. To lowest order in the backscattering interactions the partial decay rates are additive. At zero doping the corresponding decay rates scale as power-laws of the temperature with positive and negative exponents for the two mechanisms, respectively. The precise values of the exponents depend on the Luttinger liquid parameter. At finite doping the decay rates are described by universal crossover functions of frequency and chemical potential measured in units of temperature. In the evaluation of the plasmon decay, we concentrate on a finite-length geometry allowing excitation of plasma resonances.

cond-mat.str-el↗

arXiv2009

The photon absorption edge in superconductors and gapped 1D systems

Opening of a gap in the low-energy excitations spectrum affects the power-law singularity in the photon absorption spectrum $A(Ω)$. In the normal state, the singularity, $A(Ω)\propto [D/(Ω-Ω_{\rm th})]^α$, is characterized by an interaction-dependent exponent $α$. On the contrary, in the supeconducting state the divergence, $A(Ω)\propto (D/Δ)^α(Ω-\tildeΩ_{\rm th})^{-1/2}$, is interaction-independent, while threshold is shifted, $\tildeΩ_{\rm th}=Ω_{\rm th}+Δ$; the ``normal-metal'' form of $A(Ω)$ resumes at $(Ω-\tildeΩ_{\rm th})\gtrsim Δ\exp(1/α)$. If the core hole is magnetic, it creates in-gap states; these states transform drastically the absorption edge. In addition, processes of scattering off the magnetic core hole involving spin-flip give rise to inelastic absorption with one or several {\it real} excited pairs in the final state, yielding a structure of peaks in $A(Ω)$ at multiples of $2Δ$ above the threshold frequency. The above conclusions apply to a broad class of systems, e.g., Mott insulators, where a gap opens at the Fermi level due to the interactions.

cond-mat.mes-hall↗

arXiv2009

Charging effects in the inductively shunted Josephson junction

The choice of impedance used to shunt a Josephson junction determines if the charge transferred through the circuit is quantized: a capacitive shunt renders the charge discrete, whereas an inductive shunt leads to continuous charge. This discrepancy leads to a paradox in the limit of large inductances L. We show that while the energy spectra of the capacitively and inductively shunted junction are vastly different, their high-frequency responses become identical for large L. Inductive shunting thus opens the possibility to observe charging effects unimpeded by charge noise.

cond-mat.mes-hall↗

arXiv2009

Dynamics of a one-dimensional spinor Bose liquid: a phenomenological approach

The ground state of a spinor Bose liquid is ferromagnetic, while the softest excitation above the ground state is the magnon mode. The dispersion relation of the magnon in a one-dimensional liquid is periodic in the wavenumber q with the period 2πn, determined by the density n of the liquid. Dynamic correlation functions, such as e.g. spin-spin correlation function, exhibit power-law singularities at the magnon spectrum, $ω\toω_m(q,n)$. Without using any specific model of the inter-particle interactions, we relate the corresponding exponents to independently measurable quantities $\partialω_m/\partial q$ and $\partialω_m/\partial n$.

cond-mat.mes-hall↗

arXiv2009

Anisotropic Instabilities in Trapped Spinor Bose-Einstein Condensates

We theoretically investigate the effect of an anisotropic trap on the instability of the polar $(m_F=0)$ phase of a spin-1 Bose-Einstein condensate. By considering rigorously the spatial quantization, we show that the growth of the nascent ferromagnetic phase at short times becomes anisotropic with stronger oscillations in the magnetization correlation function along the unconfined direction.

cond-mat.other↗

arXiv2009

Theory of preparation and relaxation of a p-orbital atomic Mott insulator

We develop a theoretical framework to understand the preparation and relaxation of a metastable Mott insulator state within the first excited band of a 1D optical lattice. The state is loaded by "lifting" atoms from the ground to the first excited band by means of a stimulated Raman transition. We determine the effect of pulse duration on the accuracy of the state preparation for the case of a Gaussian pulse shape. Relaxation of the prepared state occurs in two major stages: double-occupied sites occurring due to quantum fluctuations initially lead to interband transitions followed by a spreading of particles in the trap and thermalization. We find the characteristic relaxation times at the earliest stage and at asymptotically long times approaching equilibrium. Our theory is applicable to recent experiments performed with 1D optical lattices [T. Müller, S. Fölling, A. Widera, and I. Bloch, Phys. Rev. Lett. \textbf{99}, 200405 (2007)].

cond-mat.other↗

arXiv2008

Photo-Solitonic Effect

We show that dark solitons in 1D Bose liquids may be created by absorption of a single quanta of an external ac field, in a close analogy with the Einstein's photoelectric effect. Similarly to the von Lenard's experiment with photoexcited electrons, the external field's photon energy $\hbarω$ should exceed a certain threshold. In our case the latter is given by the soliton energy $\varepsilon_s(\hbar q)$ with the momentum $\hbar q$, where $q$ is photon's wavenumber. We find the probability of soliton creation to have a power-law dependence on the frequency detuning $ω-\varepsilon_s/\hbar$. This dependence is a signature of the quantum nature of the absorption process and the orthogonality catastrophe phenomenon associated with it.

cond-mat.other↗

arXiv2008

Effect of disorder on a graphene p-n junction

We propose the theory of transport in a gate-tunable graphene p-n junction, in which the gradient of the carrier density is controlled by the gate voltage. Depending on this gradient and on the density of charged impurities, the junction resistance is dominated by either diffusive or ballistic contribution. We find the conditions for observing ballistic transport and show that in existing devices they are satisfied only marginally. We also simulate numerically the trajectories of charge carriers and illustrate challenges in realizing more delicate ballistic effects, such as Veselago lensing.

cond-mat.mes-hall↗

arXiv2008

Critical conductance of a one-dimensional doped Mott insulator

We consider the two-terminal conductance of a one-dimensional Mott insulator undergoing the commensurate-incommensurate quantum phase transition to a conducting state. We treat the leads as Luttinger liquids. At a specific value of compressibility of the leads, corresponding to the Luther-Emery point, the conductance can be described in terms of the free propagation of non-interacting fermions with charge e/\sqrt{2}. At that point, the temperature dependence of the conductance across the quantum phase transition is described by a Fermi function. The deviation from the Luther-Emery point in the leads changes the temperature dependence qualitatively. In the metallic state, the low-temperature conductance is determined by the properties of the leads, and is described by the conventional Luttinger liquid theory. In the insulating state, conductance occurs via activation of e/\sqrt{2} charges, and is independent of the Luttinger liquid compressibility.

cond-mat.mes-hall↗

arXiv2007

Generating dark solitons by single photons

We show that dark solitons in 1D bose systems may be excited by resonant absorption of single quanta of an external ac field. The energy of the quantum $\hbarω$ should be slightly blue-detuned from the energy of a soliton with momentum $\hbar q$, where $q$ is the external field wavenumber $q$. We calculate the absorption cross-section and show that it has power-law dependence on the frequency detuning. This reflects the quantum nature of the absorption process and the orthogonality catastrophe phenomenon associated with it.

cond-mat.other↗

arXiv2007

Fermi-Luttinger liquid: Spectral function of interacting one-dimensional fermions

We evaluate the spectral function of interacting fermions in one dimension. Contrary to the Tomonaga-Luttinger model, our treatment accounts for the nonlinearity of the free fermion spectrum. In a striking departure from the Luttinger liquid theory, the spectrum nonlinearity restores the main feature of the Fermi liquid: a Lorentzian peak in the spectral function on the particle mass-shell. At the same time, the spectral function displays a power-law singularity on the hole mass-shell, similar to that in the Luttinger liquid.

cond-mat.mes-hall↗

arXiv2007

Dynamics of excitations in a one-dimensional Bose liquid

We show that the dynamic structure factor of a one-dimensional Bose liquid has a power-law singularity defining the main mode of collective excitations. Using the Lieb-Liniger model, we evaluate the corresponding exponent as a function of the wave vector and the interaction strength.

cond-mat.stat-mech↗

arXiv2007

Energy relaxation of superconducting charge qubit via Andreev processes

We study fundamental limitations on the energy relaxation rate of a superconducting charge qubit with a large-gap Cooper-pair box, $Δ_b > Δ_r$. At a sufficiently large mismatch between the gap energies in the box $Δ_b$ and in the reservoir $Δ_r$,"quasiparticle poisoning" becomes ineffective even in the presence of nonequilibrium quasiparticles in the reservoir. The qubit relaxation still may occur due to higher-order (Andreev) processes. In this paper we evaluate the qubit energy relaxation rate due to Andreev processes.

cond-mat.supr-con↗

arXiv2007

Bosonization of strongly interacting electrons

Strong repulsive interactions in a one-dimensional electron system suppress the exchange coupling J of electron spins to a value much smaller than the Fermi energy E_F. The conventional theoretical description of such systems based on the bosonization approach and the concept of Tomonaga-Luttinger liquid is applicable only at energies below J. In this paper we develop a theoretical approach valid at all energies below the Fermi energy, including a broad range of energies between J and E_F. The method involves bosonization of the charge degrees of freedom, while the spin excitations are treated exactly. We use this technique to calculate the spectral functions of strongly interacting electron systems at energies in the range J<<epsilon<< E_F$. We show that in addition to the expected features at the wavevector k near the Fermi point k_F, the spectral function has a strong peak centered at k=0. Our theory also provides analytical description of the spectral function singularities near 3k_F (the "shadow band" features).

cond-mat.mes-hall↗

arXiv2007

Kinetics of quasiparticle trapping in a Cooper-pair box

We study the kinetics of the quasiparticle capture and emission process in a small superconducting island (Cooper-pair box) connected by a tunnel junction to a massive superconducting lead. At low temperatures, the charge on the box fluctuates between two states, even and odd in the number of electrons. Assuming that the odd-electron state has the lowest energy, we evaluate the distribution of lifetimes of the even- and odd-electron states of the Cooper-pair box. The lifetime in the even-electron state is an exponentially distributed random variable corresponding to a homogenous Poisson process of ``poisoning'' the island with a quasiparticle. The distribution of lifetimes of the odd-electron state may deviate from the exponential one. The deviations come from two sources - the peculiarity of the quasiparticle density of states in a superconductor and the possibility of quasiparticle energy relaxation via phonon emission. In addition to the lifetime distribution, we also find spectral density of charge fluctuations generated by capture and emission processes. The complex statistics of the quasiparticle dwell times in the Cooper-pair box may result in strong deviations of the noise spectrum from the Lorentzian form.

cond-mat.mes-hall↗

arXiv2006

Non-linear Resistivity of a Two-Dimensional Electron Gas in a Magnetic Field

We develop a theory of nonlinear response to an electric field of a two-dimensional electron gas (2DEG) placed in a classically strong magnetic field. The latter leads to a non-linear current-voltage characteristic at a relatively weak electric field. The origin of the non-linearity is two-fold: the formation of a non-equilibrium electron distribution function, and the geometrical resonance in the inter-Landau-levels transitions rates. We find the dependence of the current-voltage characteristics on the electron relaxation rates in the 2DEG.

cond-mat.mes-hall↗

arXiv2006

Nonlinear magnetoconductance of a classical ballistic system

We study nonlinear transport through a classical ballistic system accounting for the Coulomb interaction between electrons. The joint effect of the applied bias $V$ and magnetic field $H$ on the electron trajectories results in a component of the non-linear current $I(V,H)$ which lacks the $H\to -H$ symmetry: $δI=α_{cl} V^2 H$. At zero temperature the magnitude of $α_{cl}$ is of the same order as that arising from the quantum interference mechanism. At higher temperatures the classical mechanism is expected to dominate due to its relatively weak temperature dependence.

cond-mat.mes-hall↗

arXiv2006

Kinetics of the superconducting charge qubit in the presence of a quasiparticle

We investigate the energy and phase relaxation of a superconducting qubit caused by a single quasiparticle. In our model, the qubit is an isolated system consisting of a small island (Cooper-pair box) and a larger superconductor (reservoir) connected with each other by a tunable Josephson junction. If such system contains an odd number of electrons, then even at lowest temperatures a single quasiparticle is present in the qubit. Tunneling of a quasiparticle between the reservoir and the Cooper-pair box results in the relaxation of the qubit. We derive master equations governing the evolution of the qubit coherences and populations. We find that the kinetics of the qubit can be characterized by two time scales - quasiparticle escape time from reservoir to the box, $Γ^{-1}_{in}$, and quasiparticle relaxation time $τ$. The former is determined by the dimensionless normal-state conductance $g_T$ of the Josephson junction and one-electron level spacing $δ_r$ in the reservoir ($Γ_{in}\sim g_Tδ_r$), and the latter is due to electron-phonon interaction. We find that phase coherence is damped on the time scale of $Γ^{-1}_{in}$. The qubit energy relaxation depends on the ratio of the two characteristic times, $τ$ and $Γ^{-1}_{in}$, and also on the ratio of temperature $T$ to the Josephson energy $E_J$.

cond-mat.mes-hall↗