Mesoscopic effects in tunneling between parallel quantum wires

Abstract

We consider a phase-coherent system of two parallel quantum wires that are coupled via a tunneling barrier of finite length. The usual perturbative treatment of tunneling fails in this case, even in the diffusive limit, once the length L of the coupling region exceeds a characteristic length scale Lt set by tunneling. Exact solution of the scattering problem posed by the extended tunneling barrier allows us to compute tunneling conductances as a function of applied voltage and magnetic field. We take into account charging effects in the quantum wires due to applied voltages and find that these are important for one-dimensional-to-one-dimensional tunneling transport. PACS number(s): 73.63. Nm, 73.40.Gk

Probing spin-charge separation in tunnel-coupled parallel quantum wires

“…This is seen, e.g., in Fig. 1 where we show the result for the band-shifting limit 13 where applied voltages are assumed to shift electron bands without filling them: ν U = ν L = 1. The slopes of bright maxima are given by the inverse of the charge and spin velocities.…”

“…In the absence of interactions, this scale is given by the tunneling strength |t|, and the regime where perturbation theory fails is characterized by spatial and temporal oscillations in electronic correlation functions. 13 These oscillations result from coherent electron motion between the two systems. 19 In Sec.…”

“…The possibility to tune canonical versus kinetic momentum by an external magnetic field makes it possible to perform momentum-resolved tunneling studies. 12 For example, in a 1D Fermi liquid, resonances appear in the magnetic-field dependence of the linear tunneling conductance whenever Fermi points from different wires overlap, 13,14 i.e., when for any α, α ′ = ± the parameter…”

Collective excitation of quantum wires and effect of spin-orbit coupling in the presence of a magnetic field along the wire

“…Wavenumber selectivity due to momentum-resolved tunneling between them, E − (k) = E(k), allows a mapping of the dispersion 15,16,19 . Even in the presence of electron interactions this technique allows direct measurement of the collective excitation spectrum.…”

“…11,12,13,14 We suggest that the measurement of the velocity of the collective excitation v 0 may provide another way to determine the value of η R . This measurement can be carried out using tunneling between two parallel wires in the presence of an additional magnetic field B t = ∇ × A t along the y-axis 15,16 . This method allows one to determine the spectrum of elementary excitations 17,18 momenta much larger than 2k F 19 .…”