Cavity-photon-switched coherent transient transport in a double quantum waveguide

Abstract

We study a cavity-photon-switched coherent electron transport in a symmetric double quantum waveguide. The waveguide system is weakly connected to two electron reservoirs, but strongly coupled to a single quantized photon cavity mode. A coupling window is placed between the waveguides to allow for electron interference or inter-waveguide transport. The transient electron transport in the system is investigated using a quantum master equation. We present a cavityphoton tunable semiconductor quantum waveguide implementation of an inverter quantum gate in which the output of the waveguide system may be selected via the selection of an appropriate photon number, or 'photon frequency' of the cavity. In addition, the importance of the photon polarization in the cavity that is either parallel or perpendicular to the direction of electron propagation in the waveguide system is demonstrated.

Electric-field control of bound states and optical spectrum in window-coupled quantum waveguides

“…Other frequently used shape of the common wall is a smooth Gaussian potential with a parabolic saddle-like dependence exp (−α 2 x x 2 − α 2 z z 2 ) in the coupling region. [24][25][26] Then, the inter-wire tunneling is determined not only by the opening size, which is defined as 2/α x , but by the barrier height too. Just this form of the potential was used to explain experimental data obtained from the split-gate structures.…”

“…If, after passing the opening, the charged particle propagates in the second wire only what is a logical state |1 , one has a realization of a quantum-NOT operation 19 and a situation when the electron wave is distributed equally between the guides corresponds to a square-root-of-NOT ( √ NOT) gate. Besides the CW size, which is the most crucial parameter in determining the switching rate, the latter can be additionally controlled by the external static perpendicular magnetic 16,18,25,26 or longitudinal electric 18 fields; by the surface acoustic waves; 21 by the optical radiation characterized by the photon number, frequency and polarization; 24,26 and by the Coulomb-like interaction between the electrons. 22,25,26 This was accompanied by in the case of the semiconductor DQW, is an electron effective mass in the corresponding material, e is the absolute value of the elementary charge, V (r) is electrostatic potential of the waveguides that is zero inside them and turns into infinity at the surfaces, and radiusvector r for the Q1D (3D) geometry is a function of the two (three) spatial coordinates: r = (x, z) [r = (x, y, z)].…”

Optical switching of electron transport in a waveguide-QED system

“…As we mentioned above, the pho- ton energy is smaller than the energy spacing between the first and the second subband of the waveguide system. In the presence of the photon cavity, photon replica states are formed and they actively participate in the electron transport [12]. For the case of an off-resonant photon field we choose the energy Ω γ = 0.5 meV, which is smaller than the electron confinement energy of the waveguide system in the y-direction ( Ω 0 = 1.0 meV).…”

“…1 and described in earlier work [11,12]. The left and right leads are coupled simultaneously smoothly within 20 ps to the waveguide system by the use of switching functions [13].…”

“…In addition, we reported the importance of the Coulomb interaction in * nzar.r.abdullah@gmail.com the electron switching [11,12]. In this work, we investigate the processes of electron switching in a coupled waveguide where a window coupling is placed between the waveguides.…”