Fano resonance in a quantum wire with a side-coupled quantum dot

Abstract

We report a transport experiment on the Fano effect in a quantum connecting wire (QW) with a side-coupled quantum dot (QD). The Fano resonance occurs between the QD and the "T-shaped" junction in the wire, and the transport detects antiresonance or a forward scattered part of the wave function. While it is more difficult to tune the shape of the resonance in this geometry than in the previously reported Aharonov-Bohm-ring-type interferometer, the resonance purely consists of the coherent part of transport. Utilizing this advantage, we have quantitatively analyzed the temperature dependence of the Fano effect by including the thermal broadening and the decoherence. We have also proven that this geometry can be a useful interferometer for measuring the phase evolution of electrons at a QD.

Excited-state spectroscopy on a quantum dot side coupled to a quantum wire

“…However in the application to quantum information processing, the number of leads is desired to be as small as possible, because the connection to the outside circuits brings in quantum decoherence. Besides the decoherence, a dot with a single-lead has a number of advantages such as the spatial compactness, the easiness to go down to the few electron regime [3], and so on.In single-lead dots, the spectroscopic information is usually given through the interference (the Fano effect) [4,5] or the charge detection [6]. However, these measurements were limited to the spectroscopy of the ground states.…”

“…In single-lead dots, the spectroscopic information is usually given through the interference (the Fano effect) [4,5] or the charge detection [6]. However, these measurements were limited to the spectroscopy of the ground states.…”

Equivalence of the effective Hamiltonian approach and the Siegert boundary condition for resonant states

“…Quantum resonance, in particular, has been a central issue of quantum mechanics from the early days of its development [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. It is ever more important these days because we can closely observe and even manipulate quantum-mechanical systems such as mesoscopic systems, molecules and nuclides [16][17][18][19][20][21]: for example, the resonant conduction in experiments of mesoscopic systems yields a variety of functions of nano-devices; producing unstable nuclides experimentally is nothing but looking for resonant states. It may be said, however, that such experimental studies on quantum resonance far surpass theoretical ones.…”

Quantum electron splitter based on two quantum dots attached to leads

“…2 In addition, Fano resonances have been clearly observed in a quantum wire ͑QW͒ with a sidecoupled QD, and it has been proven that this geometry can be used as an accurate interferometer. 3,4 More recently, we have considered electron transport in a double QD side attached to a QW by means of the two impurity Anderson Hamiltonian. 5 The conductance was found to be a superposition of Fano and Breit-Wigner resonances as a function of the Fermi energy, provided the gate voltages of the QDs were slightly different.…”