Abstract
Precise shaping of coherent electron sources allows the controlled creation of wavepackets into a one dimensional (1D) quantum conductor. Periodic trains of Lorentzian pulses have been shown to induce minimal excitations without creating additional electron–hole pairs in a single non-interacting 1D electron channel. The presence of electron–electron (e–e) interactions dramatically affects the non-equilibrium dynamics of a 1D system. Here, we consider the intrinsic spectral properties of a helical liquid, with a pair of counterpropagating interacting channels, in the presence of time-dependent Lorentzian voltage pulses. We show that peculiar asymmetries in the behavior of the spectral function are induced by interactions, depending on the sign of the injected charges. Moreover, we discuss the robustness of the concept of minimal excitations in the presence of interactions, where the link with excess noise is no more straightforward. Finally, we propose a scanning tunneling microscope setup to spectroscopically access and probe the non-equilibrium behavior induced by the voltage drive and e–e interactions. This allows a diagnosis of fractional charges in a correlated quantum spin Hall liquid in the presence of time-dependent drives.
Highlights
Recent advances in mesoscopic physics allowed to study new quantum effects and their potential for storing, controlling, and manipulating quantum information in a precise and robust fashion [1,2,3,4]
We focus on the injection of integer Levitons, the cleanest signal in non-interacting systems, in order to better enlighten interaction induced effects. In this non-equilibrium situation, peculiar charge asymmetries are visible in the spectral function, but they can be masked in a conventional excess noise experiment
In order to better elucidate the effects induced by e-e interactions, we have focused on the case of a periodic train of integer Lorentzian pulses, which is known to generate minimal excitations in a 1D free-fermion system
Summary
Recent advances in mesoscopic physics allowed to study new quantum effects and their potential for storing, controlling, and manipulating quantum information in a precise and robust fashion [1,2,3,4]. Systems with topological properties, such as the integer and fractional quantum Hall [5,6,7] and topological insulators [8,9,10,11,12,13], played a prominent role due to their intrinsic robustness against disorder and decoherence. We consider a pair of counterpropagating helical channels, subject to a time-dependent drive, where a richer phenomenology arises compared to more conventional single-channel and spinless conductors This scenario naturally raises the question: how electron-electron interactions affect the dynamics of injected wavepackets and Levitons in helical channels?
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