Interactions and Charge Fractionalization in an Electronic Hong-Ou-Mandel Interferometer

Abstract

We consider an electronic analog of the Hong-Ou-Mandel (HOM) interferometer, where two single electrons travel along opposite chiral edge states and collide at a quantum point contact. Studying the current noise, we show that because of interactions between copropagating edge states, the degree of indistinguishability between the two electron wave packets is dramatically reduced, leading to reduced contrast for the HOM signal. This decoherence phenomenon strongly depends on the energy resolution of the packets. Insofar as interactions cause charge fractionalization, we show that charge and neutral modes interfere with each other, leading to satellite dips or peaks in the current noise. Our calculations explain recent experimental results [E. Bocquillon Science 339 1054 (2013)] where an electronic HOM signal with reduced contrast was observed.

Time-resolved pure spin fractionalization and spin-charge separation in helical Luttinger liquid based devices

“…Injection can be achieved by, e.g., applying a voltage pulse to the injection gate, while quantum point contacts can be exploited to perform time-resolved detection [11,39,[43][44][45][46]. Crucially, the concept of electron wave packet makes sense in the FL region only: after entering the interacting region, the electron wave packet is decomposed into charge and spin collective excitations, governed by the equations of motion [5,6,47]…”

Time-resolved energy dynamics after single electron injection into an interacting helical liquid

“…In this regard, it is worth mentioning two seminal experiments, based on the chiral edge state of a ν = 2 quantum Hall system, dealing with the socalled Hanbury-Brown-Twiss [28] and the Hong-Ou-Mandel [29] effects. Different theoretical works have investigated single electron injection in chiral conductors [18,22,23] and the role of e-e interactions in copropagating edge channels [30][31][32][33][34], aiming at an explanation of recent experimental observations. In addition, heat and energy transport have also been considered [35][36][37] in the presence of external drive, but only in the absence of e-e interactions.…”

“…These features allow for a richer phenomenology, in comparison with quantum Hall-based setups [46,47], and for the study of effects related to spin entanglement [48][49][50], relevant for quantum computation implementations. In this context, e-e interactions between counterpropagating edge channels can lead to remarkable effects, also in comparison with the case of interacting copropagating edge states of chiral conductors [30][31][32][33][34]. A deep understanding of the role of interactions is thus of great importance in view of all these realizations.…”

Resonant Edge Magnetoplasmons and Their Decay in Graphene

“…ECs support collective excitations called edge magnetoplasmons (EMPs) [5,6], which form the bosonic modes in a Tomonaga-Luttinger liquid representation [7]. EMPs lead to charge fractionalization [8,9] and their dissipation causes energy relaxation [10,11] and decoherence [4,12,13] in ECs. To better understand these physics and to obtain robust quantum effects, investigation of EMP decay mechanism is essential.…”