A Resonant-Tunneling Quantum-Dot Demultiplexer for Scalable Cryogenic Single-Electron Routing

Abstract

Scaling quantum electronic systems such as quantum-dot spin qubits and single-electron devices is increasingly limited by the wiring overhead between cryogenic devices and room-temperature control electronics. Multi-channel quantum-dot architectures that selectively route electrons using a few shared control lines, analogous to demultiplexers in classical networks, offer a promising solution. Here, we propose and theoretically investigate a gate-defined architecture of three parallel quantum dots sharing a common source reservoir and coupled to independent drain channels. Using an analytical electrostatic model and tight-binding quantum transport simulations, we show that the device can act as an on-chip single-electron demultiplexer based on resonant tunneling in the cryogenic regime. Closed-system eigenstate analysis reveals localized orbital states in each dot, and open-system transport calculations show resonant conductance peaks when these levels align with the incident electron energy, consistent with the closed-system eigenenergy evolution. By engineering the barrier-gate spacing and the relative plunger-gate dimensions, we obtain well-separated resonances with minimal overlap between channels. Bond-current density calculations show that transport is confined to the resonant channel with negligible leakage into neighboring outputs, yielding channel selectivity approaching unity for all resonant modes. The architecture is compatible with Si/SiGe and GaAs/AlGaAs platforms and can be extended to more channels, offering a route toward programmable quantum routing and resonant-tunneling-based quantum circuitry.