Controlled coupling of spin-resolved quantum Hall edge states

We introduce and experimentally demonstrate a new method that allows us to controllably couple co-propagating spin-resolved edge states of a two dimensional electron gas (2DEG) in the integer quantum Hall regime. The scheme exploits a spatially-periodic in-plane magnetic field created by an array of cobalt nano-magnets placed at the boundary of the 2DEG. A maximum charge/spin transfer of 28 ± 1% is achieved at 250 mK. This advancement addresses a critical challenge in implementing coherent electronics circuitry and quantum-computation architectures by enabling the precise control of charge transfer between co-propagating edge states, thus facilitating the realization of one-qubit gate transformations in proposed devices. The findings indicate that these spin-resolved edge states, characterized by their large relaxation and coherence lengths, can be manipulated through artificial magnetic fields, providing a pathway to potential applications in quantum information technologies.