Chirality of nanophotonic waveguide with embedded quantum emitter for unidirectional spin transfer

TL;DR

This paper demonstrates that nanophotonic waveguides with embedded quantum dots can achieve unidirectional emission and spin-path conversion due to electromagnetic field chirality, enabling efficient quantum information transfer.

Contribution

It shows that chiral electromagnetic fields in nanophotonic waveguides induce unidirectional emission from quantum dots, with high spin-path conversion efficiency, despite non-chiral waveguide geometries.

Findings

Achieved deterministic positioning of quantum dots at chiral points.

Demonstrated up to 95% spin-path readout efficiency.

Compared nanobeam and photonic crystal waveguides, highlighting robustness of nanobeam design.

Abstract

Scalable quantum technologies require faithful conversion between matter qubits storing the quantum information and photonic qubits carrying the information in integrated circuits and waveguides. We demonstrate that the electromagnetic field chirality which arises in nanophotonic waveguides leads to unidirectional emission from an embedded quantum dot quantum emitter, with resultant in-plane transfer of matter-qubit (spin) information. The chiral behavior occurs despite the non-chiral geometry and material of the waveguides. Using dot registration techniques we achieve a quantum emitter deterministically positioned at a chiral point and realize spin-path conversion by design. We measure and compare the phenomena in single mode nanobeam and photonic crystal waveguides. The former is much more tolerant to dot position, exhibits experimental spin-path readout as high as 95 +/- 5% and has potential to serve as the basis of future spin-logic and network implementations.