The approach used by the researchers is based on a micro-ring resonator - a tiny optical cavity - in which energy conservation constraints can be exploited to suppress classical effects while amplifying quantum processes.
They used laser beams at different wavelengths and then had to overcome the risk of the two pump beams being able to destroy the photons' fragile quantum state.
Prof Moss said: “While a similar suppression of classical effects has been observed in gas vapours and complex micro-structured fibres, this is the first time it has been reported on a chip, opening a route for building scalable integrated devices that exploit the mixing of polarisation on a single photon level.
"It also has the advantage that the fabrication process of the chip is compatible with that currently used for electronic chips which not only allows the exploitation of the huge global infrastructure of CMOS foundries, but will ultimately offer the potential to integrate electronic devices on the same chip,” he concluded.
