17 March 2014 Hyperentanglement

Bragg reflection waveguide structure considered to generate hyperentangled paired photons correlated in polarization, spatial mode and frequency.

Generating a zoo of hyperentangled photons in semiconductor waveguides. In the recent study “Hyperentangled photon sources in semiconductor waveguides”, researchers have proposed and analyzed the performance of semiconductor’s waveguides to generate hyperentangled photons in polarization, spatial modes and frequency. The scientific results, fruit of an international collaboration with participation of the Quantum engineering of light Research Group led by UPC Prof at ICFO Juan P. Torres, have been published in Physical Review A, and have been chosen by the editors as Editors’s suggestion.

Paired photons that are entangled in multiple degrees of freedom (DOFs), or hyperentangled, have attracted a lot of interest in recent years, since they offer significant advantages in quantum information processing, in particular in tasks such as superdense coding, multidimensional quantum cryptography, and the efficient construction of cluster states.

By using monolithic semiconductor waveguides and two concurrent type-II spontaneous parametric down-conversion (SPDC) processes, where photons were cross-polarized and guided by different guiding mechanisms, the researchers showed that it was possible to generate paired photons which acquired entanglement in polarization, spatial modes and frequency, or even in a single degree of freedom optionally. Such a unique feature, which opens a pathway to generate hyperentanglement in integrated semiconductor platforms, might well provide extra control over the properties of the hyperentangled photons.