Aperiodic geometries for quantum technology applications

In this project, we aim at using aperiodic patterns, described by Fibonacci series, to create functional quantum photonic devices. These aperiodic structures will allow controlling the propagation of light and the realisation of novel single-photon sources. Our proof-of-principle results have shown that aperiodic structures can be used to enhance the light-matter interaction on a chip, thus opening the path to the development of quantum devices.

Examples of confined optical modes in aperiodic suspended GaAs membranes containing quantum dots (Fig.1) are shown in Fig. 2: via photoluminescence imaging, we can visualise the annular-shaped photonic modes and address them individually. With this project, we will show that the efficient two-dimensional light confinement and the Purcell enhancement that we have demonstrated can be utilized for the development of novel single-photon devices where optical angular momentum, that can be used as an additional degree of freedom to encode information, is imparted to the emitted radiation.

The student will fabricate quantum photonic devices embedding positioned single quantum dots. Our previous work featured relatively high densities of emitters so as to be able to map the different localised modes (see Fig. 2): here, we will realise devices with single InAs/GaAs quantum dots. The emitters will be positioned such that their oscillating dipoles overlap with the maximum of the electromagnetic field of specific aperiodic photonic modes, using the positioning technique that we have developed.

In this way, we will maximise the light-matter interaction and enhance the spontaneous emission rate of single emitters, thus improving the brightness and coherence of the single-photon emission. As theoretically predicted, we will show that optical angular momentum can be imparted to the emitted single photons, thus allowing access to a further degree of freedom for storing information for quantum information technology applications.