A new spin on light manipulation

One of the most important and uniquely quantum properties of elementary particles is spin. This intrinsic angular momentum is unrelated to moving parts, it is quantised (has only certain discrete values) and, in the case of photons, it can be polarised or essentially aligned in a certain direction.

The quantum properties of a quantum of light, the photon, are opening the doors to amazing new devices until recently the stuff of science fiction. Spin-optronics is in an important and emerging new field that studies spin and optical polarisation in solids with the goal of creating quantum optoelectronic devices. Ten leading European teams joined forces to prepare a new generation of scientists in this strategic research area with EU funding of the project 'Spin effects for quantum optoelectronics' (SPIN-OPTRONICS).

The 18 early-stage and experienced researchers conducted cutting-edge research in 4 main areas under the guidance and mentoring of SPIN-OPTRONICS partners. Groundbreaking results were achieved in all areas.

Reversible control of single spins is of great interest for development of spintronics devices. The researchers successfully addressed the main challenges associated with control of single spins in quantum dot devices and demonstrated that control in several different systems.

Scientists also developed semiconductor entangled light-emitting diodes (ELEDs). Quantum entanglement occurs when the quantum state of one particle is dependent on that of another. The ELEDs were used in groundbreaking experiments related to quantum information processing and quantum-based secure communication (quantum key distribution).

Spin interactions and magnetic effects were also explored, leading to fabrication of a new class of hybrid spin-optronic heterostructures. The project would not be complete without delivery of actual functioning devices. Scientists developed several polariton-based circuits (tunnel diodes, interferometers, switches) exploiting novel hybrid particles consisting of photons strongly coupled to an electric dipole. The project has also demonstrated that the polariton flows can support the propagation of superfluid spin currents and of magnetic charge analogs, moving close to the speed of light and being therefore a very promising vector for the ultrafast transfer and processing of information.

The SPIN-OPTRONICS training network has pushed the frontiers of an emerging new field whose potential for future commercial exploitation is huge. Establishing world leadership with a core group of European researchers will pave the way to important benefits for the EU and its economy in a time of severe economic crisis.