Dr Hamid Ohadi

Project Title: Optical trapping of nanoparticles in fibre microcavities

Exploiting the laws of quantum mechanics for the benefit of humanity in the so-called “second quantum revolution” is one of the greatest challenges of the 21st century. For this we need to efficiently produce particles, control their states, detect them and make them interact strongly at the single-particle level. Photons, the quantum particles of light, are one of the most promising candidates. We can easily detect and control their states and we can efficiently produce them individually. However, making them interact strongly to build a large quantum network is a notoriously difficult task because photons do not interact at low energies. To make them interact indirectly, one can hybridise them with other massive particles that strongly interact and form new particles called ‘polaritons’.

In the “Quantum Fluids of Light” group in St Andrews, we aim to hybridise photons with different types of matter to make polaritons. To bring photons to interact with matter, we confine them in between two opposing reflective mirrors. The light will bounce between them many times. These two reflective mirrors form a “cavity”.  Inside this cavity we place a thin layer of matter, typically a semiconductor. The photons bouncing between the mirrors get absorbed by the particles in the semiconductor and reemit back into the cavity. The matter particles can interact with each other, through which the photons can also interact with each other. If the indirect interaction between the photons is large enough, the quantum effects can be harnessed for making new devices and CPUs that can surpass our current technologies in terms of efficiency and speed.

This research topic has been funded by a few grants including a Carnegie Research Grant, an EPSRC New Investigator Award and a Royal Society research grant.