Prof Frank Vollmer

University of Exeter, Living Systems Institute

Exeter EX4 4QD, United Kingdom

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Quantum optical cavities for characterisation of single photon emitters as probes of biochemical activity and single-molecule lasers - PhD funded



Optical microcavities are important for many applications such as lasers, metrology and biosensing. Optical microcavities confine a light beam into a box, example for this is a Fabry-Perot cavity build by two opposing micro-mirrors. By adding a metal nanostructure to the box, the local light field can be dramatically enhanced, which potentially achieves the strong coupling between microcavity and single molecules. A light-driven metal nanoparticle exhibits the so-called localized surface plasmon resonance (LSPR), at which the electromagnetic (EM) field is confined with a region much smaller than the cube of light wavelength, exceeding the refraction limit. The resulting enhancement factor of the local EM field can be as high as 103. Placing a single-molecule quantum emitter within this region strongly raises the emitter-photon coupling strength as well as the sensitivity of a sensor. Such an optoplasmonic device composed of optical microcavity, plasmonic nanostructure and single molecule has been utilised for the single molecule sensing. In this project you will take the next step and develop the optoplasmonic approach to study the photons emitted by single molecules attached to the sensor. The resulting quantum optical probe for analysing single photons characteristics emitted from single-molecule biochemical activity has important applications in biosensing and for realising single-molecule lasers. Also, the techniques for analysing single-photon correlations and statistics have important applications in imaging.

Your Project


The project aims at the implementation and quantum optical characterization with optimized parameters of a single-biomolecule photon source for biochemical sensing, and imaging applications. Optoplasmonic Whispering Gallery Mode (WGM) optical cavities with very high quality factors will be designed and fabricated to realize the reliable and robust collection and characterisation of emitted single photons from single molecules. The study will also extend into the possible tuning and optimization schemes for the integrated sensing of biochemical activity at the single-photon and single molecule level, and approaching single-molecule laser device characteristics. The present experimental research project involves supporting theoretical studies for the design of optimized cavities and derivation of fundamentally new analysis of single photon correlations from single molecules operated in the lasing regime of an optoplasmonic sensor. Further, with the implementation of photon statistics analysis of the quantum optical single-molecule source, the project also explores novel approaches for quantum spectroscopy and imaging of chemical activity based on quantum-correlated-photon-based detection schemes.

What we are looking for


Well-motivated physics or engineering students with a passion for applied quantum optics and with a quantum optics background will be desirable for the present cutting-edge doctoral research project. The project is experimental but also has a strong theoretical component. You will work as part of a team of physicists, electrical engineers, and biochemists.