Past events

Semiconductor devices for quantum technologies

Prof. Jonathan Finley, Technische Universität München (TUM) 

Part of the Zepler Institute Quantum Science Distinguished Lecture Series


The application of ultrafast optical techniques to probe and manipulate discrete quantum states in solids benefits from the possibility to apply established methods from quantum optics such as coherent control, optical pumping, resonant light scattering and dynamical decoupling. Moreover, such all-optical approaches open the way to inter-connect different quantum systems via photonic channels in integrated architectures. In this talk, we will explore several research themes pursued in my group in which individual, optically active semiconductor quantum dots are embedded within electrically tunable, tailored photonic nano-materials and addressed via resonant and near-resonant optical pulses. For example, we have applied multicolour ultrafast pump-probe spectroscopy to study coherent exciton and electron spin dynamics over timescales ranging from a few picoseconds up to ~10µs. Results show how the polarisation state of light can be faithfully mapped onto the exciton or electron spin, manipulated via geometric phase control and read out via spin-selective stimulated exciton emission, conditional biexciton absorption or via spin-charge conversion and luminescence recycling. By blue-detuning the laser pulse from the excitonic transitions we demonstrate how dissipation arising from exciton-LA phonon interactions can be used for high fidelity state preparation and measure the spectral function of the exciton-phonon coupling.  

We will continue to discuss how slow light phenomena in GaAs photonic crystal waveguides can be used to efficiently route single photons and illustrate how one can detect light on-chip using integrated NbN superconducting single photon detectors (SSPDs) on GaAs substrates. We observe the on-chip generation of the emission from resonantly excited individual quantum dots, efficient routing over lengthscales ≥1 mm via multi-mode GaAs ridge waveguides and sensitive in-situ detection using evanescently coupled integrated NbN superconducting single photon detectors fabricated on the same chip. By temporally filtering the time-resolved luminescence signal stemming from single, resonantly excited quantum dots we use the prototypical quantum optical circuit to perform time resolved excitation spectroscopy on single dots and demonstrate resonant fluorescence with a narrow linewidth of <10µeV; key elements needed for the use of single photons in prototype quantum photonic circuits. 


Jonathan Finley obtained a Ph.D. in experimental physics in December 1998 at the University of Sheffield, U.K. working under the guidance of Prof. M. S. Skolnick (FRS).  His PhD research focused on the use of optical spectroscopic techniques to probe fundamental physical, electronic, optical and quantum processes in III-V semiconductors and their associated nanostructures. After graduation, a Royal Society Research Fellowship took him to the Technical University of Munich where he worked as a postdoctoral fellow (1998-2000) with Prof. Dr. Gerhard Abstreiter at the Walter Schottky Institut ( During that period he pioneered the development of quantum dot (QD) memory structures that allow optically induced single charge preparation and readout in InAs and Ge QDs and their electrical or optical detection. This project laid the foundation for the later experimental demonstrations that spin relaxation mediated by spin-orbit interactions is strongly suppressed in quantum dots for both electrons and holes, work for which he was awarded the Walter Schottky Prize of the German Physical Society (DPG) in 2007 and the ISCS Young Scientist Prize in 2008.

In late 1999 J. J. Finley returned to the United Kingdom as a research Fellow at the University of Sheffield where his attention shifted to optical spectroscopy of single quantum dots using low temperature confocal microscopy. Thereafter, he returned to TUM in 2002 where, after brief tenure as a Max Planck Research Fellow at the Max Planck Institut für Quantenoptik he was appointed professor for Nanostructure Physics in the Physics Department and Walter Schottky Institut in December 2002, receiving tenure in 2007 and being promoted to full professor in 2013. Prof. Finley’s research interests focus on the development and exploitation of emergent semiconductor materials for quantum technologies, quantum optics of semiconductor nanostructures and nano-photonics including photonic crystal nanostructures. Jonathan Finley is author of > 260 research manuscripts, book chapters and review articles that have been cited more than 5000 times (h-index=34, i10-index=75).

All are welcome to attend. Please reserve your place using the button on the right of this page. Tea and cakes will be served before the lecture from 16:30.