The high current density required for population inversion in organic semiconductors has made the realization of an organic laser diode rather challenging. Here, I propose an organic polariton laser diode (OPLD) in which the threshold is achieved through the mechanism of polariton condensation. This conceptually different lasing mechanism does not require population inversion, suggesting that lasing under electrical injection can be, for the first time, demonstrated in organic semiconductors. To date, most commercial laser diodes are based on inorganic semiconductors, which are expensive materials, require complex fabrication and manufacturing processes, and have a limited range of lasing wavelengths. Organic semiconductors, in contrast, are ideal materials for the industrial production of diode lasers and other optoelectronic devices due to their ease of fabrication and processing, low acquisition-cost, and broad spectrum of emission. The realization of the first OPLD within this fellowship will be tremendously important for the European market. In 2014, diode-laser technology comprised 46% of the total revenue ($9.4 billion) in the global laser market. Moreover, emerging automotive lighting (BMW Laserlight) and high-definition laser display (LG LASER display) technologies could enable diode lasers to overtake the global laser market. Therefore, any steps towards the realization of the first organic laser diode (or organic solid state laser) would represent a significant technological and scientific achievement. Furthermore, the proposed device offers a totally new, due to its electrical pumping, platform for fundamental studies of quantum fluids of light.

Molecular structure determination is vital for biochemistry, life science, and drug industry. A complete determination of the molecular structure requires both the structural skeleton and atoms therein to be identified. Non-contact Atomic Force Microscopy provided a method to image the real-space structural skeleton of planar organic molecule, however, the chemical identities of each atom that comprise the molecule are yet to be determined. In this proposal, I systematically analyze the physical principle for elemental identification in single molecules and propose a practical method to identify each atom using point spectrum with non-contact atomic force microscope.

Since Richard Feynman's famous talk There is Plenty of Room at the Bottom in 1959, the following decades saw the booming of nanotechnology. One of the fields in which nanotechnology can never be ignored is the development of scientific instruments. Scientific instruments based on nanotechnology have revolutionized many research fields. However, using current instruments to study superfluid He is still challenging, especially for the topological defects (TDs) and topological matter (TM) because the scale of the coherence length of the interesting objects in 3He is just tens of nanometers. The N2PCON (Nanostructures and Nanoelectromechanical devices for Precise CONtrol of topological defects/matter in superfluid He) project will offer a nanotechnology solution to precisely control and study TDs and TM. In this action, I will work in the OtaNano (Finnish national infrastructure for nanoscience and nanotechnology) at Aalto University, with the supervision of Dr. Sami Franssila (Department of Chemistry and Materials Science) and Dr. Vladimir Eltsov (Department of Applied Physics). At the same time, I will also work with my secondment institutes, Royal Holloway, University of London, UK and Lancaster University, UK, to boost this action. The action will produce nanoscale instruments (NEMS, nanostructures) that surpass the current state-of-the-art devices, in both performance and dimension, to reach the quantum world of TDs and TM. N2PCON is expected to provide new tools for superfluid research and also add general knowledge to MEMS/NEMS and cosmology. In the long term, it will boost the MEMS/NEMS research and industry in the EU.

Real-world optimization problems pose major challenges to algorithmic research. For instance, (i) many important problems are believed to be intractable (i.e. NP-hard) and (ii) with the growth of data size, modern applications often require a decision making under {\em incomplete and dynamically changing input data}. After several decades of research, central problems in these domains have remained poorly understood (e.g. Is there an asymptotically most efficient binary search trees?) Existing algorithmic techniques either reach their limitation or are inherently tailored to special cases. This project attempts to untangle this gap in the state of the art and seeks new interplay across multiple areas of algorithms, such as approximation algorithms, online algorithms, fixed-parameter tractable (FPT) algorithms, exponential time algorithms, and data structures. We propose new directions from the {\em structural perspectives} that connect the aforementioned algorithmic problems to basic questions in combinatorics. Our approaches fall into one of the three broad schemes: (i) new structural theory, (ii) intermediate problems, and (iii) transfer of techniques. These directions partially build on the PI's successes in resolving more than ten classical problems in this context. Resolving the proposed problems will likely revolutionize our understanding about algorithms and data structures and potentially unify techniques in multiple algorithmic regimes. Any progress is, in fact, already a significant contribution to the algorithms community. We suggest concrete intermediate goals that are of independent interest and have lower risks, so they are suitable for Ph.D students.

Swimming is ubiquitous in nature and crucial for the survival of a wide range of organisms. Many swimmers move together in intricate swarms, widely believed to save energy through collective hydrodynamic interactions. While the physics behind swimming and swarming of viscosity-dominated microswimmers and inertia-dominated macroswimmers has been extensively studied, little is known about the intermediate regime (~ 0.1–10 cm), where both viscous and inertial forces are important. This mesoscale is full of living organisms, such as small larvae, shrimps, and jellyfish, and the physics behind their swimming and swarming is strongly complicated by non-linear and time-dependent effects at increasing swimming speeds and organism sizes. A breakthrough in our understanding of mesoscale swarming dynamics is hindered by an absence of force-based experiments on collective mesoswimming. Here, I will perform pioneering experiments on the swimming forces of brine shrimps as model organisms. I aim to discover how they adapt their motility in different environments and perform the first direct measurements on the binary and many-body swimming and hydrodynamic interaction forces within pairs and small swarms of brine shrimps. I aim to resolve several major questions on mesoscale motility and swimming interactions, with the grand goal to discover new insights into how and why swarms of mesoswimmers are formed in nature. My experiments will open a new living matter physics research avenue at the mesoscale, and provide sensitive and important force and fluid dynamics data for theorists to use in their future models and for engineers to use in their biomimicry design of new mesorobots. The indirect impact of my work is the creation of new biomedical and engineering applications at the mesoscale, such as swallowable surgery with swarming mesorobots capable of optimising their swarm geometry to minimise power consumption in different environments.