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Colloidal Quantum Dot Quantum Optics

Periodic Reporting for period 4 - ColloQuantO (Colloidal Quantum Dot Quantum Optics)

Reporting period: 2020-11-01 to 2021-04-30

Over the last decades, there has been tremendous progress in the controlled fabrication of colloidal semiconductor nanocrystals. One of the potential applications of such structures is as sources for quantum states of light. During the past two and a half years we have made significant progress in constructing structures that function as very good single photo emitters at room temperature, and have been able to fabricate nanostructures that emit a small number of photons upon photoexcitation which almost always exceeds unity but rarely exceeds three. We are currently aiming for narrowing the distribution of the number of emitted photons from such structures, getting as close as we can to deterministic emitters of photon pairs. We are currently expanding these studies to low temperatures, aiming at generating quantum correlations between these photon pairs. All these will potentially function as future components in quantum devices.

Harnessing the ability to generate true single-photon emitters, we have demonstrated that this quantum resource can be used to enhance the spatial resolution in optical imaging. In particular, we have shown that the resolution of an optical microscope can be enhanced by up to four times better than the diffraction limit in a confocal setup harnessing single-photon emission. We are currently working on establishing this method as a general-purpose add-on to standard confocal microscopes both in terms of methods and in terms of hardware.
We have fabricated several new types of colloidal nanoparticles, mostly based on two-dimensional nanoplatelets, which should potentially exhibit intriguing nonclassical emission properties. One of the more unique features of such nanoplatelets we have already demonstrated, is the ability to imbue them with chiral properties, typically associated with external magnetic fields, simply via the use of organic linker molecules.
A more applicative aspect of quantum emission which we have been exploring is its application for sub-diffraction limited microscopy. We recently obtained the first quantum superresolved images of biological samples, and aim at developing this into a much more applicable method using state-of-the-art detectors and electronics.
By the end of the project we expect to achieve two goals. The first is to develop new quantum light sources as future components in quantum devices. The second is to perform new types of quantum spectroscopy, which will help in elucidating the photophysics of quantum confined particles at low temperatures.
Beyond this, we hope to be able to develop a prototype detector/electronics combination for use in quantum superresolved imaging.
Comparison of a standard confocal image (left) with a quantum enhanced image (right)