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Scientists manipulate the properties of quantum dots



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Scientists at MEPhI National Research Nuclear University (MEPhI) have demonstrated an increase in the emission intensity and rate of quantum dots. According to the study̵

7;s authors, development could help solve one of the key problems in creating a quantum computer and take biomedical surveillance to the next level. The research results have been published above Optics Express.


Quantum dot is a low-dimensional fluorescent nanostructure that holds promise in the field of light matter interactions. They are capable of absorbing a lot of light and emitting light of a narrow wavelength, depending on the size of the nanocrystals; that is, one or another quantum dot glowing with a certain color. These properties make quantum dots almost perfect for the super-sensitive multi-color registration of biological objects, as well as for medical diagnostics.

Quantum dots can be used in a variety of fields, from lighting devices and solar panels to qubits for quantum computing. They are better than traditional phosphorus in terms of optical stability and brightness. Quantum dot displays can offer higher brightness, contrast, and much lower power consumption than other technologies.

Researchers at the Nano Biotechnology Laboratory (LNBE) of the Institute of Biomedical Engineering Physics, MEPhI, were the first to demonstrate the increase in both spontaneous emission intensity and rate of dots. semiconductor quantum in a silicon-based porous photon structure.

The results of the study represent a new approach to controlling spontaneous light emission by altering the local electromagnetic environment of phosphorus in a porous matrix, opening up prospects for new applications in biological sensors, optoelectronics, cryptography and quantum computing.

First, the new systems can form the basis for compact fluorescent biosensors in the form of enzyme-linked immunosorption assays, widely available in clinical practice. Using quantum dots with photonic crystal-enhanced fluorescence significantly increases analytical sensitivity, helping to detect disease early, when the number of pathological markers in the patient’s blood is low. It will also facilitate the monitoring of the patient’s treatment.

Furthermore, this development could serve as the basis for an optical computer or cryptosystem, replacing cumbersome sources containing single photons or optical logic elements. In addition to their compactness and simplicity, the use of new systems in the field will allow to solve one of the industry’s key problems: on-demand production of single photons or quantum entanglement, which is almost not present at present.

Entangled photons – a pair of particles in a correlated quantum state – play an important role in modern physics. Without entangled pairs, it is almost impossible to perform quantum communication and quantum displacement, and to build quantum computers connected to the quantum Internet. If quantum computers were created, the principles of whole domains – molecular models, cryptography, artificial intelligence – could change completely.

The MEPhI scientists obtained this result by using the deep oxidation of photonic crystals, which prevents luminescence quenching, as well as reduces energy loss for the absorption process.

“To enhance the luminescence of such structures, a variety of methods are used, of particular interest in using photonic crystals. Periodic variation in the refractive index of photonic crystals.” making it possible to achieve a local increase in the photonic state density, thus the phosphorus Pavel Samokhvalov, researcher at LNBE MEPhI, said ‘intensity and increase in spontaneous emission rate observed.

In the manufacture of photonic crystals, porous silicon is widely used, different from other materials due to its precise control of the refractive index, ease of fabrication and absorption.

So far, however, researchers have not been able to increase the rate of phosphorus radiation expansion in porous silicon photonic crystals due to significant luminescent quenching when exposed to silicon surfaces.


Scientists create new equipment to pave the way for quantum technology


More information:
Dmitriy Dovzhenko et al. Enhance spontaneous emission of semiconductor quantum dots inside the one-dimensional porous silicon photonic crystal Optics Express (Year 2020). DOI: 10.1364 / OE.401197

Provided by National Research Nuclear University

Quote: Scientists manipulate the properties of quantum dots (2020, November 4) retrieved November 4, 2020 from https://phys.org/news/2020-11-scientists-properties- quantum-dots.html

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