Scientists from the Swiss Nanoscience Institute and the University of Basel have succeeded in coupling an extremely small quantum dot with 1,000 times larger trumpet-shaped nanowire. The movement of the nanowire can be detected with a sensitivity of 100 femtometers via the wavelength of the light emitted by the quantum dot. Conversely, the oscillation of the nanowire can be influenced by excitation of the quantum dot with a laser. Nature Communications published the results.
Professor Richard Warburton and Argovia Professor Martino Poggio's teams in the Department of Physics and the Swiss Nanoscience Institute at the University of Basel worked with colleagues from Grenoble Alps University and the Alternative Energies and Atomic Energy Commission (CEA) in Grenoble to couple a microscopic mechanical resonator with a nano-scale quantum dot. They used nanowires made of gallium arsenide that are about 10 micrometers long and have a diameter of a few micrometers at the top. The wires taper sharply downwards and therefore look like tiny trumpets arranged on the substrate. Near the base, which is only about 200 nanometers wide, the scientists placed a single quantum dot that can emit individual light particles (photons).
Trumpet-shaped nanowires with a length of about 10 micrometers are coupled to quantum dots located at their bases. The movement of the nanowire can be detected with a sensitivity of 100 femtometers by changing the wavelength of the light emitted by the quantum dots. The arrows are important for fabrication and help to locate the nanowires.
Credit: Grenoble Alps University
Excitations lead to strains
If the nanowire oscillates back and forth due to thermal or electrical excitation, the relatively large mass at the wide end of the nano-trumpet produces large strains in the wire that affect the quantum dot at the base. The quantum dots are squeezed together and pulled apart; as a result, the wavelength and thus the color of the photons emitted by the quantum dot change. Although the changes are not particularly large, sensitive microscopes with very stable lasers - specifically developed in Basel for such measurements - are capable of precise detection of the wavelength changes. The researchers can use the shifted wavelengths to detect the motion of the wire with a sensitivity of only 100 femtometers. They expect that by exciting the quantum dot with a laser, the oscillation of the nanowire can be increased or decreased as desired.
Potential uses in sensor and information technology
"We are particularly fascinated by the fact that a link between objects of such different sizes is possible," says Warburton. There are also various potential applications for this mutual coupling. "For example, we can use these coupled nanowires as sensitive sensors to analyze electrical or magnetic fields," explains Poggio, who is investigating the possible applications with his team. "It may also be possible to place several quantum dots on the nanowire, to use the motion to link them together and so pass on quantum information," adds Warburton, whose group focuses on the diverse use of quantum dots in photonics.
Artificial atoms with special properties
Quantum dots are nanocrystals, and are also known as artificial atoms because they behave similarly to atoms. With a typical extent of 10 to 100 nanometers, they are significantly larger than actual atoms. Their size and shape, as well as the number of electrons, can vary. The electrons' freedom of movement in the quantum dots is significantly restricted; the resulting quantum effects give them very special optical, magnetic and electrical properties. For example, quantum dots are able to emit individual light particles (photons) after excitation, which can then be detected using a tailor-made laser microscope.
Mathieu Munsch, Andreas V. Kuhlmann, Davide Cadeddu, Jean-Michel
Gérard, Julien Claudon, Martino Poggio, and Richard J. Warburton
Resonant driving of a single photon emitter embedded in a mechanical oscillator
Nature Communications (2017) | DOI: s41467-017-00097-3
Olivia Poisson | EurekAlert!
CCNY physicists master unexplored electron property
26.07.2017 | City College of New York
Large, distant comets more common than previously thought
26.07.2017 | University of Maryland
Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers
Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...
Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.
At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
26.07.2017 | Event News
21.07.2017 | Event News
19.07.2017 | Event News
26.07.2017 | Physics and Astronomy
26.07.2017 | Life Sciences
26.07.2017 | Earth Sciences