There is tremendous potential for new information technology based on light (photons). Photons (light particles) are very well suited for carrying information and quantum technology based on photons -- called quantum photonics, will be able to hold much more information than current computer technology.
But in order to create a network with photons, you need a photon contact, a kind of transistor that can control the transport of photons in a circuit. Researchers at the Niels Bohr Institute in collaboration with researchers from the Korea Institute of Science and Technology have managed to create such a contact. The results are published in the scientific journal Nature Communications.
Quantum information can be sent optically, that is to say, using light, and the signal is comprised of photons, which is the smallest component (a quantum) of a light pulse. Quantum information is located in whichever path the photon is sent along -- it can, for example, be sent to the right or to the left on a semi-transparent mirror.
It can be compared to the use of bits made up of 0s and 1s in the world of conventional computers. But a quantum bit is more than a classical bit, since it is both a 0 and a 1 at the same time and it cannot be read without it being detected, as it is only a single photon. In addition, quantum technology can be used to store far more information than conventional computer technology, so the technology has much greater potential for future information technology.
Controlling the light
Light normally spreads in all directions. But in order to develop quantum technology based on light, you need to be able to control light down to the individual photons. Researchers in the Quantum Photonic research group at the Niels Bohr Institute are working on this and to do so, they use an optical chip embedded with a so-called quantum dot.
The optical chip is made up of an extremely small photonic crystal, which is 10 microns across (1 micron is a thousandth of a millimetre) and has a thickness of 160 nanometers (1 nanometer is a thousandth of a micron). Embedded in the middle of the chip is a so-called quantum dot, which is comprised of a collection of atoms.
"We have developed the photonic chip so that the quantum dot emits a single photon at a time and we can control the photon's direction. Our big new achievement is that we can use the quantum dot as a contact for the photons -- a kind of transistor. It is an important component for creating a complex network of photons," explains Peter Lodahl, professor and head of the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen.
'Gateway' for photons
The experiments are carried out in the research group's laboratories, which located in the basement of the Niels Bohr Institute so that there are no tremors from the road or disruptive ambient light.
They use a laser to produce the photons in the experiment. If the laser is fully dimmed, a single photon is released. If the intensity is increased, there is a greater chance of 2 or more photons at the same time. The number of photons is important for the result.
"If we send a single photon into the quantum dot, it will be thrown back -- the gateway is closed. But if we send two photons, the situation changes fundamentally -- the gateway is opened and the two photons become entangled and are sent onwards," explains Alisa Javadi, who is a postdoc in the research group and has worked with the experiments in the laboratory at the Niels Bohr Institute.
So the quantum dot works as a photon contact and this is an important component when you want to build complex quantum photonic circuits on a large scale.
Peter Lodahl Professor
Head of the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen
Associate Professor in the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen.
Postdoc in Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen.
Gertie Skaarup | EurekAlert!
European particle-accelerator community publishes the first industry compendium
26.04.2018 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP
Subnano lead particles show peculiar decay behavior
26.04.2018 | Ernst-Moritz-Arndt-Universität Greifswald
Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
26.04.2018 | Physics and Astronomy
26.04.2018 | Life Sciences
26.04.2018 | Medical Engineering