Electronic circuits are based on electrons, but one of the most promising technologies for future quantum circuits are photonic circuits, i.e. circuits based on light (photons) instead of electrons.
First, it is necessary to be able to create a stream of single photons and control their direction. Researchers around the world have made all sorts of attempts to achieve this control, but now scientists at the Niels Bohr Institute have succeeded in creating a steady stream of photons emitted one at a time and in a particular direction. The breakthrough has been published in the scientific journal Physical Review Letters.
This is an illustration of the single-photon cannon. A quantum dot (illustrated with the yellow symbol) emits one photon (red wave packet) at a time. The quantum dot is embedded in a photonic-crystal structure, which is obtained by etching holes (black circles) in a semiconducting material (light grey). Due to the holes, the photons are not emitted in all directions, but only along the channel where there are no holes. Only 1.6 percent of the emitted photons will be emitted in other directions (illustrated by the upward moving photon) and is thus lost, while 98.4 percent are emitted in the desired direction.
Credit: Illustration: Marta Arcari, Niels Bohr Institute
Photons and electrons behave very differently at the quantum level. A quantum is the smallest unit in the atomic world and photons are the basic units of light and electrons of electrical current. Electrons are so-called fermions and can easily flow individually, while photons are bosons that prefer to clump together. But because information for quantum communication based on photonics lies in the individual photon, it is necessary to be able to send them one at a time.
"So you need to emit the photons from a fermionic system and we do this by creating an extremely strong interaction between light and matter," explains Peter Lodahl, Professor and head of the research group Quantum Photonics at the Niels Bohr Institute at the University of Copenhagen.
The researchers have developed a kind of single-photon cannon integrated on an optical chip. The optical chip consists of an extremely small photonic crystal that is 10 microns wide (1 micron is a thousandth of a millimeter) and 160 nanometers thick (1 nanometer is a thousandth of micron.) Embedded in the centre of the chip is a light source, a so-called quantum dot.
"What we then do is shine laser light on the quantum dot, where there are atoms with electrons in orbit around the nucleus. The laser light excites the electrons, which then jump from one orbit to another and thereby emit one photon at a time. Normally, light is scattered in all directions, but we have designed the photonic chip so that all of the photons are sent through only one channel," explains Søren Stobbe, Associate Professor of the Quantum Photonic research group at the Niels Bohr Institute.
Peter Lodahl and Søren Stobbe explain that it not only works, but also that it is extremely effective. "We can control the photons and send them in the direction we want with a 98.4 percent success rate. This is ultimate control over the interaction between matter and light and has amazing potential. Such a single-photon cannon has long been sought after in the research field and opens up fascinating new opportunities for fundamental experiments and new technologies," they explain.
The two researchers are in the process of patenting several parts of their work, with a specific goal of developing a prototype high-efficiency single-photon source, which could be used for encryption or for calculations of complex quantum mechanical problems and in general, is an essential building block for future quantum technologies. It is expected that the future's quantum technology will lead to new ways to code unbreakable information and to carry out complex parallel calculations.
For more information contact:
Peter Lodahl, Professor and head of the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen. Tel: +45 2056-5303, email@example.com
Søren Stobbe, Associate Professor in the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen. Tel: +45 6065-6769, firstname.lastname@example.org
Gertie Skaarup | Eurek Alert!
OU-led team discovers rare, newborn tri-star system using ALMA
27.10.2016 | University of Oklahoma
First results of NSTX-U research operations
26.10.2016 | DOE/Princeton Plasma Physics Laboratory
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Materials Sciences
27.10.2016 | Physics and Astronomy
27.10.2016 | Life Sciences