Researchers of the Center for Integrated Quantum Science and Technology IQST at the 5th Institute of Physics at the University of Stuttgart (Head: Prof. Tilman Pfau) have developed a novel, promising variant of a light source for the smallest possible energy packages - a so-called single-photon source. Their work has been published in the latest issue of the journal Science.*
A photon is the smallest conceivable amount of light. Classical light sources such as light bulbs or the sun emit many photons simultaneously, in random order. A single photon source on the other hand, emits only a single photon in a controlled way.
Such light sources have been known for about 20 years, but the various approaches (e.g. quantum dots or nitrogen defect centers in diamonds) are hot topics in research worldwide. The special feature of this new light source is that it can be operated without expensive cooling methods that need liquid gases or lasers.
The secret lies in the glass cell
The Stuttgart-based single-photon source works with atomic gases at room temperature for the first time. The secret lies in a credit card-sized glass cell filled with a vapor of rubidium atoms. The quantum character of the generated light is based on strong interactions between the individual atoms in the vapor cell. In order for the atoms to interact strongly, they are brought into highly excited Rydberg states by laser light.
These are states in which the outermost electron of each atom is particularly far away from the rest of the atom. Due to their enormous size, the interaction between two Rydberg atoms is very strong. A single Rydberg excitation does not allow another Rydberg atom in its vicinity and thus blocks the entire atomic cloud.
"Since the atoms are trapped in a microscopically small glass cell, only one Rydberg excitation can ever occur in this cell - no matter how many atoms are trapped in the cell," explains Fabian Ripka, a PhD student at the 5th Institute of Physics at the University of Stuttgart. When this single excitation subsides again, a single quantum of light - a photon - is emitted. The Stuttgart researchers can specifically control the Rydberg excitation and the emission of the photon.
Individual photons already play an important role in quantum technology applications. Since they cannot be copied unnoticed, they are suitable, for example, for tap-proof quantum communication and are used in quantum cryptography. Prof. Tilman Pfau also sees great potential for single photons in so-called quantum computers. "In photonic networks, single-photon sources will be an essential component for performing quantum algorithms," says the quantum physicist.
The Center for Integrated Quantum Science and Technology IQST, a center for quantum sciences funded by the state of Baden-Württemberg, is a consortium of the Universities of Stuttgart and Ulm and the Max Planck Institute for Solid State Research in Stuttgart. The aim of the center is to promote synergies between physics and related natural and engineering sciences and to represent quantum science from the basics to technological applications.
Researchers at the 5th Physics Institute led by Prof. Tilman Pfau are investigating the quantum properties of atoms in the IQST and are trying to control them in a targeted way in their search for new states of matter or possible applications for quantum information technology and quantum optics.
Prof. Dr. Tilman Pfau, Universität Stuttgart, Tel.: +49 (0)711/685 64820, Mail: email@example.com
Fabian Ripka, Harald Kübler, Robert Löw, Tilman Pfau: A room-temperature single-photon source based on strongly interacting Rydberg atoms, Science from 26.10.2018, Vol. 362, Issue 6413, pp. 446-449, DOI: 10.1126/science.aau1949
Andrea Mayer-Grenu | idw - Informationsdienst Wissenschaft
Levitating objects with light
19.03.2019 | California Institute of Technology
19.03.2019 | Leibniz-Institut für Astrophysik Potsdam
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum
For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...
Physicists in the EPic Lab at University of Sussex make crucial development in global race to develop a portable atomic clock
Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock - devices...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
20.03.2019 | Life Sciences
20.03.2019 | Life Sciences
20.03.2019 | Trade Fair News