Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A cavity leads to a strong interaction between light and matter

22.10.2019

Researchers have succeeded in creating an efficient quantum-mechanical light-matter interface using a microscopic cavity. Within this cavity, a single photon is emitted and absorbed up to 10 times by an artificial atom. This opens up new prospects for quantum technology, report physicists at the University of Basel and Ruhr-University Bochum in the journal Nature.

Quantum physics describes photons as light particles. Achieving an interaction between a single photon and a single atom is a huge challenge due to the tiny size of the atom. However, sending the photon past the atom several times by means of mirrors significantly increases the probability of an interaction.


A microscopic cavity of two highly reflective mirrors is used to allow an enclosed artificial atom (known as a quantum dot) to interact with a single photon.

University of Basel, Department of Physics

In order to generate photons, the researchers use artificial atoms, known as quantum dots. These semiconductor structures consist of an accumulation of tens of thousands of atoms, but behave much like a single atom: when they are optically excited, their energy state changes and they emit a photon.

“However, they have the technological advantage that they can be embedded in a semiconductor chip,” says Dr. Daniel Najer, who conducted the experiment at the Department of Physics at the University of Basel.

System of quantum dot and microcavity

Normally, these light particles fly off in all directions like a light bulb. For their experiment, however, the researchers positioned the quantum dot in a cavity with reflective walls. The curved mirrors reflect the emitted photon back and forth up to 10,000 times, causing an interaction between light and matter.

Measurements show that a single photon is emitted and absorbed up to 10 times by the quantum dot. At the quantum level, the photon is transformed into a higher energy state of the artificial atom, at which point a new photon is created. And this happens very quickly, which is very desirable in terms of quantum technological applications: one cycle lasts just 200 picoseconds.

The conversion of an energy quantum from a quantum dot to a photon and back again is theoretically well supported, but “nobody has ever observed these oscillations so clearly before,” says Professor Richard J. Warburton from the Department of Physics at the University of Basel.

Serial interaction of light and matter

The successful experiment is particularly significant because there are no direct photon-photon interactions in nature. However, a controlled interaction is required for use in quantum information processing.

By transforming light into matter according to the laws of quantum physics, an interaction between individual photons becomes indirectly possible – namely, via the detour of an entanglement between a photon and a single electron spin trapped in the quantum dot. If several such photons are involved, quantum gates can be created through entangled photons. This is a vital step in the generation of photonic qubits, which can store information by means of the quantum state of light particles and transmit them over long distances.

International collaboration

The experiment takes place in the optical frequency range and places high technical demands on the size of the cavity, which must be adapted to the wavelength, and the reflectivity of the mirrors, so that the photon remains in the cavity for as long as possible.

The semiconductor quantum dots and one mirror of the cavity were made by the team headed by Professor Andreas D. Wieck and Dr. Arne Ludwig at Ruhr-University Bochum; the other mirror was made at the Université de Lyon. Theoretical support was provided by the quantum optics theory group led by Professor Nicolas Sangouard at the University of Basel.

Financial resources for the Basel researchers came from NCCR QSIT, the Swiss National Science Foundation and Horizon 2020.

Wissenschaftliche Ansprechpartner:

Prof. Dr. Richard J. Warburton, University of Basel, Department of Physics, tel. +41 61 207 35 60, email: richard.warburton@unibas.ch

Originalpublikation:

Daniel Najer, Immo Söllner, Pavel Sekatski, Vincent Dolique, Matthias C. Löbl, Daniel Riedel, Rüdiger Schott, Sebastian Starosielec, Sascha R. Valentin, Andreas D. Wieck, Nicolas Sangouard, Arne Ludwig & Richard J. Warburton
A gated quantum dot strongly coupled to an optical microcavity
Nature (2019), doi: 10.1038/s41586-019-1709-y
https://www.nature.com/articles/s41586-019-1709-y

Reto Caluori | Universität Basel
Further information:
http://www.unibas.ch

More articles from Physics and Astronomy:

nachricht TU Graz researchers develop new 3D printing for the direct production of nanostructures
13.11.2019 | Technische Universität Graz

nachricht A new approach to the hunt for dark matter
13.11.2019 | Johannes Gutenberg-Universität Mainz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New Pitt research finds carbon nanotubes show a love/hate relationship with water

Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.

New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...

Im Focus: Magnets for the second dimension

If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.

Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...

Im Focus: A new quantum data classification protocol brings us nearer to a future 'quantum internet'

The algorithm represents a first step in the automated learning of quantum information networks

Quantum-based communication and computation technologies promise unprecedented applications, such as unconditionally secure communications, ultra-precise...

Im Focus: Distorted Atoms

In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.

An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort...

Im Focus: A Memory Effect at Single-Atom Level

An international research group has observed new quantum properties on an artificial giant atom and has now published its results in the high-ranking journal Nature Physics. The quantum system under investigation apparently has a memory - a new finding that could be used to build a quantum computer.

The research group, consisting of German, Swedish and Indian scientists, has investigated an artificial quantum system and found new properties.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

Smart lasers open up new applications and are the “tool of choice” in digitalization

30.10.2019 | Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

 
Latest News

Magnetic tuning at the nanoscale

13.11.2019 | Physics and Astronomy

At future Mars landing spot, scientists spy mineral that could preserve signs of past life

13.11.2019 | Physics and Astronomy

Necessity is the mother of invention: Fraunhofer WKI tests utilization of low-value hardwood for wood fiberboard

13.11.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>