Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Quantum-Memory Imprint discovered in Light Emission


Physicists at Marburg University assign unexpected experimental results to a quantum memory.

Prior to this work, ideal light sources (such as perfect lasers) were thought to emit as much light as excited in them via pumping.

Semiconductor quantum-dot microring laser emits light whose emission intensity exhibits oscillations due to quantum memory between excitation and light Emission. Pressestelle der Philipps-Universität Marburg/Fachgebiet Theoretische Halbleiterphysik

Physicists from Marburg, Dortmund, St. Petersburg, and Notre Dame, USA, investigated optically pumped quantum-dot lasers and demonstrated that the pumping induces a quantum memory between the pump excitation and the light emission. Beating expectations, this quantum-memory was shown to induce intensity oscillations on top of the expected linear output.

Even more striking, these oscillations could be either suppressed or significantly enhanced via the quantum fluctuations of the pump laser. This breakthrough will be published in the coming issue of the journal Physical Review Letters on 15.08.2014.

The theoretical research team led by Professors Mackillo Kira and Stephan W. Koch from the Philipps-Universität Marburg analyzed the unusual experimental results obtained by the team led by Prof. Manfred Bayer. The experimentalists used laser light to excite quantum dots inside a microcavity and carefully recorded the subsequent light emission.

The first author of this publication, M.Sc. Christian Berger, explains “The input pump laser excites the quantum dot to a higher energy level; afterwards, the excitation returns to the ground state by emitting light, defining the output”.

Surprisingly, the authors found that the output intensity does not scale linearly with the input intensity as expected earlier. Instead, the output power was oscillating around its expected value. They could even show that the oscillations can be completely controlled by the quantum-optical fluctuations of the optical pump, which highlights the significance of this extraordinary discovery.

Mackillo Kira elaborates, “We were thrilled after we verified the quantum-optical control of these oscillations which is a genuine property of our quantum-optical spectroscopy concept”. Manfred Bayer continues, “Based on these findings, we could unambiguously identify the observed oscillations as a genuine quantum-memory effect”. Stephan W. Koch explains the origin of the quantum memory, “The light emission remembers the earlier excitation process via quantum memory – this effect is intimately connected with entanglement, which is one of the manifestations of the fundamental quantum weirdness”.

This work is connected with the ongoing effort to convert quantum-world phenomena to tangible applications. The existence of quantum-memory effects and their quantum-optical control may hold the key to developing lasers whose quantum-optical aspects become completely user defined. Such laser sources would be extremely useful in quantum-information science and in quantum spectroscopy which aims to control quantum processes of complex systems via the quantum aspects of light.

Professors Mackillo Kira and Stephan W. Koch teach semiconductor quantum optics and theoretical semiconductor physics at the Philipps-Universität Marburg. In February, they identified a new quasiparticle, the dropleton, with the help of quantum-optical spectroscopy.

Publication: Christian Berger & al.: Quantum-Memory Effects in the Emission of Quantum-Dot Microcavities, Physical Review Letters 2014.

Further information:
German version of this press release:

Professor Dr. Mackillo Kira
Field: Theoretical Semiconductor Physics
Phone: 06421 2824222

Weitere Informationen:

Dr. Susanne Langer | idw - Informationsdienst Wissenschaft

Further reports about: Emission fluctuations lasers oscillations pump semiconductor spectroscopy

More articles from Physics and Astronomy:

nachricht Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters

nachricht Light-driven atomic rotations excite magnetic waves
24.10.2016 | Max-Planck-Institut für Struktur und Dynamik der Materie

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: Light-driven atomic rotations excite magnetic waves

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...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

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...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

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...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

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...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Enormous dome in central Andes driven by huge magma body beneath it

25.10.2016 | Earth Sciences

First time-lapse footage of cell activity during limb regeneration

25.10.2016 | Life Sciences

Deep down fracking wells, microbial communities thrive

25.10.2016 | Earth Sciences

More VideoLinks >>>