Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum-Memory Imprint discovered in Light Emission

12.08.2014

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: http://www.uni-marburg.de/aktuelles/news/2014c/quantengedaechtnis

Contact:
Professor Dr. Mackillo Kira
Field: Theoretical Semiconductor Physics
Phone: 06421 2824222
E-Mail: mackillo.kira@physik.uni-marburg.de

Weitere Informationen:

http://www.uni-marburg.de/fb13/research/theoretical-semiconductor-physics/index_...

Dr. Susanne Langer | idw - Informationsdienst Wissenschaft

Further reports about: Emission fluctuations lasers oscillations pump semiconductor spectroscopy

More articles from Physics and Astronomy:

nachricht Introducing the disposable laser
04.05.2016 | American Institute of Physics

nachricht New fabrication and thermo-optical tuning of whispering gallery microlasers
04.05.2016 | Okinawa Institute of Science and Technology (OIST) Graduate University

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: Nuclear Pores Captured on Film

Using an ultra fast-scanning atomic force microscope, a team of researchers from the University of Basel has filmed “living” nuclear pore complexes at work for the first time. Nuclear pores are molecular machines that control the traffic entering or exiting the cell nucleus. In their article published in Nature Nanotechnology, the researchers explain how the passage of unwanted molecules is prevented by rapidly moving molecular “tentacles” inside the pore.

Using high-speed AFM, Roderick Lim, Argovia Professor at the Biozentrum and the Swiss Nanoscience Institute of the University of Basel, has not only directly...

Im Focus: 2+1 is Not Always 3 - In the microworld unity is not always strength

If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”

In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

New fabrication and thermo-optical tuning of whispering gallery microlasers

04.05.2016 | Physics and Astronomy

Introducing the disposable laser

04.05.2016 | Physics and Astronomy

A new vortex identification method for 3-D complex flow

04.05.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>