Physicists from Marburg and the US have succeeded in characterizing the quantum state of a system consisting of millions of particles by bringing experimental data and theoretical predictions into agreement.
The team of researchers headed by Professors Dr. Stephan Koch und Dr. Mackillo Kira from Philipps-Universität published their results in the renowned journal “Physical Review Letters”.
Modern semiconductor devices, chemical reactions and even biological behaviour are based on nanoscale processes with one nanometre being equal to one millionth of a millimetre. Processes on this scale operate according to the intricate principles of quantum mechanics which are in general highly complex and often unintuitive. In order to design and control such nanosystems, one has to understand the entire underlying quantum mechanic state.
“This objective is currently unreachable for any system larger than a few atoms or ions for the simple reason that the direct measurement of the quantum state would immediately exhaust all resources known to mankind concerning data acquisition, storing, and processing.” explained co-author Koch.
The scientists elegantly avoided this problem by optically exciting the electrons of thin semiconductor quantum wells. Instead of probing the quantum state directly, they carried out high precision measurements to detect subtle changes in the optical quantum-well absorption. Applying cutting-edge many-body theory, they performed rigorous comparisons of the experimental data and the theoretical predictions. „Our detailed comparison between quantitative experiment and theory showed that the absorption behaviour strongly depends on the many-body configuration.” remarked Kira. Thus, it was possible to identify the quantum states of the optically active electrons with a so far unprecedented accuracy.
“This result represents a first milestone towards the characterization of nanoscale processes in semiconductors,” commented Koch, and Kira added that one of the next steps would be to try to control the quantum state of large systems. This could potentially be performed in semiconductors by a detailed control of the quantum aspects of the optical excitation. This project will again be undertaken in cooperation with experimental physicists from the National Institute of Standards and Technology and the University of Colorado in den USA (JILA/NIST).
Original publication: R. P. Smith & al: „Extraction of Many-Body Configurations from Nonlinear Absorption in Semiconductor Quantum Wells”, Physical Review Letters 104 (2010), 247401, doi: 10.1103/PhysRevLett.104.247401Further Information:
Dr. Susanne Igler | idw
Graphene and quantum dots put in motion a CMOS-integrated camera that can see the invisible
30.05.2017 | ICFO-The Institute of Photonic Sciences
New Method of Characterizing Graphene
30.05.2017 | Universität Basel
Scientists have developed a new method of characterizing graphene’s properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials. Researchers from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics reported their findings in the journal Physical Review Applied.
Graphene consists of a single layer of carbon atoms. It is transparent, harder than diamond and stronger than steel, yet flexible, and a significantly better...
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
30.05.2017 | Life Sciences
30.05.2017 | Life Sciences
30.05.2017 | Physics and Astronomy