In cooperation with the Center for Nano-Optics of Georgia State University in Atlanta (USA), scientists of the Laboratory for Attosecond Physics of the Max Planck Institute of Quantum Optics and the Ludwig-Maximilians-Universität have made simulations of the processes that happen when a layer of carbon atoms is irradiated with strong laser light.
Electrons hit by strong laser pulses change their location on ultrashort timescales, i.e. within a couple of attoseconds (1 as = 10 to the minus 18 sec). In cooperation with the Center for Nano-Optics of Georgia State University in Atlanta (USA), scientists at the Laboratory for Attosecond Physics (LAP) of the Max Planck Institute of Quantum Optics (MPQ) and the Ludwig-Maximilians-Universität (LMU) have made simulations of processes that take place when electrons in a layer of carbon atoms interact with strong laser light.
The purpose of these simulations is to gain insight into light-matter-interactions in the microcosm. A better understanding of the underlying physical processes could lead to light-wave driven electronics that would operate at light frequencies, which is a hundred thousand times faster than state-of-the-art technologies. Graphene with its exceptional properties is considered to be very well suited as an example system for prototype experiments.
The closer we observe the motion of electrons, the better we understand their interaction with light. Many phenomena that arise in condensed matter due to strong-field light-matter interaction are not yet fully understood.
As the underlying processes occur within femto- or even attoseconds, it is difficult to access this intra-atomic cosmos: a femtosecond is a millionth of a billionth of a second; an attosecond is even a thousand times shorter. Experimental methods that shall cope with this challenge are at a development stage. However, it is possible to investigate these processes with the help of numerical simulations.
The team of scientists from LAP and Georgia State University has calculated what happens to electrons in graphene interacting with an intense laser pulse.
The laser field excites and displaces electrons, changing thus the charge density distribution. During this process, an extremely short electron pulse is scattered off the probe. The diffraction map of these matter waves reflects how the electron density distribution inside the graphene layer has been altered because of the laser pulse.
These simulations have revealed complex relations between the excitation of valence electrons by light and their subsequent ultrafast motion inside and between the carbon atoms in the graphene layer. Valence electrons are weakly bound and shared among neighbouring atoms. The scientists investigated their motion by identifying microscopic volumes that represent various chemical bonds and analysing the electric charge contained in these volumes.
During a laser pulse, there is a significant redistribution of the charge; at the same time, the displacement of the electrons caused by the electromagnetic field of the laser pulse is very small, less than a picometre (10 to the minus 12 m). In addition to that, the calculations showed that the light-induced electric current has an inhomogeneous microscopic distribution, flowing along the chemical bonds between the carbon atoms.
These simulations should assist new ultrafast electron diffraction measurements. “We will possibly detect new phenomena, and perhaps observe deviations from our predictions”, project leader Vladislav Yakovlev points out. “But we are pretty sure that quite some fundamental physics is waiting to be observed in challenging but feasible atomic-scale measurements.” [Thorsten Naeser/Olivia Meyer-Streng]
Vladislav S. Yakovlev, Mark I. Stockman, Ferenc Krausz & Peter Baum
Atomic-scale diffractive imaging of sub-cycle electron dynamics in condensed matter
Scientific Reports, 28. September 2015, doi: 10.1038/srep14581
Dr. Peter Baum
Max Planck Institute of Quantum Optics
Am Coulombwall 1, 85748 Garching
Phone: +49 (0)89 / 289 - 14102
Dr. Vladislav Yakovlev
Center for Nano-Optics
Georgia State University
Atlanta, GA 30303, USA
Prof. Dr. Ferenc Krausz
Chair of Experimental Physics,
Laboratory for Attosecond Physics
Director at Max Planck Institute of Quantum Optics, Garching, Germany
Phone: +49 (0)89 32 905 - 600
Telefax: +49 (0)89 32 905 - 649
Dr. Olivia Meyer-Streng
Press & Public Relations
Max Planck Institute of Quantum Optics, Garching, Germany
Phone: +49 (0)89 32 905 -213
Dr. Olivia Meyer-Streng | Max-Planck-Institut für Quantenoptik
First results of NSTX-U research operations
26.10.2016 | DOE/Princeton Plasma Physics Laboratory
Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
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...
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...
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...
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...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Life Sciences
27.10.2016 | Life Sciences
27.10.2016 | Power and Electrical Engineering