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Life on Earth is based on a natural symbiosis of electrons and light: the motion of electrons creates light that supplies life-giving energy for our globe and transforms light into biological energy and signals, which in turn allow plants to grow and animals and humans to see. Beyond being vital for life, these motions can also be fatal, upon modifying molecular structures and hence affecting biological function. At the most fundamental level, electrons maintain and end life in biological systems, and serve and save lives in technical devices.

The force fields of laser light, if precisely controlled, permit steering and observing electronic motions and vice versa, controlled electronic motions enable the generation and probing of such fields, extending the symbiosis of light and electrons from nature to technology. These control capabilities open novel routes to extending the repertoire with which physics is able to advance technology and assist medicine.

With controlled forces of light – from terahertz (infrared) to petahertz (ultraviolet) frequencies – we induce, control and probe electric current at atomic scales in space and time with the aim to explore the ultimate frontiers of electron-based signal processing and identify viable routes towards those frontiers.

In a similar way, we induce, control and probe structural and electronic dynamics of molecules of living systems with the aim to acquire and identify fingerprints of their abnormal physiologies. We focus on evaluating the ability of field-resolved-spectroscopic fingerprinting to detect and classify cancer at the earliest stages of its development and monitor its response to therapy.

We feel obliged to disseminate the knowledge and expertise we acquire and are glad to share our findings and provide advice and technical assistance to researchers of any public institution of the world committed to serving mankind by advancing science, technology or medicine. Do get in touch if you are interested!

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This attosecond-resolution photograph taken in 2004 has been chosen to represent the joint Ludwig Maximilians University (LMU)-Max Planck Institute of Quantum Optics (MPQ) Laboratory for Attosecond Physics (LAP), established in the same year. It reveals a snapshot of a wave of red laser light, recorded with attosecond flashes of light, establishing attosecond metrology.

Milestones

  • 2000: Atomic motions deciphered

    2000: Atomic motions deciphered

    Femtochemistry comes of age.1 Molecular dynamics is routinely captured via femtosecond light pulses.

    When scientists started to „take pictures“ of the movements of atoms in molecules during chemical reactions at the end of the 1980s, this had little to do with conventional photography. The basic principle, however, remained the same: A short exposure time was needed to »freeze« the dynamics under scrutiny and display changes of the microscopic states of matter in a series of snapshots taken at different instant during the evolution of the system. The atomic composition and/or structure of molecules can change within femtoseconds, i.e. within millionths of a billionth of a second. The required ultrashort exposure time was provided by femtosecond laser pulses.

    The 1999 Nobel Prize in Chemistry honoured the pioneering contributions of Prof. Ahmed Zewail from CALTECH to establishing femtochemistry, permitting the observation of changes in the atomic structure and/or composition of molecules in real time. In spite of these breathtaking advances, several mysteries remained unresolved.

    How do the electrons move prior to changes in atomic structure and how does initial electron dynamics influence the fate of the molecule? How does electron-nuclear coupling affect reaction pathways? Answers to them called for even faster techniques, reaching out into the attosecond domain, the characteristic time scale of electronic motions at the atomic scale.

  • 2001: A new dimension of time

    2001: A new dimension of time

    Scientists – for the first time – succeed in producing and measuring light flashes which last less than one femtosecond in an experiment1 what, according to Yaron Silberberg (Weizmann Institute), »might be the dawn of attophysics — the study of dynamics on timescales fast enough to follow electronic motion within atoms.«2 Independently, researchers in Paris demonstrated trains of such pulses, following upon each other every half cycle of the laser field used for their generation and measurement.3 In both cases, the electric field of near-infrared (NIR) laser pulses were used for both the generation and measurement of XUV light varying on an attosecond scale. In the generation process, the NIR field tunnel ionized atoms on its wave crests and the detached electron returning to the vicinity of its parent ion emitted a burst of extreme ultraviolet (XUV) light. The process was repeated each half cycle of the driving laser light, resulting in a train of sub-femtosecond bursts in the experiment of Paul et al. using multi-cycle driving fields.4 By contrast, in the Vienna experiment5 confining the ionization largely to the central field cycle along with careful high-pass filtering of the emitted XUV light isolated a single burst from the train emitted in the experiment of Paul et al. This lead to the production of a single sub-femtosecond pulse by each near-infrared laser pulse. These tools opened the door towards the first attosecond real-time observation of electron dynamics.

  • 2002: Diving deep into the atom

    2002: Diving deep into the atom

    For the first time, real-time access to electron processes deep inside the atom is obtained in a study1 that, according to Louis DiMauro (Brookhaven National Laboratory), »…announce the beginning of a new era…. We are entering a new realm of hyperfast measurements; the age of attophysics has begun.«2

    For more than a decade it has already been possible to explore the movements of atoms and molecules during chemical reactions by means of femtosecond laser pulses. However, the considerably lighter electrons are much quicker: Deep inside atoms, a vacant quantum state, i.e. a »hole«, may be filled by an electron at the »margin« of an atom within a few hundred to several thousand attoseconds. With the help of 650-attosecond extreme ultraviolet flashes X-ray flashes it is now possible to observe such a transition between two quantum states nearby the atomic nucleus directly. As the graphical artist of the New York Times visualized, the attosecond flash knocks out an electron from an inner shell of an atom (in this case: krypton atom). Electrons at the »margin« of the atom try to fill up the «hole« as quickly as possible. During that process, energy is released through the emission of a second electron, an Auger electron, as it is called. The emission time of the Auger electron is captured by the field of the infrared laser pulse previously used for the generation of the attosecond burst and hence being perfectly synchronized to it. These tools have opened the door for gaining direct, time-resolved insight into the way electrons move in an excited atom.

  • 2003: Control of light waves

    2003: Control of light waves

    Laser pulses with a reproducible waveform and hence perfectly controlled temporal evolution of their electric field on an attosecond scale are generated, a feat which, according to Philip H. Bucksbaum (University of Michigan, Ann Arbor), »…marks the beginning of the era of ‘attophysics’ — the study of physical processes on the attosecond timescale.«1 They contain only a few wave oscillations.

    Capitalizing on the frequency-comb technique invented by Prof. Theodor Hänsch (Max Planck Institute of Quantum Optics), which allowes precise control of the frequencies of the phase-locked modes of a femtosecond laser oscillator, researchers at the Vienna University of Technology, in collaboration with the group of Prof. Hänsch, produced a train of intense few-cycle laser pulses with precisely-controlled oscillations of their electric and magnetic fields.

    These controlled fields imply controlled forces acting upon electrons, allowing, for the first time the control of electronic motions in atomic systems on an attosecond time scale. The first spectacular consequences of this newly-emerged capability are the generation of isolated attosecond pulses with precisely controlled characteristics and the measurement of the electric field of light, briefly: precision attosecond metrology.

  • 2004: Precision attosecond metrology

    2004: Precision attosecond metrology

    The controlled electric force field of waveform-controlled light generates reproducible attosecond pulses and a streak »camera« operated with these controlled fields accurately characterizes these flashes1 and uses them for measuring oscillating light fields.2 The use of attosecond flashes and controlled few-cycle laser fields for capturing hyperfast electronic motions requires their accurate characterization. To this end, the flashes knock out electrons from atoms, which – depending on their moment of release – are accelerated or decelerated by the controlled electric field of the few-cycle pulse that previously generated the attosecond pulse and is beamed in simultaneously. As a result, the temporal profile of the attosecond photoemission is mapped to a final momentum distribution recorded in the light-field-driven streak camera. Recording these »streak images« as a function of delay between the attosecond pulse and the streaking laser field yields what has been referred to as the attosecond streaking spectrogram. This allows retrieval of both the electric field waveform of the laser pulse and the intensity envelope and frequency sweep of the attosecond pulse inducing the photoemission, which, meanwhile, is routinely produced with sub-100-as duration.3 Ever since their first demonstration, controlled few-cycle laser fields and reproducible isolated attosecond pulses constitute the main tools for attosecond measurements with light-field-driven streaking serving as a gold standard for precision attosecond metrology.

  • 2007: On the scent of electrons

    2007: On the scent of electrons

    Electron tunnelling in atoms1 and Angstrom-scale electric charge transport in solids2 can now be scrutinized directly in the time domain.

    With techniques for the reproducible generation and reliable measurement of attosecond pulses and controlled near-single-cycle laser fields in place, widespread applications to real-time observation and control of electronic processes in atomic, molecular and solid-state systems could begin. The temporal dynamics of fundamental processes such as electron tunnelling during strong-laser-field-induced ionization of atoms and Angstrom-scale electric charge transport through atomic layers of solids can now be tracked directly in the time domain.

  • 2010: Real time access to electron motion

    2010: Real time access to electron motion

    Attosecond-tools provide realtime access to electron motion.

    Whereas the former study provides fundamental insight into strong-field-atom interactions, the latter capability will be beneficial to advancing electronics towards its ultimate speed limits, to light-wave frequencies. Meanwhile, these tools also provide real-time access to valence electron motion inside atoms1 as well as molecules.

    Moreover, precision measurement of the timing of photoemission with a precision of less than 10 attoseconds now reveals the role of electron correlations in this fundamental process.2

  • 2011: Tailor-made light waves

    2011: Tailor-made light waves

    Synthesized waveforms of light-pulses consist of less than a full oscilation.

    In order to control electrons, the waveform of light must be tailored within one oscillation period. That requires »ultra white« laser light, which involves not only all colours of the visible spectrum, but also infrared and ultraviolet waves, as well as a tool which combines these waves oscillating at different speeds. In 2011, LAP researchers developed a »light wave synthesizer«, as it is called, which allows the control of the oscillation of light with state-of-the-art precision. Using this technology, the scientists succeeded in creating completely new waveforms in the pulses. They may now consist of less than a full oscillation and hence last only around two femtoseconds. With that the physicists generated the shortest flashes of visible light observed to this day. It is now possible to control the temporal evolution of the force exerted by light on the attosecond scale. Thus, the technology promises, for the first time, the precise control of electron movements. Since all the energy of the electromagnetic field clusters in a tiny time window, the new tool allows for a stimulation of processes within one femtosecond and opens the door to the attosecond pump-probe experiments.1

Cover stories

  • Infrared Lasers

    Infrared Lasers

    In article number 1700273, Jinwei Zhang and co‐workers investigate two different gain materials, Tm:YAG and Ho:YAG, in thin‐disk configuration. Using a 72‐pass pump cavity, thin‐disk lasers with high powers and optical‐to‐optical efficiencies at 2 µm are realized, paving the way for further scaling of power towards kW‐level based on thin‐disk technology. The image was made and processed by Thorsten Naeser, Dennis Luck, and Kilian Fritsch together with the authors of this manuscript.

  • Prominently placed

    Prominently placed

    A paper written by Drs. Yuya Morimoto and Peter Baum of the Laboratory for Attosecond Physics, which is jointly run by LMU Munich and the Max Planck Institute for Quantum Optics, is featured on the cover of the March 2018 issue of Nature Physics. Its authors have developed a novel form of electron microscopy, which allows light-matter interactions to be observed in real time at atomic resolution. The new method thus makes it possible to visualize atomic processes as they unfold in space and time. In the experiments described in the report, the Munich researchers make use of the oscillating electric field of laser light to ‘chop’ an electron beam into a sequence of attosecond pulses. By focusing the pulse trains on a silicon crystal, they were able to observe, in real time, how the electromagnetic waveform propagates within the crystal, as well as the relationship between the diffraction of the electrons by atoms in the crystal and the phase of the optical field. The cover picture shows a superimposition of data obtained from a set of time-delayed measurements, and reveals how the Bragg-reflections that make up the diffraction pattern change when varying the delay of the light-cycle excitation.

  • Signal control with light frequencies

    Signal control with light frequencies

    Light waves have the potential to boost the efficiency of conventional electronics by a factor of 100,000. In a review article that appears in »Nature Photonics« on March 14th, Prof. Ferenc Krausz of the Laboratory for Attosecond Physics (LAP) at the Max-Planck-Institut für Quantenoptik and the Ludwig-Maximilians-Universität München and his co-author Prof. Mark Stockman of Georgia State University (GSU) in Atlanta describe how this vision may one day come true. In their scenario, one would exploit the electric field of laser light to control the flow of electrons in dielectric materials, which, in turn, may modulate transmitted light and switch current in electronic circuits at light frequencies. Visible light oscillates at frequencies of about 1015 cycles per second, opening the possibility of switching light or electric current at rates in this range. And since both signals can also carry information, innovative optoelectronic technologies would enable a corresponding increase in the speed of data processing, opening a new era in information technology. The authors review the novel tools and techniques of attosecond technology, which may play a crucial role in making the above advances actually happen.

  • Ultraschneller Tauchgang in die Atome

    Ultraschneller Tauchgang in die Atome

    In 2001, when scientists around Prof. Ferenc Krausz for the first time succeeded to produce light flashes which only lasted attoseconds, a new era was ushered in natural sciences. Attosecond physics was born. Now, it should be possible to observe electrons and hence wrench the microcosm one of its most closely guarded secrets. In his book Ultraschneller Tauchgang in die Atome, Thorsten Naeser, head of press and public relations within the cluster of excellence Munich-Centre for Advanced Photonics (MAP), talks about the development of attosecond physics. Building upon the basics of quantum mechanics, laser physics and chronophotography, Thorsten Naeser describes how electrons can be captured in images today: with light flashes which last only a few billionth of a billionth second. Thorsten Naeser also picturesquely describes numerous results attosecond physics has brought to this day and where the road of exploring quantum particles may lead. The book is written in German.

  • Ultrafast phenomena on the nanoscale

    Ultrafast phenomena on the nanoscale

    The fast paced field of ultrafast nanoscience exploits both ultrafast optics and nanostructuring techniques to explore new phenomena, ranging from plasmonic coupling of light and matter to attosecond physics. The special issue edited by Peter Hommelhoff, Matthias Kling and Mark Stockman, highlights the recent rapid progress in the field. Ultrafast phenomena described in the contributed articles include linear and non-linear effects over a wide range of applications including one- and multidimensional (spatially resolved) spectroscopies, time-resolved measurements of localized and propagating surface plasmons, the dynamics of nanostructures in ultrashort and ultrastrong fields, the ultrafast emission of electrons, the coherent generation of light including high-harmonic generation, and nanoscale devices, which contribute to the development of ultrafast nanoscale electronics.

  • A laser-driven nanosecond proton source for radiobiological studies

    A laser-driven nanosecond proton source for radiobiological studies

    Ion beams are relevant for radiobiological studies and for tumor therapy. In contrast to conventional accelerators, laser-driven ion acceleration offers a potentially more compact and cost-effective means of delivering ions for radiotherapy. Here, Jianhui Bin and co-workers show that by combining advanced acceleration using nanometer thin targets and beam transport, truly nanosecond quasi-monoenergetic proton bunches can be generated with a table-top laser system, delivering single shot doses up to 7Gy to living cells. Although in their infancy, laser-ion accelerators allow studying fast radiobiological processes as demonstrated here by measurements of the relative biological effectiveness of nanosecond proton bunches in human tumor cells.

  • Invited Article: Attosecond photonics: Synthesis and control of light transients

    Invited Article: Attosecond photonics: Synthesis and control of light transients

    Ultimate control over light entails the capability of crafting its field waveform. Here, Mohammed Th. Hassan and co-workers describe in an invited article the technological advances that have recently permitted the synthesis of light transients confinable to less than a single oscillation of its carrier wave and the precise attosecond tailoring of their fields. The work opens the door to light field based control of electrons on the atomic, molecular, and mesoscopic scales. The team presents the technology of what is believed to be a new realm in light control: the synthesis of subcycle transients of the electromagnetic field and the attosecond tailoring of its waveform. Whereas subcycle field synthesis requires the manipulation of coherent, superoctave light sources, its successful implementation is compatible with the subdivision of this bandwidth into a limited number of constituent spectral channels as long as dispersion affective of the pulses in each of these channels is possible. The light fieldsynthesis concepts detailed in this work also affords scalability over several more optical octaves by the introduction of additional spectral channels in the deep and vacuum ultraviolet, as well as in the infrared region of the spectrum.

  • Elektronen unter Kontrolle

    Elektronen unter Kontrolle

    With the help of ultrashort light pulses, electrons in molecules and nanostructures can be controlled and observed on attosecond time scales. While the atomic nuclei in molecules and nanostructures typically move on a femtosecond time scale, the dynamics of the much lighter electrons run around a thousand times faster on an attosecond time scale, i.e. 0,000,000,000,000,000,001 seconds! Nevertheless, new techniques make it possible to control these movements and to film them. This promises the targeted control of chemical reactions or purely optical circuits. Matthias Kling and Marc J.J. Vrakking explain the latest developments in attosecond physics. (Article in German)

  • Attosecond Physics – the first decade. On the route to tiny time scales

    Attosecond Physics – the first decade. On the route to tiny time scales

    Deep inside matter, our ideas of time lose their validity. Light flashes which last only a few millionths to billionths of a billionth second snatch from the microcosm its closely guarded secrets: Electron movements become visible. Quantum phenomena can be examined in real time. The control of elementary particles comes within reach. Responsible for all that is the young science of attosecond physics, "born" in 2001, when Prof. Ferenc Krausz succeeded in producing and measuring light flashes which last less than one femtosecond. Krausz founded the Laboratory for Attosecond Physics (LAP) which is located at the Max Planck Institute for Quantum Optics in Garching, Germany. Here is the history of how Attosecond Physics has been developed in LAP over the last ten years.

  • Sub-femtosecond sculpted light transients probe the atom

    Sub-femtosecond sculpted light transients probe the atom

    Attosecond (as) photonics is a rapidly developing tool to help scientists study the behavior of matter and energy at this extraordinarily short time scale. Now, the research group around Dr. Eleftherios Goulielmakis, lead researcher with the Max Planck Institute for Quantum Optics has reached a new milestone: the shaping and attosecond sampling of »light transients« within a 2.4 fs time span over a 0.3–0.9 PHz frequency range. Light transients are nonrepeating sculpted waveforms that are completely confined to a single cycle, or at most a few cycles. On-demand waveforms with customized field evolution and sub-femtosecond rise times and confinements are now possible with petahertz-scale field synthesis. These shaped transients allow physicists to probe the properties of electron behavior within atoms with great detail.

  • A Decade in Attosecond Science

    A Decade in Attosecond Science

    The year 2011 marks the 10th anniversary of an important advance in ultrafast laser pulses: For the first time, laser physicists were able to break the femtosecond barrier to create attosecond pulses – the shortest light pulses ever generated in the laboratory. The first single isolated pulses lasting for less than 1 fs (measured at 650 as) were produced in 2001 by Dr. Reinhard Kienberger and professor Ferenc Krausz and his group at the Vienna University of Technology in Austria. Today, Krausz is director of the Max Planck Institute of Quantum Optics and professor at Ludwig Maximilian University, both in Munich, Germany. 

  • Real-time observation of valence electron motion

    Real-time observation of valence electron motion

    An international team from the Laboratory for Attosecond Physics (attoworld.de), led by Prof. Ferenc Krausz at the Max Planck Institute of Quantum Optics and the Ludwig- Maximilians-Universität in Munich, in collaborations with researchers from the United States and Saudi Arabia, have observed, for the first time, the quantum-mechanical behaviour occurring at the location in a noble gas atom where, shortly before, an electron had been ejected from its orbit. The researchers achieved this result using light pulses which last only slightly longer than 100 attoseconds.

  • Tripling in neon produces 2.8 fs deep-UV pulses

    Tripling in neon produces 2.8 fs deep-UV pulses

    Femtosecond and attosecond light pulses are now allowing scientists to deeply explore the workings of atoms, molecules and nanoparticles, writes John Wallace in his article. For example few-cycle deep ultraviolet pulses fired at molecules can manipulate valence-shell electrons, preparing the molecules for high-resolution study via attosecond spectroscopy. Up to now, the shortest pulses created in the deep-UV range have been about 3.7 fs in duration (attosecond pulses consist of light at shorter extreme-UV wavelengths). But a direct-frequency-conversion approach developed by researchers at Max-Planck-Institut für Quantenoptik, Technische Universität München, and Ludwig-Maximilians-Universität (all of Garching, Germany) and King Saud University (Riyadh, Saudi Arabia) produces deep-UV pulses only 2.8 fs long, with pulses less than 1 fs a possibility.

  • Delay in photoemission

    Delay in photoemission

    When light is absorbed by atoms, the electrons become excited. If the light particles, so-called photons, carry sufficient energy, the electrons can be ejected from the atom. This effect is known as photoemission and was explained by Einstein more than hundred years ago. Until now, it has been assumed that immediately after the impact of the photons the electrons start moving out of the atom. This point in time can be detected and has so far been considered as coincident with the arrival time of the light pulse, i.e. with "time zero" in the interaction of light with matter. Using their ultra-short time measurement technology, physicists from the Laboratory for Attosecond Physics at the Max Planck Institute of Quantum Optics (MPQ), the Ludwig-Maximilians-Universität in Munich (LMU) and the Technische Universität München (TUM), along with their collaborators from Austria, Greece, and Saudi Arabia, have now tested this assumption. Their measurements revealed that electrons excited simultaneously by a light pulse from different atomic orbitals leave the atom with a small but measurable time delay of about twenty attoseconds. One attosecond is one billionth of one billionth of a second. These new findings contradict the earlier assumption that the electrons leave the atom immediately after the light pulse has hit. The June 25th issue of Science magazine features these spectacular scientific insights on its cover.

  • In Pursuit of the Briefest Beat

    In Pursuit of the Briefest Beat

    Attosecond pulses of light could open electrons’ fast-paced world. Science writer Charles Petit tells the story of attosecond physics beginning with Paul Corkum. Corkum is a laser and plasma physicist with Canada’s National Research Council and the University of Ottawa. His vision, in 1993, led him to become a pioneer in a field of attosecond science. Charles Petitis telling a dramatic thriller around Corkum. The actors were the pulsating electric fields of ordinary infrared laser beams and the electrons of atoms in the laser’s path. As the plot unfolded, a puzzle would be resolved - opening, he realized, a new frontier in the measurement of the ultrafast and the ultrabrief.

  • Optics made to measure

    Optics made to measure

    There is something unique about the startup company UltraFast Innovations. The company, which designs and manufactures tailor-made optics for ultrafast applications, was set up by two academic giants in the field of ultrafast optics research — the Ludwig-Maximilians-Universität München (LMU) and the Max Planck Institute of Quantum Optics (MPQ), both based in Garching, Germany. These organizations have both spun-out companies before, but this one is different — this one they own. Unlike other spin-offs, where researchers set up their own company and licence technology from their university or institute for a small stake in the company, UltraFast Innovations is owned 50:50 by LMU and MPQ. Nadya Anscombe finds out about the company’s products and its plans for the future.

  • Europe leads the way in attosecond research

    Europe leads the way in attosecond research

    Breaking the 100 as barrier and making the first movie of electron motion are just two recent milestones achieved by European researchers. Nadya Anscombe talks to key players in the attosecond community to see what the future holds: Scientists all over the world have for many years been trying to build a camera that works on this timescale. Being able to see electronic motion in real time would open up a whole new field of science and would revolutionize the way that we see the world. Just a few years ago, scientists could only dream of such a technology, but today the impossible become reality.

  • Attosecond pulses: Light to reveal electrons interacting within atoms

    Attosecond pulses: Light to reveal electrons interacting within atoms

    By carefully controlling the waveform of an ultrafast laser pulse and sending it through a jet of neon gas, briefly ionizing it, researchers at the Max-Planck-Institut für Quantenoptik (MPQ; Garching, Germany), the Ludwig-Maxmilians-Universität München (also in Garching), and the Lawrence Berkeley National Laboratory (Berkeley, CA) have created the shortest light pulse yet only 80 attoseconds (as) in duration. Such well-controlled photoionization will result in new science, for example by allowing direct observation of quantum-electronic correlations writes John Wallace in a featured article.

  • Watching what happens during attoseconds in solids

    Watching what happens during attoseconds in solids

    In pump/probe experiments, one pulse (of light, of x-rays, of electrons, etc.) triggers a process, and another pulse with an adjustable delay probes the subsequent temporal evolution of the process. This has turned out to be the most direct approach to time-domain investigations of fast-evolving microscopic processes, writes Dr. Reinhard Kienberger in this article. Accessing atomic and molecular inner-shell relaxation processes, valence-band electron wave packet dynamics, electron-electron interactions or atomic-scale charge transport in real time requires subfemtosecond temporal resolution. The emergence of intense waveform-controlled few-cycle near-infrared laser pulses and isolated subfemtosecond extreme-ultraviolet (XUV) pulses available for pump/probe experiments has opened the door for direct time-domain access to electron motion on the atomic (i.e., subnanometer) scale. These tools, along with the technique of laser-field controlled XUV photoemission, have permitted real-time observation of intra-atomic electronic motion in several proof-of-concept experiments performed on isolated atoms in the gas phase and mark the birth of attosecond science and time-resolved atomic transient recording.

  • Attosecond pulses probe electronics

    Attosecond pulses probe electronics

    In April 2007, physicists announced the attosecond-scale real-time measurement of the electron tunneling speed in neon gas using ultrashort light-pulse generation and control. Now, the attosecond envelope has again expanded with the measurement of the electron transport in a condensed-matter system—the first of its kind in a solid, according to an international research team led by Ferenc Krausz, professor of physics at the Ludwig-Maximillians-Universität München, and director of the Max-Planck-Institut für Quantenoptik (Garching, Germany). Science writer Valerie C. Coffey reports about this latest success.

  • Attosecond spectroscopy in condensed matter

    Attosecond spectroscopy in condensed matter

    Comprehensive knowledge of the dynamic behaviour of electrons in condensed-matter systems is pertinent to the development of many modern technologies, such as semiconductor and molecular electronics, optoelectronics, information processing and photovoltaics. Yet it remains challenging to probe electronic processes, many of which take place in the attosecond (1 as = 10−18 s) regime. In contrast, atomic motion occurs on the femtosecond (1 fs = 10−15s) timescale and has been mapped in solids in real time using femtosecond X-ray sources. Here we extend the attosecond techniques previously used to study isolated atoms in the gas phase to observe electron motion in condensed-matter systems and on surfaces in real time. We demonstrate our ability to obtain direct time-domain access to charge dynamics with attosecond resolution by probing photoelectron emission from single-crystal tungsten.

  • Attosecond control and measurement: lightwave electronics

    Attosecond control and measurement: lightwave electronics

    Electrons emit light, carry electric current, and bind atoms together to form molecules. Insight into and control of their atomic-scale motion are the key to understanding the functioning of biological systems, developing efficient sources of x-ray light, and speeding up electronics. Capturing and steering this electron motion require attosecond resolution and control, respectively (1 attosecond = 10−18 seconds). A recent revolution in technology has afforded these capabilities: Controlled light waves can steer electrons inside and around atoms, arking the birth of lightwave electronics. Isolated attosecond pulses, well reproduced and fully characterized, demonstrate the power of the new technology. Controlled few-cycle light waves and synchronized attosecond pulses constitute its key tools. We review the current state of lightwave electronics and highlight some future directions.

  • Die ganze Physik zum 21. Jahrhundert

    Die ganze Physik zum 21. Jahrhundert

    Editor D. Meschede released the 23. Volume of the encyclopedia Gerthsen Physik. The 23rd edition consisted of 1162 pages, contained 94 tables, 105 calculated examples and 1074 exercises with solutions as well as a CD-ROM with 30 animations to visualize the theory of relativity. As part of the "Einstein Year 2005", the chapter on relativity in particular was revised and presented in a timely manner (over long stretches with four-vectors). The entire compendium including exercises in full text is available online at many university libraries.

  • Welcome to attoworld

    Welcome to attoworld

    The dial on your kitchen scales spins when a virus lands. The clock on the wall has gone berserk, ticking every billionth of a billionth of a second. Your camera flashes so fast that it captures single molecules in freeze-frame. Prepare to enter attoworld, the ultra-small realm so foreign that no one quite knows what’s going on. Today’s scientists are inventing gadgets that can measure attoscale quantities, such as the mass of a virus, which is just a few attograms. They can sense attonewton forces so feeble they couldn’t lift a protein molecule. And they are designing attosecond stopwatches and attolitre test tubes. Hazel Muir zooms in new inventions finding their vocation in the head-swimmingly small attoworld.

  • Ultrashort laser pulses beget even shorter bursts in the extreme ultraviolet

    Ultrashort laser pulses beget even shorter bursts in the extreme ultraviolet

    The attophysics frontier is about to expand, thanks to the newly won ability to control the phase of amplified laser pulses. Science writer Charles Day reports about Ferenc Krausz of the Vienna University of Technology, Austria, and Theodor Hänsch of the Max Planck Institute for Quantum Optics in Garching, just north of Munich, Germany. The scientists are now able make isolated pulses of precisely controlled and reproducible shape that last a few hundred attoseconds. 

  • Time-resolved atomic inner-shell spectroscopy

    Time-resolved atomic inner-shell spectroscopy

    The characteristic time constants of the relaxation dynamics of core-excited atoms have hitherto been inferred from the linewidths of electronic transitions measured by continuous-wave extreme ultraviolet or X-ray spectroscopy. M. Drescher and co-workers demonstrate that a laser-based sampling system, consisting of a few-femtosecond visible light pulse and a synchronized sub-femtosecond soft X-ray pulse, allows us to trace these dynamics directly in the time domain with attosecond resolution. report about their experiments. The team has measured a lifetime of 7.9+1.0−0,9 fs of M-shell vacancies of krypton in such a pumpprobe experiment.

  • Optical pulses reach attosecond length

    Optical pulses reach attosecond length

    In the world of ultrashort optical pulses, the femtosecond (fs) has been superseded by the attosecond (as, or 10−18 s). An international collaboration of ten scientists claims to have generated and detected isolated soft x-ray pulses of 650-as duration. Scientists at the Vienna University of Technology, Austria, along with others at the National Research Centre (Ottawa, Canada) and the University of Bielefeld, Germany, have developed experimental tools and techniques that could enable attosecond-resolution spectroscopy of bound electron dynamics in atoms and molecules.

  • Intense few-cycle laser fields: frontiers of nonlinear optics

    Intense few-cycle laser fields: frontiers of nonlinear optics

    The rise time of intense radiation determines the maximum field strength atoms can be exposed to before their polarizability dramatically drops due to the detachment of an outer electron. Recent progress in ultrafast optics has allowed the generation of ultraintense light pulses comprising merely a few field oscillation cycles. The arising intensity gradient allows electrons to survive in their bound atomic state up to external field strengths many times higher than the binding Coulomb field and gives rise to ionization rates comparable to the light frequency, resulting in a significant extension of the frontiers of nonlinear optics and (nonrelativistic) high-field physics. Implications include the generation of coherent harmonic radiation up to kiloelectronvolt photon energies and control of the atomic dipole moment on a subfemtosecond time scale. In this review Ferenc Krausz and Thomas Brabec present the landmarks of the 30-odd-year evolution of ultrashort-pulse laser physics and technology culminating in the generation of intense few-cycle light pulses and discusses the impact of these pulses on high-field physics.

  • Extreme nonlinear optics. Exposing matter to a few periods of light

    Extreme nonlinear optics. Exposing matter to a few periods of light

    Intense light pulses in the single-cycle regime have opened up new avenues in linear optics. These, along with expected impacts on other areas of science and technology, are discussed by F. Krausz, T. Brabec, M Schnürer, and C.Spielmann. Ultrashort-pulse laser technology has progressed tremendously over the last 10 years. The invention of a new broad-band laser medium, titanium-doped sapphire, a novel ultrafast mode-locking technique dubbed Kerr-lens mode-locking, and a powerful device for ultrabroad-band dispersion control – chirped multilayer mirrors – for the first time opened the way to a reliable sub-10-fs laser technology. Drawing on the concept of chirped-pulse amplification, Ti:sapphire laser systems are now capable of generation pulses of around 20 fs in duration with millijoule energies (yielding peak powers on the order of hundreds of gigawatt) at 1-kHz repetition rates, and well beyond 100 ml (resulting in multi-terawatt peak powers, 1TW = 1012 W) in the 10-Hz regime.

  • Chirped dielectric mirrors improve Ti:sapphire lasers

    Chirped dielectric mirrors improve Ti:sapphire lasers

    High-quality seed pulses from mirror-dispersion-controlled Ti:sapphire system allow chirped pulse amplification without a pulse stretcher. Ch.Spielmann, M. Lenzner, F.Krausz, R.Szipöcs and K. Ferencz report about the future of Ti:sapphire laser-systems: The invention of Ti:sapphire and its development to a top-quality laser crystal, together with the appearance of novel techniques for laser modelocking and dispersion compensation, have revolutionized ultrafast laser technology. Now chirped mirrors dielectric mirrors offer the potential of even shorter pulses and may make turnkey ultrafast Ti:sapphire systems a reality.

  • Faster than the speed of light

    Faster than the speed of light

    Quantum mechanics have been with us for over sixty years and has been thoroughly put through its paces both experimentally and theoretically. Yet physicists continue to be haunted by its strange implications virtual particles, antimatter, negative energy, Schrödingers cat. Now it appears there is something else to add to the list: light that travels faster than light.