Multiple-Photon Resonance Enabled Quantum Interference in Emission Spectroscopy of N2+

Quantum interference occurs frequently in the interaction of laser radiation with materials,leading to a series of fascinating effects such as lasing without inversion,electromagnetically induced transparency,Fano resonance,etc.Such quantum interference effects are mostly enabled by single-photon resonance with transitions in the matter,regardless of how many optical frequencies are involved.Here,we report on quantum interference driven by multiple photons in the emission spectroscopy of nitrogen ions that are resonantly pumped by ultrafast infrared laser pulses.In the spectral domain,Fano resonance is observed in the emission spectrum,where a laser-assisted dynamic Stark effect creates the continuum.In the time domain,the fast-evolving emission is measured,revealing the nature of free-induction decay arising from quantum radiation and molecular cooperativity.These findings clarify the mechanism of coherent emission of nitrogen ions pumped with mid-infrared pump laser and are found to be universal.The present work opens a route to explore the important role of quantum interference during the interaction of intense laser pulses with materials near multiple photon resonance.

Future for inertial-fusion energy in Europe:a roadmap

The recent achievement of fusion ignition with laser-driven technologies at the National Ignition Facility sets a historic accomplishment in fusion energy research.This accomplishment paves the way for using laser inertial fusion as a viable approach for future energy production.Europe has a unique opportunity to empower research in this field internationally,and the scientific community is eager to engage in this journey.We propose establishing a European programme on inertial-fusion energy with the mission to demonstrate laser-driven ignition in the direct-drive scheme and to develop pathway technologies for the commercial fusion reactor.The proposed roadmap is based on four complementary axes:(ⅰ)the physics of laser-plasma interaction and burning plasmas;(ⅱ)high-energy high repetition rate laser technology;(ⅲ)fusion reactor technology and materials;and(ⅳ)reinforcement of the laser fusion community by international education and training programmes.We foresee collaboration with universities,research centres and industry and establishing joint activities with the private sector involved in laser fusion.This project aims to stimulate a broad range of high-profile industrial developments in laser,plasma and radiation technologies along with the expected high-level socio-economic impact.

Innovative Education and Training in high power laser plasmas(PowerLaPs) for plasma physics, high power laser-matter interactions and high energy density physics-theory and experiments

The Erasmus Plus programme’Innovative Education and Training in high power laser plasmas’,otherwise known as PowerLaPs,is described.The PowerLaPs programme employs an innovative paradigm in that it is a multi-centre programme where teaching takes place in five separate institutes with a range of different aims and styles of delivery.The ’in class’ time is limited to four weeks a year,and the programme spans two years.PowerLaPs aims to train students from across Europe in theoretical,applied and laboratory skills relevant to the pursuit of research in laserplasma interaction physics and inertial confinement fusion(ICF).Lectures are intermingled with laboratory sessions and continuous assessment activities.The programme,which is led by workers from the Technological Educational Institute(TEI)of Crete,and supported by co-workers from the Queen’s University Belfast,the University of Bordeaux,the Czech Technical-University in Prague,Ecole Polytechnique,the University of Ioannina,the University of Salamanca and the University of York,has just completed its first year.Thus far three Learning Teaching Training(LTT)activities have been held,at the Queen’s University Belfast,the University of Bordeaux and the Centre for Plasma Physics and Lasers(CPPL)of TEI Crete.The last of these was a two-week long Intensive Programme(IP),while the activities at the other two universities were each five days in length.Thus far work has concentrated upon training in both theoretical and experimental work in plasma physics,high power laser-matter interactions and high energy density physics.The nature of the programme will be described in detail and some metrics relating to the activities carried out to date will be presented.