Lightsabers, the famous signature weapon of the Jedi order and their Sith counterparts, have always fascinated the fans, from Yoda’s green saber to Darth Maul’s double-bladed lightsaber or Kylo Ren’s crossguard one.
“Long ago in forgotten times, when the Sith and Jedi fought for control of the Galaxy, weapons there were, of unimaginable power. Always at their heart, a kyber crystal was.” – Yoda
The lightsaber contains a Force-attuned crystal from the planet Ilum. The Sith discovered that they could create red artificial crystals energized by the dark side of the Force.
But how does it really look in 2015?
In order to cut any kind of material, the temperature of the blade would need to rise up to 20 000 K. A recent project “Apollon” is close to making the most powerful laser reaching 5×1015 W by using a hybrid architecture based on the OPCPA technology (Optical Parametric Chirped-pulse Amplification). The problem is that the fundamental properties of light derives from its constituent particles – massless quanta (photons) that do not interact with each other as it would do in the movies. Two laser sabers would pass through each other, except if you could allow the photons to interact as they would have a mass. IMPOSSIBLE! This was actually the last achievement of a research team from the Massachusetts Institute of Technology, which realized coherent interactions between individual photons by using a quantum nonlinear medium, inside which individual photons pair up and travel as massive particles with a strong mutual attraction. Crazy! But still, wouldn’t the laser be too long? Like infinitely long? If only it would be possible to stop the light… Just ask for it! In 2001, Pr. Hau from Harvard was able to stop light completely by using a small cloud of ultra cooled atoms suspended magnetically in a chamber pumped down to a vacuum. But even more recently, researchers at Darmstadt Technical University achieved trapping light for one minute in a crystal with the so called technology, Electromagnetically Induced Transparency. But let’s be honest, these amazing achievements which to manipulate light are so far only applicable for low energy telecommunication and computer science but the possibilities are huge! Quantum computer, unbreakable encryption…
The most likely technology that could be used for building the lightsaber would be a plasma jet. Plasma is considered as the 4th state of matter. Simply described, plasma is a gas of electrically-charged particles. It is today a wide spread technology that allows us to cut off thick pieces of steel up to 120 mm. The important issue remains however of the control of this high heated plasma due to its specific properties. In fact, this is part of one of the most important issue of our modern society: the control of atomic fusion which in that field, Europe has been at the forefront of this experimental research on plasma physics through major programs such as the Joint European Torus (JET). The project ITER is attempting to control the plasma resulting of fusion reaction with a magnetic confinement in a system named Tokamak. The magnetic fields are generated by superconducting magnetic field coils located around the plasma reactor chamber and by electrical currents flowing in the plasma itself. On 10 December 2015, the German team of the Max Planck Institute for Plasma Physics realized their first experimental fusion reaction with a helium plasma in a Stellarator, an alternative device for controlling plasma. Nevertheless the experience only lasted a tenth of a second. I guess, not long enough to defeat Darth Vador in a lightsaber fight!
“Powerful plasma controlled in a powerful magnetic field”, can we provide as much energy in a handle to run it on? Would the Jedi have the same battery issue as the modern man with his smartphone? Wel, actually he uses the Force… The storage of energy is today a very hot topic at almost all levels of our modern life. For the automotive industry, it is an essential point that prevents the electrical transition. The common technology relies on chemical reactions for storage with Lithium-Ion battery, but recent researches has led to new Lithium-Oxygene or Aluminium-Ion batteries allowing more cycles, more energy stored and a quicker charge. Another high potential technology studied at the Massachussets Institute of Technology is based on nanotechnology with the concept of thermopower waves. A nanowire with large axial thermal diffusivity can accelerate a self-propagating reaction wave using a fuel coated along its length. The reaction wave drives electrical carriers in a thermopower wave, creating a high-powered pulse of as much as 7 kW/kg in experiments using carbon nanotubes.
Even if we are close to reaching the characteristic of a lightsaber, we are very far from having it lightly hanging at our hip. Let’s keep searching. May the Force be with us!
Jean-Gaël Try, R&D Consultant, Leyton Belgium
 Star Wars : Episode I – The Phantom Menace
 Star Wars : Episode VII – The Force Awakens
 APOLLON Project from the Laboratoire pour l’Utilisation des Lasers Intenses (LULI)
 « Attractive photons in a quantum nonlinear medium », Ofer Firstenberg et al, 2013
 « Frozen light », Scientific American, Hau L. V., 17 July 2001
 « Stopped Light and Image Storage by Electromagnetically Induced Transparency up to the Regime of One Minute », Georg Heinze, Christian Hubrich, and Thomas Halfmann, 15 July 2013
 International Thermonuclear Experimental Reactor http://www.ipp.mpg.de/3984226/12_15
 International Thermonuclear Experimental Reactor
 « Cycling Li-O2 batteries via LiOH formation and decomposition », Tao Liu et al, 30 October 2015
 « An ultrafast rechargeable aluminium-ion battery »,Hongjie Dai et al, 6 April 2015
 « Carbon nanotube-guided thermopower waves », M.S. Stranoa, October 2010