be a key element in the control of multiphoton quantum states, with a wide range of applications in entanglement - based quantum communication and quantum information processing. quantum technologies with photons quantum technologies aim to exploit the unique properties of quantum mechanics, the physics theory that explains how the world works at very small scales. for example a quantum computer relies on the fact that quantum particles, such as photons, can exist in a " superposition " of two states at the same time - in stark contrast to the transistors in a pc which can only be in the state " 0 " or " 1 ". photons are an excellent choice for quantum technologies because they are relatively noise - free ; information can be moved around quickly - at the speed of light ; and manipulating single photons is easy. making two photons " talk " to each other to realise the all - important controlled - not gate is much harder, but professor o ' brien and his colleagues at the university of queensland demonstrated this back in 2003 [ nature 426, 264 ]. last year, professor o ' brien ' s centre for quantum photonics at bristol showed how such interactions between photons could be realised on a silicon chip, pointing the way to advanced quantum technologies based on photons [ science 320, 646 ]. photons are also required to " talk " to each other to realise the ultra - precise measurements that harness the laws of quantum mechanics - quantum metrology. in 2007 professor o ' brien and the same japanese collaborators reported such a quantum metrology measurement with four photons [ science 316, 726 ]. the work was supported by the epsrc, and japanese funding agencies. other social bookmarking and sharing tools : note : if no author is given, the source is cited instead.


what you need superconductors are very bizarre materials at room temperature they behave like a normal metal or ceramic, electrically or in any other way, when they are cooled below their critical temperature ( tc ) their resistance entirely disappears to zero. possibly the most beautiful and accessable result of this is magnetic levitation. what is going on? if you more a conductor towards a magnet you change the amount of magnetic flux in the conductor so you induce a circulating current in a conductor. this current produces a magnetic field which acts against the movement, just like in the magnet dropping down a pipe experiment. if the conductor has no resistance ( its a superconductor ) the current will never die away, so the superconductor will repel the magnet and levitate. if the superconductor was perfect it would always be repelled by a magnet, however high temperature superconductors, which work at 77k ( - 196°c ) or higher will allow magnetic flux into them if they are cooled in the flux or if you apply a large enough force. this flux gets pinned on slightly weaker parts of the superconductor. the superconductor is now an electromagnet, but it will still resist movements of the magnet, so now instead of just repelling, it is locked in one position over the magnet. this is why the superconductor didn ' t fall off when it was turned upside down. boeing is trying to use this effect to make superconducting bearings which in a vacuum will have far lower friction than a mechanical bearing, so they can build large flywheels to store excess electricity when the demand is low and return it when the demand is high, using a superconducting bearing the time the energy can be stored is measured in weeks not hours with a conventional bearing. david cardwell who demonstrated the levitation to us is also using this effect to produce large superconducting magnets using this effect which can be used for gp surgery mri machines instead of the more expensive low temperature superconducting magnets which require liquid helium to cool them. superconductivity have many other uses, as power cables, large magnets, sensors etc. find out more in " the history of superconductors " article what to do what may happen why does it happen?


laser therapy is any treatment using intense beams of light to precisely cut, burn, or destroy tissue. the term laser is an acronym for " light amplification by stimulated emission of radiation. " the laser light beam comes from radiation sources so small and safe that it poses no health risks to the patient or medical team. lasers can be used for many medical purposes. because the laser beam is so small and precise, it allows doctors to safely treat tissue without injuring the surrounding area. lasers may be used to remove growths or cauterize lasers may also be used during the following procedures : garrett cg, ossoff rh, reinisch l. laser surgery : basic principles and safety considerations. in : cummings cw, flint pw, haughey bh, et al, eds. otolaryngology : head & neck surgery. 5th ed. philadelphia, pa : mosby elsevier ; 2010 : chap 3. linda j. vorvick, md, medical director and director of didactic curriculum, medex northwest division of physician assistant studies, department of family medicine, uw medicine, school of medicine, university of washington. also reviewed by david zieve, md, mha, medical director, a. d. a. m. health solutions, ebix, inc.