Maglev trains work using the principles of superconducting magnets. Japan's maglev hold the world record of being the fastest train at 600 kmph. It is still in testing phase (on a test track of 42.8km in Yamanashi prefecture) and when it opens to public it will have an operational speed of 500 kmph. Thus a journey from Tokyo to Nagoya will only take 40mins (and hour less than the current Tokaido Shinkansen).