Quantum lasers: Half light, half matter
来源：未知 作者：申帅 时间：2019-03-14 02:02:01
By Richard Webb Lasers might be pushing 50, but they are still the youthful pin-ups of fundamental physics. Since the first one was unveiled in 1960, the more apocalyptic predictions of how they might be used – as death rays, for example – have proved to be overblown. Their peaceful application, on the other hand, can be seen everywhere from cutting and welding to combating cancer and cataracts, to powering telecoms and consumer electronics, and has mushroomed into an industry worth $6 billion in 2007. Advances in the laser lab translate into gadgets in our homes at astonishing speed: think of the progression from CD to DVD and now Blu-ray technology in just a few decades. So here’s a heads-up for you: we could be about to witness the next stage in the laser’s evolution, a sea change in how laser light is produced. A new wave of devices looks likely to exploit particle-like packets of energy to produce their light – packets that are neither light, nor matter, but both. It’s early days, but advances in taming these exotic beasts are proceeding apace. “I keep expecting progress to end,” says physicist Jeremy Baumberg at the University of Cambridge, one of the pioneers. “But it just keeps going.” The pay-offs could be immense: not just lasers that use less juice than ever before and new low-power lighting technology but maybe even a way to make the semi-mythical, superpowerful quantum computer. What is this new item in the physicist’s armoury? The polariton, or exciton polariton, to give it its full name. How can such a particle be light and matter simultaneously?