大学考试|英美报刊节选翻译训练(十九)

From One qubit at a time 摘自《经济学人》 May 4th 2006

COMPUTING^{1 is about to hit a problem. （1）In each new generation the components2 are smaller than they were in its predecessor3, and the speed at which this miniaturisation is happening means that within 15 years or so a fundamental limit will be reached.At that point, not only will the strange effects of quantum mechanics hold sway, the components themselves will be on the scale of atoms and no further size-reduction will be possible. Which is why scientists and engineers are seeking new ways of building computers.}

One route they are exploring, which was discussed at a meeting held recently at the Royal Society in London, is called quantum computing. Instead of trying to overcome quantum weirdness^{4, this technique embraces and exploits it. （2）The thing that distinguishes a quantum computer from the sort in use today is the number of calculations it can do in parallel.Both sorts of computer use binary5 arithmetic, but they do so in rather different ways. A classical computer employs bitsbinary digits6, either zero or oneto process and store information. But a bit must be one or the other; it cannot be both at the same time. A quantum computer does not suffer from this restriction7.}

new words

miniaturisationn. 小型化
小知识： Quantum Computer 量子计算机

量子计算机是一种机器，像猜想的那样，基于亚原子级的微粒行为实行运算。如此的计算机，一旦被开发出来，可以比以前的计算机每秒多实行数百万条指令。处置能的指数级提升是因为数据单元在量子计算机中，可以同时存在几种状况，这一点与二进制计算机不同。某种意义上，机器可同时进行几个思维的考虑，各种思维虽然同时产生于同样的颗粒集，但他们之间是相互独立的。

工程师创造了术语qubit来表示量子计算机的基本数据单元。一个qubit实质上是一个位（二进制数字），它可以同时呈现一个或多个值。这个理论和量子机制理论同样奇怪，在这个理论中单独的微粒可以存在于多个地方上。一种考虑qubit可以同时存在于多个状况的方法是设想它有多个面或维，每个面或维都可以高（罗辑1）或低（罗辑0）。因此假如一个qubit有两个面，它就有四个同时存在的独立状况（00、01、10、11）；假如它有三个面，就有八个可能的状况，二机制表示为000直到111，依次类推。

量子计算机在以下应用中是很有用的：

◆破获密码◆统计剖析◆大数相乘◆在理论物理学中解决问题
◆解决很多变量的最佳化问题

研究开发工程师所遇见的主要困难是要使微粒在肯定的时间内以适合的方法动作是极其难得。最轻微的干扰将使机器停止量子方法的工作转而工作在传统模式下。扩散的电磁场，物理移动，甚至极小的电子干扰都将打乱处置进程。