量子计算机单光子管理机制得以完善
文章来源:未知 文章作者:enread 发布时间:2011-01-21 05:44 字体: [ ]  进入论坛
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The quantum computers of tomorrow might use photons, or particles of light, to move around the data they need to make calculations, but photons are tricky1(狡猾的) to work with. Two new papers by researchers working at the National Institute of Standards and Technology (NIST) have brought science closer to creating reliable sources of photons for these long-heralded devices. In principle, quantum computers can perform calculations that are impossible or impractical3 using conventional computers by taking advantage of the peculiar4(特殊的,独特的) rules of quantum mechanics. To do this, they need to operate on things that can be manipulated into specific quantum states. Photons are among the leading contenders(竞争者) .

The new NIST papers address one of the many challenges to a practical quantum computer: the need for a device that produces photons in ready quantities, but only one at a time, and only when the computer's processor is ready to receive them. Just as garbled5(篡改的,混乱的) data will confuse a standard computer, an information-bearing photon that enters a quantum processor together with other particles—or when the processor is not expecting it—can ruin a calculation.

The single-photon source has been elusive6(难懂的,易忘的) for nearly two decades, in part because no method of producing these particles individually is ideal. "It's a bit like playing a game of whack-a-mole, where solving one problem creates others," says Alan Migdall of NIST's Optical Technology Division. "The best you can do is keep all the issues under control somewhat. You can never get rid of them."

The team's first paper addresses the need to be certain that a photon is indeed coming when the processor is expecting it, and that none show up unexpected. Many kinds of single-photon sources create a pair of photons and send one of them to a detector7, which tips off the processor to the fact that the second, information-bearing photon is on its way. But since detectors8 are not completely accurate, sometimes they miss the "herald2" photon—and its twin zips into the processor, gumming up the works.

The team effort, in collaboration9 with researchers from the Italian metrology(度量衡) laboratory L'Istituto Nazionale di Ricerca Metrologica (INRIM), handled the issue by building a simple gate into the source. When a herald photon reaches the detector, the gate opens, allowing the second photon past. "You get a photon when you expect one, and you don't get one when you don't," Migdall says. "It was an obvious solution; others proposed it long ago, we were just the first ones to build it. It makes the single photon source better."

In a second paper, the NIST team describes a photon source to address two other requirements. Quantum computers will need many such sources working in parallel, so sources must be able to be built in large numbers and operate reliably; and so that the computer can tell the photons apart, the sources must create multiple individual photons, but all at different wavelengths10. The team outlines a way to create just such a source out of silicon11, which has been well-understood by the electronics industry for decades as the material from which standard computer chips are built.

"Ordinarily a particular material can produce only pairs in a specific pair of wavelengths, but our design allows production of photons at a number of regular and distinct wavelengths simultaneously12, all from one source," Migdall says. "Because the design is compatible with microfabrication(精密加工) techniques, this accomplishment13 is the first step in the process of creating sources that are part of integrated circuits, not just prototype computers that work in the hothouse of the lab."



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1 tricky 9fCzyd     
adj.狡猾的,奸诈的;(工作等)棘手的,微妙的
参考例句:
  • I'm in a rather tricky position.Can you help me out?我的处境很棘手,你能帮我吗?
  • He avoided this tricky question and talked in generalities.他回避了这个非常微妙的问题,只做了个笼统的表述。
2 herald qdCzd     
vt.预示...的来临,预告,宣布,欢迎
参考例句:
  • In England, the cuckoo is the herald of spring.在英国杜鹃鸟是报春的使者。
  • Dawn is the herald of day.曙光是白昼的先驱。
3 impractical 49Ixs     
adj.不现实的,不实用的,不切实际的
参考例句:
  • He was hopelessly impractical when it came to planning new projects.一到规划新项目,他就完全没有了实际操作的能力。
  • An entirely rigid system is impractical.一套完全死板的体制是不实际的。
4 peculiar cinyo     
adj.古怪的,异常的;特殊的,特有的
参考例句:
  • He walks in a peculiar fashion.他走路的样子很奇特。
  • He looked at me with a very peculiar expression.他用一种很奇怪的表情看着我。
5 garbled ssvzFv     
adj.(指信息)混乱的,引起误解的v.对(事实)歪曲,对(文章等)断章取义,窜改( garble的过去式和过去分词 )
参考例句:
  • He gave a garbled account of what had happened. 他对所发生事情的叙述含混不清。
  • The Coastguard needs to decipher garbled messages in a few minutes. 海岸警卫队需要在几分钟内解读这些含混不清的信息。 来自辞典例句
6 elusive d8vyH     
adj.难以表达(捉摸)的;令人困惑的;逃避的
参考例句:
  • Try to catch the elusive charm of the original in translation.翻译时设法把握住原文中难以捉摸的风韵。
  • Interpol have searched all the corners of the earth for the elusive hijackers.国际刑警组织已在世界各地搜查在逃的飞机劫持者。
7 detector svnxk     
n.发觉者,探测器
参考例句:
  • The detector is housed in a streamlined cylindrical container.探测器安装在流线型圆柱形容器内。
  • Please walk through the metal detector.请走过金属检测器。
8 detectors bff80b364ed19e1821aa038fae38df83     
探测器( detector的名词复数 )
参考例句:
  • The report advocated that all buildings be fitted with smoke detectors. 报告主张所有的建筑物都应安装烟火探测器。
  • This is heady wine for experimenters using these neutrino detectors. 对于使用中微子探测器的实验工作者,这是令人兴奋的美酒。 来自英汉非文学 - 科技
9 collaboration bW7yD     
n.合作,协作;勾结
参考例句:
  • The two companies are working in close collaboration each other.这两家公司密切合作。
  • He was shot for collaboration with the enemy.他因通敌而被枪毙了。
10 wavelengths 55c7c1db2849f4af018e7824d42c3ff2     
n.波长( wavelength的名词复数 );具有相同的/不同的思路;合拍;不合拍
参考例句:
  • I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话,因为我们俩完全不对路。 来自《简明英汉词典》
  • Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句
11 silicon dykwJ     
n.硅(旧名矽)
参考例句:
  • This company pioneered the use of silicon chip.这家公司开创了使用硅片的方法。
  • A chip is a piece of silicon about the size of a postage stamp.芯片就是一枚邮票大小的硅片。
12 simultaneously 4iBz1o     
adv.同时发生地,同时进行地
参考例句:
  • The radar beam can track a number of targets almost simultaneously.雷达波几乎可以同时追着多个目标。
  • The Windows allow a computer user to execute multiple programs simultaneously.Windows允许计算机用户同时运行多个程序。
13 accomplishment 2Jkyo     
n.完成,成就,(pl.)造诣,技能
参考例句:
  • The series of paintings is quite an accomplishment.这一系列的绘画真是了不起的成就。
  • Money will be crucial to the accomplishment of our objectives.要实现我们的目标,钱是至关重要的。
TAG标签: quantum computers photons
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