一月 16

翻译 How Quantum Computers Work

量子计算机是如何工作的?

本文翻译自 http://computer.howstuffworks.com/quantum-computer.htm

The massive amount of processing power generated by computer manufacturers has not yet been able to quench our thirst for speed and computing capacity. In 1947, American computer engineer Howard Aikensaid that just six electronic digital computers would satisfy the computing needs of the United States. Others have made similar errant predictions about the amount of computing power that would support our growing technological needs. Of course, Aiken didn't count on the large amounts of data generated by scientific research, the proliferation of personal computers or the emergence of the Internet, which have only fueled our need for more, more and more computing power.
由计算机制造商带来的巨大的处理能力并没有让我们对速度和计算能力的渴望停止。1947年,美国的计算机工程师Howard Aiken曾说过仅仅六台电子数字计算机就能够满足整个美国的需要。其他人有过类似的仅几台计算机就能满足日益增长的科学技术的需要的偏离实际的看法。当然,Aiken的估计没有考虑到由科学研究产生的巨量数据、个人计算机的剧增或是因特网的出现——这些的出现让我们需要更多,更多,更多的计算能力。

Will we ever have the amount of computing power we need or want? If, asMoore's Law states, the number of transistors on a microprocessor continues to double every 18 months, the year 2020 or 2030 will find the circuits on a microprocessor measured on an atomic scale. And the logical next step will be to create quantum computers, which will harness the power of atoms and molecules to perform memory and processing tasks. Quantum computers have the potential to perform certain calculations significantly faster than any silicon-based computer.
我们能够永远得到我们需要或想要的计算能力吗?如果像摩尔定律所说的那样,微处理器的晶体管数目每18个月翻一番,到2020年或2030年微处理器上的电路将会达到原子大小,所以合乎逻辑的下一步将是制造利用原子和分子的力量实现存储和计算的量子计算机。量子计算机有比基于硅的传统计算机在计算能力方面强得多的潜力。

Scientists have already built basic quantum computers that can perform certain calculations; but a practical quantum computer is still years away. In this article, you'll learn what a quantum computer is and just what it'll be used for in the next era of computing.
科学家已经制造出了基本的能够执行确定计算的量子计算机,但是实用性的量子计算机离我们仍很远。在这篇文章里,你将了解到什么是量子计算机和在下一个计算时代它能够被用来做什么。

You don't have to go back too far to find the origins of quantum computing. While computers have been around for the majority of the 20th century, quantum computing was first theorized less than 30 years ago, by a physicist at the Argonne National Laboratory. Paul Benioff is credited with first applying quantum theory to computers in 1981. Benioff theorized about creating a quantum Turing machine. Most digital computers, like the one you are using to read this article, are based on the Turing Theory. Learn what this is in the next section.

对于量子计算机的起源你不需要追溯太远。当计算机驰骋于20世纪的大部分时间时,距量子计算机的理论构想被一个美国阿贡国家实验室的物理学家首次提出还不到30年。 Paul Benioff被认为在1981年首次将量子理论应用于计算机。Benioff 建立了一个有关量子图灵机的理论。大多数的数字计算机,比如你正在使用的读这篇文章的计算机,都是基于图灵理论的。下一部分将学习到这是什么。

Defining the Quantum Computer                                                                                                                           定义量子计算机

The Turing machine, developed by Alan Turing in the 1930s, is a theoretical device that consists of tape of unlimited length that is divided into little squares. Each square can either hold a symbol (1 or 0) or be left blank. A read-write device reads these symbols and blanks, which gives the machine its instructions to perform a certain program. Does this sound familiar? Well, in a quantum Turing machine, the difference is that the tape exists in a quantum state, as does the read-write head. This means that the symbols on the tape can be either 0 or 1 or a superposition of 0 and 1; in other words the symbols are both 0 and 1 (and all points in between) at the same time. While a normal Turing machine can only perform one calculation at a time, a quantum Turing machine can perform many calculations at once.
由阿兰·图灵创造于20世界30年代的图灵机是一个理想中的由无限长的纸带组成的装置。纸带被分成小正方形,每一个正方形要么被赋予一个符号(1或0)要么是空白。一个读写装置读入这个符号或空白,告诉机器下一步如何工作。这听起来很熟悉吧?嗯,在量子图灵机中,区别就在于纸带是一量子状态形式存在的,读写头也如此。这意味着在纸带上的符号可以是1或0或是1和0的叠加,换言之,符号可以同时是1和0。一个普通的图灵机一次只能进行一次计算,而量子图灵机则能一次进行多次计算。

Today's computers, like a Turing machine, work by manipulating bits that exist in one of two states: a 0 or a 1. Quantum computers aren't limited to two states; they encode information as quantum bits, or qubits, which can exist in superposition. Qubits represent atoms, ions, photons or electrons and their respective control devices that are working together to act as computer memory and a processor. Because a quantum computer can contain these multiple states simultaneously, it has the potential to be millions of times more powerful than today's most powerful supercomputers.
当今的计算机,比如图灵机,工作的原理基于操作存在的两种状态位:0和1.量子计算机不局限于两种状态:它将信息编码成能够处于叠加态的量子位,或量子比特。量子比特代表原子、离子、光子或电子和他们各自的控制装置。这些装置一起工作作为计算机内存和处理器。因为一台量子计算机能够同时包含这些状态,所以它有巨大的潜力能够比当今最强大的超级计算机还强大百万倍。

This superposition of qubits is what gives quantum computers their inherent parallelism. According to physicist David Deutsch, this parallelism allows a quantum computer to work on a million computations at once, while your desktop PC works on one. A 30-qubit quantum computer would equal the processing power of a conventional computer that could run at 10 teraflops (trillions of floating-point operations per second). Today's typical desktop computers run at speeds measured in gigaflops (billions of floating-point operations per second).
量子位的叠加态带给量子计算机与生俱来的并行性。据物理学家 David Deutsch说,这种并行性能够允许量子计算机一次进行百万次的计算,而你使用的计算机一次只能进行一次计算。一台30量子比特位的量子计算机的计算能力可以与一台10teralops(一万亿次浮点运算每秒)的传统计算机相当。当今典型的桌面电脑的运算能力以gigaflops(百亿次浮点运算每秒)来衡量。

Quantum computers also utilize another aspect of quantum mechanics known as entanglement. One problem with the idea of quantum computers is that if you try to look at the subatomic particles, you could bump them, and thereby change their value. If you look at a qubit in superposition to determine its value, the qubit will assume the value of either 0 or 1, but not both (effectively turning your spiffy quantum computer into a mundane digital computer). To make a practical quantum computer, scientists have to devise ways of making measurements indirectly to preserve the system's integrity. Entanglement provides a potential answer. In quantum physics, if you apply an outside force to two atoms, it can cause them to become entangled, and the second atom can take on the properties of the first atom. So if left alone, an atom will spin in all directions. The instant it is disturbed it chooses one spin, or one value; and at the same time, the second entangled atom will choose an opposite spin, or value. This allows scientists to know the value of the qubits without actually looking at them.
量子计算机也利用量子力学中另一原理——量子纠缠。量子计算机存在的一个问题就是当你观察亚原子粒子时,你可能会干扰它,并改变它的状态。如果你观察一个处于叠加态的量子位时,它会呈现出1或0,而不是1和0(这使你的出色的量子计算机变成普通的数字计算机)。为了制造一个有使用价值的量子计算机,科学家们不得不设计间接测量的方法保护系统的完整性。量子纠缠提供了一个潜在的答案。在量子物理中,当两原子受到外力作用时,它们会处于纠缠态,第二个原子能够呈现第一个原子的特性。当只有一个粒子时,它的自旋处于所有方向。在被干扰的一瞬间它选择了一个自旋方向,或一个值,而与此同时,第二个处于纠缠态的粒子将选择相反的自旋或值。这允许科学家在不直接观测的情况下知晓量子位的值。

Next, we'll look at some recent advancements in the field of quantum computing.
接下来,我们将一起来回顾下量子计算领域最近的进展。

QUBIT CONTROL
控制量子位

Computer scientists control the microscopic particles that act as qubits in quantum computers by usingcontrol devices.
计算机科学家使用控制装置控制微观粒子作为量子计算机的量子比特。

Ion traps use optical or magnetic fields (or a combination of both) to trap ions.
离子阱:使用光场或磁场(或结合两者)俘获离子。

Optical traps use light waves to trap and control particles.
光子阱:使用光波俘获并控制粒子。

Quantum dots are made of semiconductor material and are used to contain and manipulate electrons.
量子点:由半导体材料制成用来控制和操纵电子。

Semiconductor impurities contain electrons by using "unwanted" atoms found in semiconductor material.
半导体掺杂:通过使用半导体材料中“多余”的原子控制电子。

Superconducting circuits allow electrons to flow with almost no resistance at very low temperatures.
超导电路:让电子在超低温下几乎没有阻力地流动。

Today's Quantum Computers
今天的量子计算机

Quantum computers could one day replace silicon chips, just like the transistor once replaced the vacuum tube. But for now, the technology required to develop such a quantum computer is beyond our reach. Most research in quantum computing is still very theoretical.
量子计算机有一天将会取代硅芯片,就像晶体管曾经取代真空管。但至少目前,制造量子计算机所需的技术超出了我们的能力范围。在量子计算领域中的大部分研究仍是非常理论的。

The most advanced quantum computers have not gone beyond manipulating more than 16 qubits, meaning that they are a far cry from practical application. However, the potential remains that quantum computers one day could perform, quickly and easily, calculations that are incredibly time-consuming on conventional computers. Several key advancements have been made in quantum computing in the last few years. Let's look at a few of the quantum computers that have been developed.
目前最先进的量子计算机没有超过16个量子位,这意味着它们离实用还有很远的距离。然而量子计算机有潜力在某一天能够快速地和轻松地进行对传统计算机来说相当费时间的计算。这些年来在量子计算领域中已经取得了一些关键进展。让我们来看看几台曾经的量子计算机。

1998
Los Alamos and MIT researchers managed to spread a single qubit across three nuclear spins in each molecule of a liquid solution of alanine (an amino acid used to analyze quantum state decay) or trichloroethylene (a chlorinated hydrocarbon used for quantum error correction) molecules. Spreading out the qubit made it harder to corrupt, allowing researchers to use entanglement to study interactions between states as an indirect method for analyzing the quantum information.

Los Alamos 和MIT的研究人员。。。。。(这个太难了实在看不懂) 扩展量子位使得量子位更难衰退,允许研究人员利用纠缠态了解态之间的作用。这是间接分析量子信息的新方法。

2000
In March, scientists at Los Alamos National Laboratory announced the development of a 7-qubit quantum computer within a single drop of liquid. The quantum computer uses nuclear magnetic resonance (NMR) to manipulate particles in the atomic nuclei of molecules of trans-crotonic acid, a simple fluid consisting of molecules made up of six hydrogen and four carbon atoms. The NMR is used to apply electromagneticpulses, which force the particles to line up. These particles in positions parallel or counter to the magnetic field allow the quantum computer to mimic the information-encoding of bits in digital computers.

3月份,Los Alamos 国家实验室的科学家宣布了在一滴液体中的七个量子位的量子计算机的研究成果。这台量子计算机利用核磁共振操纵反式丁烯酸分子的原子核。反式丁烯酸是一种简单的由六个氢原子和四个碳原子组成的分子组成的液体。核磁共振被用来产生电磁脉冲,这促使粒子排成一列。这些处于与磁场方向平行或相反的位置上,允许量子计算机模拟数字计算机中的信息编码位。

Researchers at IBM-Almaden Research Center developed what they claimed was the most advanced quantum computer to date in August. The 5-qubit quantum computer was designed to allow the nuclei of five fluorine atoms to interact with each other as qubits, be programmed by radio frequency pulses and be detected by NMR instruments similar to those used in hospitals (see How Magnetic Resonance Imaging Works for details). Led by Dr. Isaac Chuang, the IBM team was able to solve in one step a mathematical problem that would take conventional computers repeated cycles. The problem, called order-finding, involves finding the period of a particular function, a typical aspect of many mathematical problems involved in cryptography.

八月份IBM-Almaden 研究中心的研究人员研制了他们声称是最先进的量子计算机。这台5个量子位的量子计算机通过五个氟原子核之间的作用作为量子位,使用无线电频率脉冲编程并且由类似于医院中的核磁共振仪探测。由Isaac Chuang领导的这个IBM团队解决了一个使传统计算机重复循环的数学问题的一步。这个叫“寻找顺序”的问题,包括寻找一个特殊函数的周期——一个包括密码学在内的许多数学问题中的一个典型方面。

2001
Scientists from IBM and Stanford University successfully demonstrated Shor's Algorithm on a quantum computer. Shor's Algorithm is a method for finding the prime factors of numbers (which plays an intrinsic role in cryptography). They used a 7-qubit computer to find the factors of 15. The computer correctly deduced that the prime factors were 3 and 5.
来自IBM和斯坦福大学的科学家成功地在量子计算机上演示了shor的算法。Shor的算法是一种寻找数字的质因子的方法(它在密码学中具有很高的地位)。他们使用一台7比特的量子计算机寻找15的因子。计算机正确地推到出因子是3和5.

2005
The Institute of Quantum Optics and Quantum Information at the University of Innsbruck announced that scientists had created the first qubyte, or series of 8 qubits, using ion traps.
Innsbruck大学的量子光学与量子信息学院宣布科学家通过使用光阱已经制造出了第一个量子字节,或是8个量子位。

2006

Scientists in Waterloo and Massachusetts devised methods for quantum control on a 12-qubit system. Quantum control becomes more complex as systems employ more qubits.

Waterloo and Massachusetts的科学家设计了一中控制12个量子位的系统的方法。当系统拥有更多的量子位时量子控制变得更复杂。
2007
Canadian startup company D-Wave demonstrated a 16-qubit quantum computer. The computer solved asudoku puzzle and other pattern matching problems. The company claims it will produce practical systems by 2008. Skeptics believe practical quantum computers are still decades away, that the system D-Wave has created isn't scaleable, and that many of the claims on D-Wave's Web site are simply impossible (or at least impossible to know for certain given our understanding of quantum mechanics).
加拿大的新兴公司D-Wave演示了一台16个量子位的量子计算机。这台计算机解决了一个数独问题和一些模式识别问题。该公司宣称会在2008年研制出实用的系统。怀疑论者认为距实用的量子计算机仍有十年的时间,D-Wave研制出的系统是不可提升的,并且D-Wave网站上的许多声明是不可能的(至少对于我们现在直到的量子力学来说是不可能的)。

If functional quantum computers can be built, they will be valuable in factoring large numbers, and therefore extremely useful for decoding and encoding secret information. If one were to be built today, no information on the Internet would be safe. Our current methods of encryption are simple compared to the complicated methods possible in quantum computers. Quantum computers could also be used to search large databases in a fraction of the time that it would take a conventional computer. Other applications could include using quantum computers to study quantum mechanics, or even to design other quantum computers.
如果实用的量子计算机能够被制造出来,它们在分解大数的领域将有巨大的价值,所以对于解码和编码秘密信息中发挥着巨大的作用。如果今天有一台被制造出来了,因特网上的任何信息都将会是不安全的。我们现今的加密方法在复杂的量子计算机面前都将变得简单。量子计算机也能够被用来搜索巨大的数据库,只需要很少的时间就能够胜任传统计算机。其他的应用包括利用量子计算机研究量子力学,或者是设计其他的量子计算机。

But quantum computing is still in its early stages of development, and many computer scientists believe the technology needed to create a practical quantum computer is years away. Quantum computers must have at least several dozen qubits to be able to solve real-world problems, and thus serve as a viable computing method.
For more information on quantum computers and related topics, check out the links on the next page.g
但是量子计算仍然处于发展的早期,许多计算机科学家相信制造距离量子计算机所需的技术还有数年的时间。量子计算机必须至少拥有数十个量子位才能够解决现实世界中的问题,并才能够成为可使用的计算方法。

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Posted 2014年1月16日 by zhangzimou in category translation