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A bathing cap that can watch individual neurons, allowing others to monitor the wearer’s mind. A sensor that can spot hidden nuclear submarines. A computer that can discover new drugs, revolutionise securities trading and design new materials. A global network of communication links whose security is underwritten by unbreakable physical laws. Such—and more—is the promise of quantum technology.
能够观察单个神经元，允许别人监测穿戴者所思所想的泳帽；可以侦测到潜藏核潜艇的传感器。能够发明新药，彻底改变证券交易和设计出新材料的计算机；以及安全性由牢不可破的物理定律提供保证的通信连接全球网络。这些都是量子技术带给我们的希望，未来还会有更多。
All this potential arises from improvements in scientists’ ability to trap, poke and prod single atoms and wispy particles of light called photons. Today’s computer chips get cheaper and faster as their features get smaller, but quantum mechanics says that at tiny enough scales, particles sail through solids, short-circuiting the chip’s innards. Quantum technologies come at the problem from the other direction. Rather than scale devices down, quantum technologies employ the unusual behaviours of single atoms and particles and scale them up. Like computerisation before it, this unlocks a world of possibilities, with applications in nearly every existing industry— and the potential to spark entirely new ones.
所有这些可能性来自于科学家捕捉，刺探和激发单个原子和一束光的粒子（又称光子）能力的提升。随着计算机芯片外形变得越来越小，它们的价格越来越便宜，运算速度越来越快。但量子力学表明，在足够小的尺度，粒子将穿过固体，短路芯片的内部结构。量子科技看待问题的角度来自另一个方向。它不是将器件尺寸缩小，而是利用单个原子和粒子的古怪行为，并将它们放大。就像之前的计算机化一样，这打开了一个充满各种可能性的世界。它的应用将遍及几乎每一个现有行业，并且有可能完全点亮新的可能性。
Strange but true
信不信由你
Quantum mechanics—a theory of the behaviour at the atomic level put together in the early 20th century—has a well-earned reputation for weirdness. That is because the world as humanity sees it is not, in fact, how the world works. Quantum mechanics replaced wholesale the centuries-old notion of a clockwork, deterministic universe with a reality that deals in probabilities rather than certainties—one where the very act of measurement affects what is measured. Along with that upheaval came a few truly mind-bending implications, such as the fact that particles are fundamentally neither here nor there but, until pinned down, both here and there at the same time: they are in a “superposition” of here-there-ness. The theory also suggested that particles can be spookily linked: do something to one and the change is felt instantaneously by the other, even across vast reaches of space. This “entanglement” confounded even the theory’s originators.
量子力学是20世纪早期发展起来的原子层面的行为理论，它有着应有的古怪名声。这是因为人类观察到的世界并非真实世界运作的方式。量子力学用可能性而不是确定性的新认知完全取代了几百年来钟表式精确，确定性宇宙的老观念。测量行为将影响被测量者，这种颠覆带来了一些令人费解的结果，例如，在被固定之前，同一时间粒子从本质上说既不在这儿也不在那儿，即在这里又在那里：他们处于这里-那里的“叠加”态。这个理论还表明，粒子可以是幽灵般连接在一起的：对一个施加作用，变化会即刻被另外一个感知，即便它们被分隔在广阔空间的两边。这种“纠缠”态甚至让量子理论的创造者也深感迷惑。
It is exactly these effects that show such promise now: the techniques that were refined in a bid to learn more about the quantum world are now being harnessed to put it to good use. Gizmos that exploit superposition and entanglement can vastly outperform existing ones—and accomplish things once thought to be impossible.
正是这些效应现在预示了这样的希望：为了更好得了解量子世界而不断完善的科技现在正被驾驭以期得到有效利用。利用叠加态和纠缠态的装置性能将远胜于现有的那些同类 - 而且将实现那些曾经认为可望而不可及的事情。
Improving atomic clocks by incorporating entanglement, for example, makes them more accurate than those used today in satellite positioning. That could improve navigational precision by orders of magnitude, which would make self-driving cars safer and more reliable. And because the strength of the local gravitational field affects the flow of time (according to general relativity, another immensely successful but counter intuitive theory), such clocks would also be able to measure tiny variations in gravity. That could be used to spot under ground pipes without having to dig up the road, or track submarines far below the waves.
例如，融合了纠缠态科技而改进过的原子钟，其卫星定位结果的精度超过了我们目前正在使用的原子钟。它将导航精度提高了几个数量级，这将使自动驾驶汽车更安全，更可靠。而且，根据广义相对论，另一个非常成功但反直觉的理论，局部重力场强度会影响时间的流动速度，这种装置也将能够测出重力的微小变化。其用途包括不必挖掘道路就能找到地下管道，或用于跟踪深藏大海中的潜艇。
Other aspects of quantum theory permit messaging without worries about eavesdroppers. Signals encoded using either superposed or entangled particles cannot be intercepted, duplicated and passed on. That has obvious appeal to companies and governments the world over. China has already launched a satellite that can receive and reroute such signals; a global, unhackable network could eventually follow.
量子理论的其他特性使得传送信息不必再担心被窃听。使用了叠加或纠缠粒子的编码信号将不能被拦截，复制和传递。这对全世界的公司和政府极具吸引力。中国已经发射了一颗可以接收和转发这种信号的卫星; 一个无法窃听的全球网络最终也将随之而来。
The advantageous interplay between odd quantum effects reaches its zenith in quantum computers. Rather than the 0s and 1s of standard computing, a quantum computer’s bits are in superpositions of both, and each “qubit” is entangled with every other. Using algorithms that recast problems in quantum-amenable forms, such computers will be able to chomp their way through calculations that would take today’s best super computers millennia. Even as high-security quantum networks are being developed, a countervailing worry is that quantum computers will eventually render obsolete today’s cryptographic techniques, which are based on hard mathematical problems.
奇量子效应之间这种有益的相互作用在量子计算机中将达到了顶点。量子计算机的比特不是标准计算中使用的0和1而是以两者的叠加态存在，每个“量子比特”还彼此纠缠着。使用用量子形式重构问题的算法，计算机能够完成那些当今最快的超级计算机需要一千年才能完成的运算量。在高安全性量子网络被开发的同时，让人产生抵触情绪的是担心量子计算机最终会使今天的加密技术过时。这种技术以难解的数学问题为开发基础。
Long before that happens, however, smaller quantum computers will make other contributions in industries from energy and logistics to drug design and finance. Even simple quantum computers should be able to tackle classes of problems that choke conventional machines, such as optimising trading strategies or plucking promising drug candidates from scientific literature. Google said last week that such machines are only five years from commercial exploitability. This week IBM, which already runs a publicly accessible, rudimentary quantum computer, announced expansion plans. As our Technology Quarterly in this issue explains, bigtech firms and startups alike are developing software to exploit these devices’ curious abilities. A new ecosystem of middlemen is emerging to match new hardware to industries that might benefit.
然而，在这些发生之前，较小型的量子计算机就会在各行各业做出不菲贡献，从能源到物流，从药物设计到金融。简单的量子计算机也能解决那些让传统计算机束手无策的问题，例如优化交易策略或从科学文献中挑选有前景的备选药物。上周谷歌宣布，这种计算机离商用只有五年时间。IBM已经在运行一个可以公开访问的原始量子计算机，本周他们宣布了扩张计划。正如我们的技术季报（Technology Quarterly）解释过的，大型科技公司和初创公司一样都在开发配套软件，以便利用这些计算机古怪的能力。新的中间生态系统正在出现，以便使新硬件和可能受益的行业相匹配。
The solace of quantum
量子的慰藉
This landscape has much in common with the state of the internet in the early 1990s: a largely laboratory-based affair that had occupied scientists for decades, but in which industry was starting to see broader potential. Blue-chip firms are buying into it, or developing their own research efforts. Startups are multiplying. Governments are investing “strategically”, having paid for the underlying research for many years—a reminder that there are some goods, such as blue-sky scientific work, that markets cannot be relied upon to provide.
这种情形与20世纪90年代早期互联网的情况有很多共同点：一个已经占用了科学家几十年时间，很大程度上是实验室为基地的那些事情，但行业里开始看到更广阔的潜力。蓝筹公司在买进，或者开展自己的研究努力；创业公司不断增加。政府也在做“战略性”投资，他们已经为基础研究投入了很多年。这提醒我们，有一些商品不能依靠市场来提供，比如纯理论的科学研究。
Fortunately for quantum technologists, the remaining challenges are mostly engineering ones, rather than scientific. And today’s quantum-enhanced gizmos are just the beginning. What is most exciting about quantum technology is its as yet untapped potential. Experts at the frontier of any transformative technology have a spotty record of foreseeing many of the uses it will find; Thomas Edison thought his phonograph’s strength would lie in elocution lessons. For much of the 20th century “quantum” has, in the popular consciousness, simply signified “weird”. In the 21st, it will come to mean “better”.
幸运的是，对量子科技专家们来说，剩下的挑战大多集中在工程学方面，而不是科学领域。今天的量子增强设备只是一个肇始。量子科技最令人激动之处在于它未被开发的潜能。任何变革性科技前沿的专家在预测新发现实际用途时的记录大多差强人意。托马斯爱迪生曾以为留声机发明的优势在于演讲学授课。20世纪的大部分时间，“量子”在普罗大众的意识里贴着一个“古怪”标签。在21世纪，它将意味着“更好”。