Quantum Cryptography Pioneers Win Turing Award
Gilles Brassard (left) and Charles Bennett were among the first to link quantum physics to information theory.
吉尔斯·布拉萨德（Gilles Brassard）（左）和查尔斯·贝内特（Charles Bennett）是最早将量子物理学与信息论联系起来的人之一。
Kristina Armitage/ Quanta Magazine
克里斯蒂娜·阿米蒂奇/广达杂志
One afternoon in October 1979, Gilles Brassard was swimming outside a beachfront hotel in San Juan, Puerto Rico, when a stranger swam up to him and changed the course of his career.
1979 年 10 月的一个下午，吉尔斯·布拉萨德 (Gilles Brassard) 在波多黎各圣胡安的一家海滨酒店外游泳时，一名陌生人游向他，改变了他的职业生涯。
Without so much as an introduction, the man began describing a way to create currency that couldn’t be forged.
没有做任何介绍，这个人就开始描述一种创造无法伪造的货币的方法。
The scheme was based on the laws of quantum physics — a subject Brassard, a computer scientist, knew nothing about.
该方案基于量子物理定律——计算机科学家布拉萨德对此一无所知。
“I was trapped, so I listened politely,” Brassard said.
“我被困住了，所以我礼貌地听着，”布拉萨德说。
Doubt soon turned to fascination as he realized that this exotic “quantum money” scheme was actually serious science.
当他意识到这种奇特的“量子货币”计划实际上是严肃的科学时，怀疑很快变成了迷恋。
That improbable meeting was the beginning of a long and fruitful collaboration between Brassard and his new acquaintance, a physicist named Charles Bennett .
这次不太可能的会面是布拉萨德和他的新朋友、一位名叫查尔斯·贝内特的物理学家之间长期而富有成果的合作的开始。
Their work would help launch the booming field of quantum information science, spurring the development of new technology and the discovery of fundamental connections between physics and information.
他们的工作将有助于启动蓬勃发展的量子信息科学领域，刺激新技术的发展以及物理与信息之间基本联系的发现。
Charles Bennett and Gilles Brassard have been named the winners of the A.M.
查尔斯·贝内特 (Charles Bennett) 和吉尔斯·布拉萨德 (Gilles Brassard) 被评为 A.M.
Turing Award, one of the highest honors in computing, for their work establishing the foundations of quantum information theory.
图灵奖是计算领域的最高荣誉之一，表彰他们为量子信息理论奠定了基础的工作。
Bennett and Brassard have now been named the winners of the A.M.
贝内特和布拉萨德现已被评为 A.M.
Turing Award , one of the highest honors in computing, for “their essential role in establishing the foundations of quantum information science and transforming secure communication and computing.” The award comes with a $1 million prize.
图灵奖是计算领域的最高荣誉之一，表彰其“在建立量子信息科学基础和变革安全通信和计算方面发挥的重要作用”。该奖项的奖金为 100 万美元。
Quantum information science is now home to thousands of active researchers, but until the mid-1990s it was a small community whose insights were often dismissed by outsiders.
量子信息科学现在拥有数千名活跃的研究人员，但直到 20 世纪 90 年代中期，它还是一个小团体，其见解经常被局外人忽视。
Bennett and Brassard were among its most vocal early advocates.
贝内特和布拉萨德是其最直言不讳的早期倡导者之一。
“They helped to set the culture for this group, which was kind of on the fringes of both physics and computer science at the time,” said John Preskill , a quantum physicist at the California Institute of Technology.
加州理工学院的量子物理学家约翰·普雷斯基尔 (John Preskill) 表示：“他们帮助建立了这个群体的文化，该群体当时处于物理学和计算机科学的边缘。”
Their influence on quantum information science was “massive,” said Scott Aaronson , a computer scientist at the University of Texas, Austin.
德克萨斯大学奥斯汀分校的计算机科学家斯科特·亚伦森 (Scott Aaronson) 表示，他们对量子信息科学的影响是“巨大的”。
“They were there since before quantum computing was even a field.”
“在量子计算成为一个领域之前，它们就已经存在了。”
It was no coincidence that Bennett and Brassard found themselves on the same Puerto Rican beach on that day nearly 50 years ago.
近 50 年前的那一天，贝内特和布拉萨德发现自己出现在波多黎各的同一个海滩上，这并非巧合。
Both were attending a conference on theoretical computer science , but the academic trajectories that had brought them there were strikingly different.
两人都参加了一个理论计算机科学会议，但他们的学术轨迹却截然不同。
Brassard had been born in Montreal in 1955.
布拉萨德 1955 年出生于蒙特利尔。
He learned advanced math from his older brother while still in elementary school and started college at age 13.
他在读小学时就向哥哥学习了高等数学，并于 13 岁时开始上大学。
In 1979, when he was just 24, he received his doctorate and joined the faculty of the University of Montreal.
1979年，年仅24岁的他获得博士学位，并加入蒙特利尔大学任教。
He went to the Puerto Rico conference to present results from his graduate research on the mathematical foundations of cryptography.
他参加了波多黎各会议，展示了他关于密码学数学基础的研究生研究成果。
A 1994 photo of the six researchers who invented quantum teleportation.
1994 年发明量子隐形传态的六位研究人员的照片。
Clockwise from top left: Richard Jozsa, William Wootters, Charles Bennett, Asher Peres, Claude Crépeau, Gilles Brassard.
从左上角顺时针方向：理查德·乔萨、威廉·伍特斯、查尔斯·贝内特、阿舍·佩雷斯、克劳德·克雷波、吉尔斯·布拉萨德。
Bennett’s journey was more circuitous.
贝内特的旅程更加曲折。
He was born in New York City in 1943, went to college intending to study biochemistry, and wound up doing graduate research at Harvard University at the intersection of chemistry and physics.
他 1943 年出生于纽约市，上大学时打算学习生物化学，最后在哈佛大学化学和物理交叉学科进行研究生研究。
All the while, he was growing increasingly interested in finding connections between physics and computation, at a time when the two subjects were considered largely unrelated.
与此同时，他对寻找物理和计算之间的联系越来越感兴趣，而当时这两个学科被认为基本上不相关。
While Bennett was working toward his doctorate in the late 1960s, his friend Stephen Wiesner would often visit what Bennett called his “communal hippie house” in Boston.
20 世纪 60 年代末，当贝内特攻读博士学位时，他的朋友史蒂芬·威斯纳 (Stephen Wiesner) 经常参观贝内特所说的他在波士顿的“嬉皮士公共住宅”。
On one such visit, Wiesner brought a draft of a paper he’d written about a radically new application of quantum physics: the quantum money scheme with which Bennett would ambush Brassard a decade later.
在一次这样的访问中，威斯纳带来了他写的一篇论文草稿，内容涉及量子物理学的全新应用：十年后贝内特将用量子货币计划伏击布拉萨德。
Wiesner’s idea was motivated by one of the most important requirements for any form of currency: It should be very difficult to create a convincing counterfeit banknote.
威斯纳的想法源于对任何形式的货币最重要的要求之一：制造一张令人信服的假钞应该非常困难。
It’s not enough to give each bill a unique serial number if anyone can in principle read that number and copy it, so governments resort to sophisticated technology to thwart forgery.
如果原则上任何人都可以读取并复制每个钞票的序列号，那么为每张钞票赋予唯一的序列号是不够的，因此政府采用先进的技术来阻止伪造。
Wiesner realized that the laws of quantum physics could offer a new solution to the problem of counterfeiters.
威斯纳意识到量子物理定律可以为造假者问题提供新的解决方案。
His scheme exploited a strange feature of quantum measurement: Attempting to measure a particle can disturb it in an inherently unpredictable way, erasing all information about the state it was in before the measurement.
他的方案利用了量子测量的一个奇怪特征：试图测量一个粒子可能会以一种本质上不可预测的方式干扰它，从而抹掉有关测量前粒子状态的所有信息。
You can avoid this disturbance with a judicious choice of measurement, but only if you already have some partial information about the particle’s initial state.
您可以通过明智地选择测量来避免这种干扰，但前提是您已经掌握了有关粒子初始状态的部分信息。
Each of Wiesner’s hypothetical quantum banknotes would contain a group of particles in different quantum states.
威斯纳假设的每张量子钞票都将包含一组处于不同量子态的粒子。
These particles would encode the bits of a unique serial number.
这些粒子将对唯一序列号的位进行编码。
A would-be counterfeiter would need to measure every particle in the group without disturbing it to learn that serial number and create a duplicate.
潜在的造假者需要在不干扰该组粒子的情况下测量该组中的每个粒子，以了解该序列号并创建一个副本。
With just a few dozen particles, failure would be all but guaranteed.
只要有几十个粒子，失败几乎是注定的。
Quantum measurement disturbance, ordinarily a nuisance, would serve as a shield against prying eyes.
量子测量干扰通常是一件令人讨厌的事情，但它可以充当防止窥探的盾牌。
Stephen Wiesner, who devised the first quantum money scheme, in 1970.
斯蒂芬·威斯纳（Stephen Wiesner）于 1970 年设计了第一个量子货币方案。
In the early 1970s, Wiesner abruptly abandoned physics research and joined the California counterculture, and his revolutionary paper remained unpublished for nearly 15 years.
20世纪70年代初，威斯纳突然放弃了物理学研究，加入了加州反主流文化，他的革命性论文在近15年里都没有发表。
(Wiesner later embraced religion, moved to Israel, and became a construction worker.
（威斯纳后来信奉宗教，移居以色列，并成为一名建筑工人。
He died in 2021 .) Bennett, meanwhile, eventually landed a job at IBM, where he developed a new theory of reversible computation .
他于 2021 年去世。）与此同时，贝内特最终在 IBM 找到了一份工作，在那里他开发了一种新的可逆计算理论。
But he couldn’t get Wiesner’s idea out of his mind.
但他无法将威斯纳的想法从脑海中抹去。
He tried to interest other researchers for a decade, to no avail, until he met Brassard in Puerto Rico.
十年来，他试图引起其他研究人员的兴趣，但没有成功，直到他在波多黎各遇见了布拉萨德。
As they bobbed in the waves on that fateful day, Brassard pointed out a glaring problem with the quantum money scheme.
在那决定性的一天，当他们在海浪中漂浮时，布拉萨德指出了量子货币计划的一个明显问题。
It would be impossible to counterfeit banknotes, but it would also be difficult to use them, since only the person who created a bill would be able to check that it was valid.
伪造钞票是不可能的，但使用它们也很困难，因为只有制作钞票的人才能检查它是否有效。
Brassard suggested that it might be possible to patch this problem by combining Wiesner’s scheme with techniques from cryptography.
布拉萨德建议，通过将威斯纳的方案与密码学技术相结合，也许可以解决这个问题。
By the time the duo returned to shore 10 minutes later, they had settled on the key ideas in what would later become their first joint paper .
十分钟后，当两人返回岸上时，他们已经确定了后来成为他们第一篇联合论文的关键思想。
After that initial encounter, Bennett and Brassard would visit each other occasionally to swap ideas.
初次见面后，贝内特和布拉萨德偶尔会互相拜访，交换想法。
They could only afford to devote so much time to their shared interest in the obscure subject of quantum information.
他们只能投入这么多的时间来研究量子信息这个晦涩难懂的主题的共同兴趣。
“In those days, it was nobody’s day job,” Bennett said.
“在那些日子里，这不是任何人的日常工作，”贝内特说。
The duo began to wonder whether they could harness quantum measurement disturbance to keep secret messages safe from eavesdroppers.
两人开始思考是否可以利用量子测量干扰来保护秘密信息免遭窃听。
Cryptographers already knew one encryption scheme that was perfectly secure in principle.
密码学家已经知道一种原则上完全安全的加密方案。
But it required the sender and receiver, typically called Alice and Bob, to meet in person and choose a long string of random bits to use as a secret encryption key.
但它要求发送者和接收者（通常称为 Alice 和 Bob）亲自会面，并选择一长串随机位用作秘密加密密钥。
What’s more, they’d need to use a separate key for each new message.
此外，他们需要为每条新消息使用单独的密钥。
These restrictions were too cumbersome for most applications.
这些限制对于大多数应用程序来说太麻烦了。
More practical encryption schemes avoided the need for in-person meetings but relied on unproven assumptions about the difficulty of certain math problems.
更实用的加密方案避免了面对面会议的需要，但依赖于对某些数学问题的难度未经证实的假设。
In 1983, Bennett and Brassard devised a new quantum approach to private communication.
1983 年，Bennett 和 Brassard 设计了一种新的私人通信量子方法。
In their scheme, now known as BB84, Alice and Bob would establish a shared secret key by sending and measuring photons, the quantum particles that constitute light, without ever needing to meet in person.
在他们现在被称为 BB84 的方案中，爱丽丝和鲍勃将通过发送和测量光子（构成光的量子粒子）来建立共享密钥，而无需亲自见面。
They could then use that key to encrypt a message.
然后他们可以使用该密钥来加密消息。
The method again made use of quantum measurement disturbance: Any eavesdropper who tried to snoop on the quantum transmissions would disrupt them, learning nothing and alerting Alice and Bob to their presence.
该方法再次利用了量子测量干扰：任何试图窥探量子传输的窃听者都会扰乱它们，不会学到任何东西，并提醒爱丽丝和鲍勃他们的存在。
It also didn’t rely on any mathematical assumptions.
它也不依赖于任何数学假设。
Not even an eavesdropper who could magically solve the world’s hardest math problems would learn the secret key.
即使是能够神奇地解决世界上最难的数学问题的窃听者也不会知道密钥。
Bennett and Brassard’s quantum key distribution paper would become one of the most famous works in quantum information science.
贝内特和布拉萨德的量子密钥分发论文将成为量子信息科学领域最著名的著作之一。
But at the time, few took notice.
但当时，很少有人注意到。
So the duo eventually decided to build an experimental demonstration.
因此，两人最终决定建立一个实验演示。
“I wanted to show that it’s possible, that it’s not just nonsense from a theoretician,” Brassard said.
“我想证明这是可能的，这不仅仅是理论家的胡言乱语，”布拉萨德说。
They were there since before quantum computing was even a field.
在量子计算成为一个领域之前，它们就已经存在了。
With no budget and little experience in experimental physics, Bennett and Brassard’s team had to improvise.
由于没有预算，也缺乏实验物理经验，贝内特和布拉萨德的团队不得不即兴发挥。
At one point Bennett and his colleague John Smolin bought a sheet of black velvet from a fabric store to block out stray light, telling the confused shop clerk that they needed it for quantum cryptography.
有一次，贝内特和他的同事约翰·斯莫林从一家布料店买了一张黑色天鹅绒来阻挡杂散光，并告诉困惑的店员他们需要它来进行量子密码学。
(Bennett later repurposed the velvet for a hat.) They finally got the experiment working in October 1989 — 10 years to the day after Bennett and Brassard’s first meeting in Puerto Rico.
（贝内特后来将天鹅绒改造成一顶帽子。）1989 年 10 月，他们终于让实验成功了——距离贝内特和布拉萨德在波多黎各第一次会面已经过去 10 年了。
Their apparatus demonstrated quantum key distribution across a distance of 30 centimeters.
他们的设备展示了 30 厘米距离内的量子密钥分发。
More recent demonstrations using satellite links have implemented their method over more than 1,000 kilometers .
最近使用卫星链路的演示已经在超过 1,000 公里的范围内实施了他们的方法。
In 1993, Bennett, Brassard, and four other researchers published another iconic paper that showed how to use a bizarre quantum phenomenon called entanglement to “teleport” the state of one quantum particle onto another.
1993 年，贝内特、布拉萨德和其他四位研究人员发表了另一篇标志性论文，展示了如何利用一种称为纠缠的奇异量子现象将一个量子粒子的状态“传送”到另一个量子粒子上。
(Though the name calls to mind Captain Kirk getting beamed up to the Enterprise, quantum teleportation transmits only information, not matter.) It was one of the first examples of how entanglement could serve as a resource for information processing.
（虽然这个名字让人想起柯克船长被传送到企业号，但量子隐形传态只传输信息，而不是物质。）这是纠缠如何作为信息处理资源的第一个例子。
By that point, quantum information science was attracting a bit of buzz.
那时，量子信息科学引起了一些关注。
It really took off a year later.
一年后它真的起飞了。
Digital encryption often relies on the assumption that it’s hard for a computer to break a large number into its prime factors.
数字加密通常依赖于这样的假设：计算机很难将大量数字分解为其质因数。
But in 1994, the applied mathematician Peter Shor devised a quantum algorithm that could quickly do just that.
但在 1994 年，应用数学家 Peter Shor 设计了一种量子算法，可以快速做到这一点。
Shor’s milestone result underscored the importance of quantum encryption methods that didn’t require assumptions about mathematical difficulty.
肖尔的里程碑式结果强调了不需要对数学难度进行假设的量子加密方法的重要性。
“Shor’s algorithm made our idea unavoidable,” Brassard said.
“肖尔的算法让我们的想法不可避免，”布拉萨德说。
In the 30 years since Shor’s discovery, interest and investment in quantum information science have skyrocketed.
自 Shor 发现以来的 30 年来，人们对量子信息科学的兴趣和投资猛增。
Researchers have raced to build powerful quantum computers and identified connections to seemingly unrelated topics in fundamental physics .
研究人员竞相建造强大的量子计算机，并确定了与基础物理学中看似无关的主题的联系。
There’s also been a surge of new interest in quantum cryptography.
人们对量子密码学的新兴趣也激增。
Until a few years ago, researchers believed that quantum tricks were only useful for a few special cryptographic tasks like key distribution.
直到几年前，研究人员还认为量子技巧仅对一些特殊的加密任务有用，例如密钥分发。
But a recent line of work has offered tantalizing hints that the scope of quantum cryptography might be much broader.
但最近的一系列工作提供了诱人的暗示，表明量子密码学的范围可能要广泛得多。
Bennett and Brassard have followed these new developments with interest.
贝内特和布拉萨德饶有兴趣地关注着这些新的发展。
“That is a very fascinating idea,” Bennett said.
“这是一个非常令人着迷的想法，”贝内特说。
“It might be a way where there’s a quantum rescue from the quantum disaster of Shor’s algorithm.”
“这可能是从肖尔算法的量子灾难中进行量子拯救的一种方式。”
Editor’s note: Scott Aaronson is a member of Quanta Magazine ’s advisory board.
编者注：斯科特·阿伦森 (Scott Aaronson) 是《Quanta》杂志顾问委员会的成员。
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《Quanta》杂志对评论进行审核，以促进知情、实质性、文明的对话。
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辱骂、亵渎、自我推销、误导、语无伦次或偏离主题的评论将被拒绝。
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