回应IBM质疑 谷歌正式宣布“量子霸权”实现 但事实果真如此吗？

北京时间10月23日晚，《自然》（Nature）杂志在官网上官宣：一个月前被NASA发表随即又撤下的谷歌“量子霸权”论文重新发表，这项研究标志着“量子领域”中的重要里程碑。

Alphabet Inc."s Google said on Wednesday it had achieved a breakthrough in computing research by using a quantum computer to solve in minutes a complex problem that would take today"s most powerful supercomputer thousands of years to crack.

Google researchers expect that quantum computers within a few years will fuel advancements in fields such as artificial intelligence, materials science, and chemistry. The company isracing rivals including IBM Corp. and Microsoft Corp. to be the first to commercialize the technology and sell it through its cloud computing business."We"re hoping that when people start using this and looking at performance stability and cloud interface, they"ll get really excited about what we have to offer at Google," John Martinis, the company"s chief scientist for quantum hardware, told reporters.The breakthrough was described in a paper published in science journal Nature. It followed weeks of controversy since a draft leaked over whether Google"s claim of "quantum supremacy" was valid.

IBM said a supercomputer employing a different set-up could solve the same challenge in under three days, while chipmaker Intel said "quantum practicality" remained years away.

量子霸权是啥

谷歌在论文中表示，称其已经开发出了一款54量子比特数的量子芯片，名为Sycamore，由铝、铟、硅晶片和超导体等材料组成，每个量子比特和临近的4个量子比特耦合。不过，实际上执行运算的只有 53 个量子比特和 86 个耦合器，剩下的 1 个量子比特无法正常工作。

通过一系列实验和计算，谷歌研究人员开发了一套高保真度的纠错流程，Sycamore芯片支持的量子计算机只需要200秒，同时维持很低的误差率，而目前世界超算Summit需要1万年。Google defended its position, but did not dispute rivals" contentions. It has manufactured a handful of chips with 54 "qubits," vastly more powerful than the standard 64-bit chip in many consumer devices. However, for the technology to be useful to customers it would need to make chips with thousands of qubits.

Martinis said Google sees "a pathway" to a computer with 1,000 qubits and expressed confidence that it had a reliable process to make its new chip, dubbed Sycamore.

The U.S. and Chinese governments have led in the burgeoning quantum technology field, pledging billions of dollars in funding to corporate and state researchers to fast-track quantum development and mitigate possible issues, including the tech"s expected ability to break digital encryption.

Google has been among the beneficiaries of the American support. "The United States has taken a great leap forward in quantum computing," said U.S. chief technology officer Michael Kratsios on Wednesday.

Sundar Pichai and Daniel Sank (R) with one of Google"s Quantum Computers in the Santa Barbara lab, California, U.S. /Reuters Photo

业界的质疑声

以 IBM 为首的质疑派认为，虽然这是一个里程碑，但谷歌的实验有缺陷，执行同样的计算实验，经典计算机可能也只需要2.5天，远远没有谷歌所说的1万年那么夸张。除此之外，谷歌离真正的量子计算机还有很长的路要走，因为它执行的计算任务没有已知用途，不足以证明其通用性，而且如何实现可持续的容错运算依然是个巨大挑战（谷歌在论文中也承认了这一点）。换句话说，谷歌“老王卖瓜”式——“实现量子霸权”的言论是具有误导性的。For decades, computer scientists have sought to harness quantum physics, laws governing the behavior of particles that are smaller than atoms and can simultaneously exist in different states.

Quantum bits, or qubits, can be set to one and zero at the same time, unlike today"s computer bits that are either ones or zeros. This superposition property multiplies exponentially as qubits become entangled with each other, meaning the more qubits connected, the vastly more powerful a quantum computer becomes.

But there is a catch: Quantum researchers need to cool qubits to about absolute zero (-273 degrees Celsius or -460 degrees Fahrenheit) to limit vibration – or "noise" – that causes errors in calculations. It is in this challenging task that Google, which has designed much of its own electronics and used liquid helium for cooling, has made significant progress.

A component of Google"s Quantum Computer in the Santa Barbara lab, California, U.S. /Reuters Photo

谷歌研究团队在媒体发布会上呼吁大家把目光放长远，而非纠结于“量子霸权”实现与否。CEO Sundar Pichai compared the achievement to building the first rocket to leave Earth"s atmosphere and touch the edge of space, an advance that brought interplanetary travel into the realm of the possible.

"For those of us working in science and technology, it"s the "hello world" moment we"ve been waiting for – the most meaningful milestone to date in the quest to make quantum computing a reality," Pichai wrote in a blog here.

Sycamore, measuring about 10 mm (0.39 inch) across, is made using aluminum and indium parts sandwiched between two silicon wafers. In their experiment this year, the researchers were able to get 53 of Sycamore"s qubits to interact in a quantum state.

They then had the quantum computer detect patterns in a series of seemingly random numbers, and it succeeded in three minutes and 20 seconds. They estimated that the same problem would take 10,000 years for a Summit supercomputer – the most powerful in the world today – to solve.

CEO Sundar Pichai with one of Google"s Quantum Computers in the Santa Barbara lab, California, U.S. /Reuters Photo

据称，谷歌已经在此项目上持续投入了的精力，但驱使谷歌费时费力投资这个项目的动力是什么呢？《麻省理工科技评论》对谷歌CEO Sundar Pichai 的独家专访中揭露了答案。

Sundar Pichai 强调此次的研究成果对谷歌来说具有“里程碑”式的意义，他表示，”我们需要一台能容下更多量子比特且容错的量子计算机，以便运算更复杂且通用的算法。就好比拿飞机来说，莱特兄弟当时发明的第一架飞机仅在空中飞行了约12秒钟，其设计在生活中并没有任何实际应用，但它确实证明了飞机的概念是可行的，在这一点上量子计算也不例外。“

不过，科学上的突破都是令人期待的，能否造福于人类需经历时间的沉淀。While the peer-reviewed research has drawn plaudits, with MIT"s William D. Oliver comparing it to the Wright brothers" first flights, skeptics say Google is over-selling its achievement.

IBM said a supercomputer with additional disk storage can solve the random number problem in at most 2-1/2 days and with greater accuracy. It also said Google risked misleading the public by implying the new-style computers would replace existing ones.

"Quantum computers will never reign "supreme" over classical computers, but will rather work in concert with them, since each have their unique strengths," Dario Gil, director of research at IBM, wrote in a blog here.

Torsten Siebert, manager of the quantum computing research program at Germany"s Fraunhofer Society, agreed that "progress was likely to be achieved through such hybrid combinations."

Researchers also have expressed concern about quantum computers being used, for example, to unseal secure >

But before quantum computers can break codes, security experts have plenty of time to adapt, Martinis said.

"We"re pretty confident we"ll all stay safe and secure in the future," he said.