PsiQuantum has a plan to make a massive quantum computer out of light

PsiQuantum 计划利用光打造一台大型量子计算机

The machine that could change the world will be housed in a room that looks like a data center crossed with an ice cream factory. Inside will be some 100 stainless-steel cabinets, each about six feet tall and connected to a supply of liquid helium that keeps them only a few degrees above absolute zero. Inside those cabinets will be hundreds of chips, and on those, thousands of particles of light flying through a maze of optical switches and beam splitters. Each photon must be accounted for, because precisely measuring where it ends up will help answer questions that current computers might take millions of years to solve. 这台可能改变世界的机器将被安置在一个看起来像是数据中心与冰淇淋工厂结合体的房间里。房间内将放置约 100 个不锈钢机柜，每个机柜高约六英尺，并连接着液氦供应系统，使其保持在仅比绝对零度高出几度的温度。这些机柜内部将装有数百块芯片，芯片上有数千个光粒子穿梭于由光学开关和分束器组成的迷宫中。每一个光子都必须被精确追踪，因为精确测量它们的最终位置将有助于解答那些当前计算机可能需要数百万年才能解决的问题。

This computer, as described, does not exist. It’s the brainchild of a company called PsiQuantum, founded in 2016 by four physicists from UK universities. In a crowded field of deep-pocketed competitors with similarly fantastical visions, the company aims to be first to fulfill its promise. 正如所描述的那样，这台计算机目前还不存在。它是 PsiQuantum 公司的结晶，该公司由四位来自英国大学的物理学家于 2016 年创立。在竞争激烈、资金雄厚且拥有同样宏大愿景的同行中，该公司旨在成为第一个兑现承诺的企业。

In the years since the physicist Richard Feynman first envisioned them in 1981, quantum computers have promised to speed up everything from medical research to AI by harnessing the qualities of quantum particles. Unlike normal computer bits, which can be either a 1 or 0, quantum bits can exist in multiple states at once. And combining enough of those quantum bits together could produce a computer capable of tasks well beyond the reach of today’s conventional machines. 自物理学家理查德·费曼（Richard Feynman）于 1981 年首次提出量子计算机的概念以来，量子计算机一直承诺通过利用量子粒子的特性，加速从医学研究到人工智能等各个领域的发展。与普通计算机比特（只能是 0 或 1）不同，量子比特可以同时存在于多种状态。将足够多的量子比特结合在一起，就能制造出一台能够完成远超当今传统机器任务的计算机。

But even today’s best quantum prototypes are too small and error-prone to do anything useful. That makes PsiQuantum’s promises for what its computers will ultimately do all the more bold. Consider the company’s hopes for predicting the effects of cytochrome P450 enzymes, which often break down drugs in the body. If pharma companies knew more precisely how they would work on a particular molecule, they could design more effective medications faster. Estimating this for a specific drug can take over 10 years with today’s methods, says Philipp Ernst, vice president of quantum applications for PsiQuantum, but “we aim to get it down to four minutes.” 然而，即使是当今最先进的量子原型机也太小且容易出错，无法执行任何实际用途。这使得 PsiQuantum 对其计算机最终功能的承诺显得更加大胆。以该公司希望预测细胞色素 P450 酶（通常在体内分解药物）的影响为例。如果制药公司能更精确地了解这些酶如何作用于特定分子，他们就能更快地设计出更有效的药物。PsiQuantum 量子应用副总裁 Philipp Ernst 表示，使用当今的方法评估某种特定药物可能需要超过 10 年的时间，但“我们的目标是将其缩短到四分钟。”

The company’s chips will be contained in large cabinets. A quantum computer powerful enough to be commercially useful is expected to require roughly 100 of these cabinets connected together. 该公司的芯片将被装在大型机柜中。一台功能强大到足以实现商业用途的量子计算机预计需要将大约 100 个这样的机柜连接在一起。

In a field full of such claims, PsiQuantum has attracted unusual investment and scrutiny for two reasons: It is one of the few companies aiming directly at building a large and useful machine, and it is already working with a major chip manufacturer to build its systems using existing semiconductor fabs. Its vision has attracted momentum: Last year, PsiQuantum raised $1 billion in funding and broke ground in Chicago on a site it’s building in partnership with local governments. It also has a second site in the works in Australia, which it promises will be operational—meaning hardware-ready—in 2027. And it’s one of just two companies (along with Microsoft) to reach the third stage of an intensive government evaluation program to see which quantum companies might succeed. 在充满此类声明的领域中，PsiQuantum 因两个原因吸引了不同寻常的投资和关注：它是少数几家直接致力于建造大型且实用机器的公司之一，并且它已经与一家大型芯片制造商合作，利用现有的半导体晶圆厂来构建其系统。其愿景已形成势头：去年，PsiQuantum 筹集了 10 亿美元资金，并在芝加哥破土动工，与当地政府合作建设一个基地。它在澳大利亚还有第二个正在筹备中的基地，并承诺将于 2027 年投入运营（即硬件就绪）。此外，它是仅有的两家（另一家是微软）进入政府密集评估计划第三阶段的公司之一，该计划旨在评估哪些量子计算公司可能取得成功。

Evaluating whether PsiQuantum will do what it says is harder than, say, judging a drugmaker by its clinical trial results: Advances in quantum computing are incremental, opaque, and tough to verify from the outside. But the company is now approaching its prove-it moment, when years of closed-door work and hundreds of millions in investment will either culminate in a useful quantum computer or fall short. We could start to know which as soon as next year. 评估 PsiQuantum 是否能兑现承诺，比通过临床试验结果来评判一家制药商要困难得多：量子计算的进步是渐进的、不透明的，且从外部很难验证。但该公司现在正接近其“证明时刻”，多年闭门造车和数亿美元的投资最终要么会成就一台实用的量子计算机，要么会以失败告终。我们最早可能在明年就能知道结果。

A new kind of machine

一种新型机器

Terry Rudolph, one of PsiQuantum’s four founders, is soft-spoken and shaggy-haired. He was born in Malawi and learned only after earning his first physics degree that he is a grandson of the famed physicist Erwin Schrödinger. He later self-published a 150-page book to explain quantum computing to teenagers (my PR contact gave me a signed copy with a wink that said “We never expect anyone to actually read this,” but I can report that it is a funny and helpful book). PsiQuantum 的四位创始人之一特里·鲁道夫（Terry Rudolph）说话轻声细语，留着一头乱发。他出生于马拉维，直到获得第一个物理学学位后才知道自己是著名物理学家埃尔温·薛定谔（Erwin Schrödinger）的孙子。后来，他自费出版了一本 150 页的书，向青少年解释量子计算（我的公关联系人给了我一本签名版，并眨着眼说：“我们从没指望有人真的会读它”，但我可以负责任地说，这是一本既有趣又有用的书）。

Around 2014, Rudolph and his cofounders became increasingly convinced that the quantum breakthroughs they were finding to be possible in theory might also be possible in a real machine. They eventually left their academic positions and divided the tasks before them: Rudolph worked on theory, Mark Thompson on engineering, Pete Shadbolt on scaling the technology up, and Jeremy O’Brien on articulating the vision and finding investors (O’Brien served as CEO until February; he’s been replaced by Victor Peng, a veteran of the semiconductor industry). 大约在 2014 年，鲁道夫和他的联合创始人们越来越确信，他们在理论上发现的量子突破也可能在真实的机器中实现。他们最终离开了学术职位，并分工合作：鲁道夫负责理论，马克·汤普森（Mark Thompson）负责工程，皮特·沙德博尔特（Pete Shadbolt）负责技术扩展，杰里米·奥布莱恩（Jeremy O’Brien）负责阐述愿景和寻找投资者（奥布莱恩担任首席执行官至今年 2 月；他已被半导体行业资深人士 Victor Peng 取代）。

To understand why the quantum computer the company is building would be a big deal, consider how imprecise much of modern science remains. We cannot reliably predict, for example, which lithium-ion battery will catch fire or how quickly a critical aircraft component will corrode. This isn’t just because these systems are complex, though they are. It’s that, at their core, they are governed by quantum mechanics. Subatomic particles don’t have well-defined properties—this location and that velocity—but instead occupy quantum states spread across many possibilities. And that in turn influences a range of atomic and molecular behavior. 要理解为什么该公司正在建造的量子计算机意义重大，可以看看现代科学在许多方面仍然是多么不精确。例如，我们无法可靠地预测哪块锂离子电池会起火，或者关键的飞机部件腐蚀速度有多快。这不仅仅是因为这些系统很复杂（尽管它们确实很复杂），而是因为它们的核心受量子力学支配。亚原子粒子没有明确定义的属性（如特定的位置和速度），而是占据分布在多种可能性中的量子态。这反过来又影响了一系列原子和分子的行为。

Schrödinger (Rudolph’s grandfather, remember) showed how to describe this haziness mathematically a century ago this year, but precisely carrying out the calculations on real-world systems quickly becomes unfeasible even for the best computers. Scientists cope with this gap using approximations, imperfect simulations, or experiments on animals. 薛定谔（记住，这是鲁道夫的祖父）在一百年前就展示了如何用数学方法描述这种模糊性，但在现实系统上精确执行这些计算，即使对于最好的计算机来说也很快变得不可行。科学家们通过使用近似值、不完美的模拟或动物实验来应对这一差距。

Feynman, David Deutsch, and other physicists in the 1980s wondered if we could do better. Maybe such complexity could instead be modeled using a new kind of machine. Rather than using transistors that are only… 费曼、大卫·多伊奇（David Deutsch）和其他物理学家在 20 世纪 80 年代想知道我们是否能做得更好。也许这种复杂性可以用一种新型机器来建模。与其使用那些只能……