How quantum computing can help tackle global warming

Quantum computing has the potential to drive the major breakthroughs needed to help solve the climate crisis. A pioneer in the field discusses how his company is seeking to harness this technology for large-scale climate-change mitigation.

Once they are ready for commercial deployment, quantum computers are expected to bring about massive disruption and create enormous value across a broad range of industries. Quantum computing’s unique ability to simulate the chemistry underpinning all human activity means it could help achieve breakthrough innovations in carbon capture, new fuels, batteries, fertilizers, catalysts, and more. Jeremy O’Brien, CEO and cofounder of PsiQuantum, speaks with McKinsey’s Philipp Hillenbrand about his company’s approach to accelerating and scaling the technology and its bold vision to deploy it in the fight against climate change.

Key insight #1: Rapidly accelerating the development timeline for a commercially viable quantum computer requires a fundamentally different approach.

Philipp Hillenbrand: Could you elaborate on the different technologies underlying quantum computing and why PsiQuantum has placed its bets on a photonics-based system from the beginning?

Jeremy O’Brien: The first thing you need to understand is that all known useful applications of a quantum computer require error correction, and therefore something on the order of a million quantum bits, or qubits. Breakthroughs to date involve systems with up to around 100 qubits, so there’s a big gap. From the start, PsiQuantum has been exclusively focused on building a quantum computer capable of addressing commercially useful applications. My conviction for more than 20 years has been that for such a machine to become a reality in my lifetime, we would need to leverage the same advanced semiconductor manufacturing techniques that put a billion transistors in your cell phone.

The challenge is that semiconductor foundries are very constrained in the materials and devices that they can build. Qubits often require millikelvin temperatures, atomic-scale fabrication, or exotic materials that are not compatible with semiconductor manufacturing.

Our team has created an architecture based on photonic qubits, which avoids these more difficult requirements and allows us to use silicon photonics—a technology that has been developed over the past 25 years, principally by the telecom industry but increasingly for other applications. We can generate, manipulate, and measure qubits using standard components that already exist in commercial products. This approach massively accelerates our timeline to a million qubits.

Beyond the potential to manufacture large numbers of qubits, photons have significant advantages when it comes to scaling. Current quantum computing systems are hamstrung by four major challenges: cooling power, control electronics, connectivity, and testing. Our photonic architecture uniquely addresses all of these challenges and supports our ability to rapidly iterate toward a working machine.

These advantages are the basis for my long-held belief that photonics is really the only approach that can reach the necessary scale for fault-tolerant quantum computing on any practical level of time or money.

Key insight #2: Quantum computing applications, once thought to be decades away, could now happen within the next ten years.

Philipp Hillenbrand: What would you say to a skeptic who believes quantum computing will forever remain in the realm of science fiction and not become something of practical value?

Jeremy O’Brien: I would say that you’re right to be skeptical, given the immense challenge. If we hadn’t cracked the problem of using the production lines of a world-leading semiconductor foundry to manufacture the chips, I would still be telling everyone today that quantum computing is decades away. But whereas we used to build this stuff in a research lab, we are now building it in the production lines of the semiconductor foundry, shoulder to shoulder with the chips that are in your laptop and cell phone. It is rapidly becoming a mature technology. We have simulated the architecture in fine detail, and there are no fundamental technical obstacles. We have demonstrated all of the building blocks, such as entangling gates, small-scale algorithms, and so on.

In 1995, I first learned that quantum computing might bring about a revolution akin to the agricultural, industrial, and digital revolutions. Back then, it seemed far-fetched that quantum mechanics could be harnessed to such momentous effect. But today, PsiQuantum is seeing great interest coupled with a high level of sophistication from Fortune 500 companies that are working with us to understand how they will deploy quantum computing to drive major advancements across a wide range of applications and use cases. They are doing this now to ensure that they have access to this profoundly world-changing technology when it comes online, thereby enabling a first-mover advantage in what promises to be a winner-takes-all type of dynamic.

All this gives me tremendous confidence that we will be able to achieve useful applications within this decade.