The path to a million qubits

All the computers in the world combined wouldn't match the capabilities of a one-million-qubit quantum computer. Which is why there's a race to solve it.

A Quick Recap on Qubits

To understand quantum computing, imagine a light switch. In a traditional computer, a bit (the basic unit of information) is either ON (1) or OFF (0). These bits are the foundation of classical computing.

Now, imagine a magical light switch that can be ON and OFF at the same time — that’s what a qubit can do. Thanks to a phenomenon called superposition, a qubit can exist as both a 1 and a 0 simultaneously.

Why Does This Matter?

Think of a maze. A regular computer would try each path one by one, like someone walking through the maze. But a quantum computer, using qubits, can explore all possible paths at the same time. This ability allows quantum computers to solve certain problems exponentially faster than classical computers.

What Are Qubits Made Of?

Quantum computers use different approaches to create qubits. Here are some of the leading technologies:

• Superconducting Circuits: These are tiny loops of superconducting material that carry electrical current without resistance. Companies like IBM, Google, and Rigetti focus on this method.

• Trapped Ions: These qubits are formed by charged atoms (ions) held in place using electromagnetic fields and manipulated with lasers. Companies like Quantinuum (formerly Honeywell) and IonQ specialize in this approach.

• Photons: These qubits are based on individual particles of light, which are manipulated for quantum computation. PsiQuantum is a leader in this field.

• Topological Qubits: Instead of storing quantum information in a single particle (like an atom or electron), topological qubits encode it in collective quantum states spread across a system. This unique approach makes topological qubits more resistant to errors, offering better stability and scalability. Microsoft has been pioneering this method.

Where Are We Now?

Today, quantum computers have tens to a few hundred qubits, depending on the company and technology used. For example:

• IBM’s Quantum Hummingbird has around 65 qubits.

• Google’s Sycamore processor has 53 qubits.

• Honeywell and IonQ have developed systems with a few hundred qubits.

While these numbers are impressive, they’re still far from the million-qubit milestone. Reaching a million qubits is a critical milestone because that’s where quantum computers are expected to have the power to solve real-world problems beyond the reach of classical computers.

DARPA’s Quantum Benchmarking Initiative

In January 2023, Microsoft was selected as one of just two companies to advance to the final phase of the DARPA’s US2QC program, part of the U.S. government’s larger Quantum Benchmarking Initiative. This program aims to develop the first utility-scale, fault-tolerant quantum computer — one that can solve useful problems more efficiently than traditional computers while being reliable and resistant to errors.

• The Defense Advanced Research Projects Agency (DARPA): is an R&D agency of the US Department of Defense (DoD) responsible for the development of emerging technologies for use by the military.

• Underexplored Systems for Utility-Scale Quantum Computing (US2QC): The main goal of the US2QC program, which is part of the Quantum Benchmarking Initiative, is to explore and develop new approaches to create utility-scale quantum computers.

Microsoft’s work on topological qubits and its Majorana 1 quantum processor likely played a significant role in securing its spot in this advanced research phase.

When we discuss quantum computing, we often compare it to breakthroughs like EUV lithography, which revolutionized semiconductor technology and computational power. Both have been, and continue to be, national security priorities. In the 1990s, the US Department of Energy funded a program focused on developing new lithography techniques, including EUV, and this is how ASML became the sole provider of EUV lithography after acquiring one of the few companies granted access to the project, SVG. Today, quantum computing is seen in a similar light. Its computational power, rooted in quantum mechanics, is almost beyond comprehension, an area far removed from business school. Currently, the US Department of Defense supports a program called the Quantum Benchmarking Initiative, an R&D effort to advance emerging technologies for military applications. Showcasing how imperative it is for the U.S. to gain foothold in this technology.

The Biggest Challenge: Error Correction and Stability

The most significant challenge in quantum computing today is error correction and qubit stability. Even the smallest disturbance can introduce errors, and qubits are extremely fragile — they can easily lose their quantum state. To overcome this, physicists are working hard to find the best ways to create, stabilize, and maintain qubits — a daunting task in the field.

Microsoft’s Majorana 1 Announcement

Today, Microsoft unveiled Majorana 1, the first quantum chip powered by Topological Core architecture. Now, this is where things start to get a bit tricky. We didn't exactly learn quantum mechanics in business school, but understanding the core concept of qubits gives you a strong foundation in quantum computing — and its biggest challenges.

Majorana fermions are particles that can team up in pairs to store quantum information in a super stable way, so even if something shakes or zaps them, the quantum computer keeps working right. A single qubit can be encoded using two or more Majorana fermions, with the information stored in their combined state rather than in a single particle.

• Why it matters: Because the Majorana fermions are spatially separated, local noise affecting one end of the system doesn’t easily destroy the qubit’s information, which is spread out non-locally. This delocalization adds another layer of protection against errors.

Researchers have been working with hybrid setups, like combining semiconductors and superconductors in tiny wires, to generate and spot Majorana fermions. After twenty years of effort, Microsoft claims to have created a brand-new type of matter by controlling these Majorana particles. These particles could be essential for building the core components of quantum computers, as they’re thought to make qubits— the building blocks of quantum computing—more stable and dependable. This could tackle two big problems in quantum computing: fixing errors and keeping things steady. That’s why Microsoft named its quantum processing unit "Majorana 1."

This announcement is huge because it signifies a major breakthrough in the scalability of quantum computing. Unlike traditional approaches that struggle with error-prone qubits and fragile quantum states, topological qubits are more resistant to disturbances, enabling quantum computers to scale more efficiently and operate with greater precision. By using Majorana particles, Microsoft is not only making quantum computing more feasible but is also paving the way for truly fault-tolerant, large-scale quantum systems. This could accelerate the realization of utility-scale quantum computers capable of solving real-world problems that current classical systems can’t even approach. In short, Majorana 1 isn't just a chip — it's a critical step toward making quantum computing practical and impactful, potentially reshaping industries from drug discovery to climate modeling.