Microsoft’s Majorana 1: world’s first quantum processor powered by topological qubits

 Quantum computing is an emergent field of cutting-edge computer science harnessing the unique qualities of quantum mechanics to solve problems beyond the ability of even the most powerful classical computers. A quantum computer is a computer that exploits these quantum mechanical phenomena to compute much faster and efficiently than modern computers. At the World Governments Summit in Dubai last week, Google CEO Sundar Pichai said that quantum computers are what AI was for us 10 years ago. It’s the future and the next big leap in technology everyone is waiting for.

On February 19 Microsoft today introduced Majorana 1, the world’s first quantum chip powered by a new Topological Core architecture that it expects will realize quantum computers capable of solving meaningful, industrial-scale problems in years, not decades.

It leverages the world’s first topoconductor, a breakthrough type of material which can observe and control Majorana particles to produce more reliable and scalable qubits, which are the building blocks for quantum computers. In  the same way that the invention of semiconductors made today’s smartphones, computers and electronics possible, topoconductors and the new type of chip they enable offer a path to developing quantum systems that can scale to a million qubits and are capable of tackling the most complex industrial and societal problems.

This new architecture used to develop the Majorana 1 processor offers a clear path to fit a million qubits on a single chip that can fit in the palm of one’s hand, Microsoft said. This is a needed threshold for quantum computers to deliver transformative, real-world solutions such as breaking down microplastics into harmless byproducts or inventing self-healing materials for construction, manufacturing or healthcare. All the world’s current computers operating together can’t do what a one-million-qubit quantum computer will be able to do. 

“Whatever you’re doing in the quantum space needs to have a path to a million qubits. If it doesn’t, you’re going to hit a wall before you get to the scale at which you can solve the really important problems that motivate us,” They said.  “We have actually worked out a path to a million.”

The topoconductor, or topological superconductor, is a special category of material that can create an entirely new state of matter not a solid, liquid or gas but a topological state. This is harnessed to produce a more stable qubit that is fast, small and can be digitally controlled, without the tradeoffs required by current alternatives. 

Harnessing a new type of material

Microsoft built the world’s first topoconductor. This revolutionary class of materials enables us to create topological superconductivity, a new state of matter that previously existed only in theory. The advance stems from their innovations in the design and fabrication of gate-defined devices that combine indium arsenide (a semiconductor) and aluminum (a superconductor). When cooled to near absolute zero and tuned with magnetic fields, these devices form topological superconducting nanowires with Majorana Zero Modes (MZMs) at the wires’ ends.

For nearly a century, these quasiparticles existed only in textbooks. Now can be created and controlled  on demand using topoconductors. MZMs are the building blocks of our qubits, storing quantum information through ‘parity’ whether the wire contains an even or odd number of electrons. In conventional superconductors, electrons bind into Cooper pairs and move without resistance. Any unpaired electron can be detected because its presence requires extra energy. Microsoft's topoconductors are different: here, an unpaired electron is shared between a pair of MZMs, making it invisible to the environment. This unique property protects the quantum information.

Revolutionizing quantum control through digital precision

This readout technique enables a fundamentally different approach to quantum computing in which measurements are used to perform calculations.

Traditional quantum computing rotates quantum states through precise angles, requiring complex analog control signals customized for each qubit. This complicates quantum error correction (QEC), which must rely on these same sensitive operations to detect and correct errors.

Measurement-based approach simplifies QEC dramatically. Microsoft performed error correction entirely through measurements activated by simple digital pulses that connect and disconnect quantum dots from nanowires. This digital control makes it practical to manage the large numbers of qubits needed for real-world applications.

From physics to engineering

With the core building blocks now demonstrated quantum information encoded in MZMs, protected by topology, and processed through measurements they moved from physics breakthrough to practical implementation.

The next step is a scalable architecture built around a single-qubit device called a tetron. At the Station Q meeting, they shared data demonstrating the basic operation of this qubit. One fundamental operation measuring the parity of one of the topological nanowires in a tetron.

Another key operation puts the qubit in a superposition of parity states. This, too, is performed by a microwave reflectometry measurement of a quantum dot, but in a different measurement configuration in which we decouple the first quantum dot from the nanowire and connect a different dot to both nanowires at one end of the device. By performing these two orthogonal Pauli measurements, Z and X, they demonstrated measurement-based control a crucial milestone that unlocks the next steps on our roadmap.

This led them systematically toward scalable QEC. The next steps involved a 4×2 tetron array. We will first use a two-qubit subset to demonstrate entanglement and measurement-based braiding transformations. Using the entire eight-qubit array, then implementing quantum error detection on two logical qubits.

The built-in error protection of topological qubits simplifies QEC. Moreover, our custom QEC codes reduce overhead roughly tenfold compared to the previous state-of-the-art approach. This dramatic reduction means that the scalable system can be built from fewer physical qubits and has the potential to run at a faster clock speed.

Quantum computing could have a significant impact on everyday life. For instance, it can revolutionize medicine and drug discovery by simulating molecules and chemical reactions in ways that classical computers cannot. It could solve climate change problems by helping scientists develop more efficient solar panels, batteries, and carbon capture technologies. It is also believed to contribute to the advancement of AI, which can be a dramatic improvement, by making it a lot more efficient, accurate, and capable of solving much more complex problems like predicting natural disasters or optimising traffic systems in real-time.