Microsoft Corp. today debuted the Majorana 1, an eight-qubit chip that it touts as a major breakthrough in quantum computing.

The processor is powered by quasiparticles called Majorana zero modes. Qubits made from such quasiparticles are less susceptible to errors than other quantum circuits.

As a result, Microsoft believes Majorana 1’s architecture could hold the key to building large-scale quantum computers. The chip is the fruit of a research effort that the company launched nearly two decades ago. 

“Microsoft’s quantum processor news is a significant advance in quantum hardware and reflects the company’s 20-year commitment to scientific research and willingness to take on a very difficult challenge,” said Enrique Lizaso Olmos, co-founder and chief executive of quantum software startup Multiverse Computing.

A quasiparticle is a group of particles or another physical phenomenon that behaves like a single particle. Microsoft’s Majorana 1 chip relies on quasiparticles to represent the ones and zeros it uses in calculations. According to the company, processing is carried out by so-called topological qubits based on a combination of semiconducting and superconducting materials.

Each of the Majorana 1’s qubits is built around a nanowire, or thin wire, made from a superconducting alloy called indium arsenide. This nanowire is connected to a piece of aluminum. By cooling the aluminum to near absolute zero, Majorana 1 can create superconductivity in the indium arsenide nanowire. Superconductivity is a phenomenon that allows electric current to pass through a material without losing energy.

After the qubit becomes superconductive, electrons start to form at the interface between its indium arsenide nanowire and aluminum component. Most of the new particles turn into electron pairs called Cooper pairs.

When there’s an uneven number of electrons, the surplus electron that can’t be paired moves into the nanowire. This surplus particle subsequently turns into Majorana zero modes, the quasiparticles that Microsoft’s quantum chip uses to perform processing.

Each of the chip’s qubits contains two nanowires linked together by a third wire. They’re placed next to a quantum dot, a small semiconducting crystal. This crystal is used to read the data in the qubit. 

The process of creating Majorana zero modes in a qubit changes the nearby quantum dot’s capacitance, or its ability to hold electricity. This change can be measured, which is what makes it possible to read the information in the circuit. The measurement process involves projecting microwaves onto the quantum dot and analyzing how they bounce back.

The main benefit of the Majorana 1’s architecture is reliability. Current quantum chips are highly prone to processing mistakes, which makes them impractical for commercial use. Microsoft’s topological qubits make mistakes at a far lower frequency of once every millisecond or so. 

“This is truly an advance for the industry: building a custom chip that uses topological qubits which many consider extremely useful for scaling to powerful quantum computers,” said Markus Pflitsch, founder and CEO of quantum technology company Terra Quantum AG. “The announcement reinforces our assessment that fault-tolerant quantum hardware is closer than many business leaders think.”

Majorana 1 features eight qubits. According to Microsoft, its quasiparticle-powered qubit architecture design “offers a clear path to fit a million qubits on a single chip” in the future. A processor with 1 million qubits could significantly outperform today’s quantum machines.

Photo: Microsoft