Microsoft and the Topological Qubit

Msoft Says it will arrive, and it will even scale.

Microsoft announces progress on a completely new type of qubit

Topological qubits don't exist yet, but the company is convinced they'll scale.

JOHN TIMMER - 3/15/2022,     In Arstechnica

So far, two primary quantum computing technologies have been commercialized. One type of hardware, called a transmon, involves superconducting wire loops linked to a resonator; it is used by companies like Google, IBM, and Rigetti. Companies like Quantinuum and IonQ have instead used individual ions held in light traps. At the moment, both technologies are in an awkward place. They've clearly been demonstrated to work, but they need some significant scaling and quality improvements before they can perform useful computations.

It may be a bit surprising to see that Microsoft is committed to an alternative technology called "topological qubits." This technology is far enough behind other options that the company just announced it has worked out the physics to make a qubit. To understand Microsoft's approach better, Ars talked to Microsoft engineer Chetan Nayak about the company's progress and plans.

The foundation of a qubit

Microsoft is starting behind some competitors because the basic physics of its system weren't entirely figured out. The company's system relies on the controlled production of a "Majorana particle," something that was only demonstrated to exist within the last decade (and even then, its discovery has been controversial).

The particle gets its name from Ettore Majorana, who proposed the idea back in the 1920s. In the simplest terms, a Majorana particle is its own antiparticle; two Majorana particles that differ in their spin would annihilate if they met. So far, none of the known particles appears to be a Majorana particle (all but neutrinos definitively aren't). But the concept has endured because of the prospect of making Majorana quasiparticles, or a collection of particles and fields that, in certain contexts, behaves as if it were a single particle.

The most prominent quasiparticle is probably the Cooper pair, in which two electrons are paired in a way that alters their behavior. Cooper pairs are necessary to get superconductivity to work.  .... '