The giant software company, Microsoft argues that building a quantum computer based on Majorana zero modes will bypass error correction issues and speed up fault-tolerant quantum computing at scale. As of this month, I have not seen new paperwork to indicate a time frame for a proof of concept, but they claim they have reached a critical milestone in developing a new kind of physics. This short post attempts to uncover the idea behind the topological quantum information calculation, storage and retrieval system proposed by Microsoft. If and when it happens, MS claims to offer the most powerful quantum computer ever built.
So the current generation of quantum computers are known as noisy intermediate scale quantum devices or NISQ devices. And these typically rely on encoding quantum information in the individual quantum states of quantum particles. So anything from the excited state of ions, cold atoms, NV diamonds to photons, electrons, things like that used by current state of the art; for example IonQ and Honeywell. And, these particles are readily available, given to use by nature; we can manipulate them relatively easily using laser technology today. These devices getting smaller and more fault-tolerant, and we're seeing some inspiring new applications and ideas coming through.
So Microsoft decided to take a slightly different approach; It all started with a 1937 paper from Ettore Majorana was an Italian theoretical physicist working in the 1920s and 30s who was regarded as a prodigy of his generation. Find and control the Majorana particles and use them to build the Quantum computer at scale!
So before we delve briefly into the concept, we should talk about a Microsoft Scientist in charge of Microsoft Quantum platform; Michael Freedman. So, Michael Freedman is an American mathematician, at Microsoft Station Q. In 1986, he was awarded a Fields Medal for his work on the 4-dimensional generalized Poincaré conjecture. He and his team claim they have found the Majorana zero mode.
So, based on a paper from 1937, Michael Friedman argued that if there was a way to leverage topological properties to encode quantum information rather than using the individual quantum properties of these kinds of single like electrons or ions. See this link for more about Michael Friedman.
To do that, he had to prove the concept behind 1937 paper. Now, the idea behind that is that by encoding information in a topological property, it should be more resilient to noise, and 85 years later, MS has proved it, reaching a monumental milestone and inventing a new physics.
But what is a topological platform? What does that mean?
So the way it works is you get these nanowires, which is the indium arsenide aluminum hybrid ( also known as *indium aluminium arsenide or AlInAs (AlxIn1−xAs), is a semiconductor material with very nearly the same lattice constant as GaInAs, but a larger bandgap,) cool them down to nearly zero Kelvin, for example, millikelvin. And at the super low temperatures, the electrons in this material behave weirdly, so you can almost think of it like they're lining up in kind of a little chain of electrons. And they put a electron cap on each end of these chains.
Instead of encoding information in the states with these individual electrons or ions, they braid the nanowires . So these chains, and you kind of think of it, like if you got a bunch of strings and braid them together, or tie the knot in them. And then you kind of shake it around. That perturbation and shaking doesn't affect the information you've encoded in that braided pattern or that not anywhere near as much as if we were encoding that in the state of an individual string. This will solve the error correction problem facing the current generation of Quantum devices.
So the idea behind a topological qubit is that by using this braiding scheme, by encoding information and topological properties, they can leapfrog a lot of the problems that are the reason that we don't have fully scaled quantum computers today, namely decoherence, which the quantum particles are incredibly susceptible to noise from the environment.
The March 2022 paper was an incredible milestone. So what they achieved is that the Microsoft station Q team managed to create and control these Majorana zero modes after 85 years. And this is the fundamental building block that Microsoft can now take forward and start building these topological qubits.
So, what is next?
Next is to build one qubit and then 2 qubits and build gates and prove that they can do gates with these Majorana zero modes. If they can do that, building the device at scale will be done within next two years. The two year mark is my idea not the Microsoft. Who knows? It may be sooner than later.
I often wonder what Ettore Majorana would think if he was alive.
indium arsenide nanowires :
indium arsenide:
https://en.wikipedia.org/wiki/Indium_arsenide
A Semiconductor Nanowire-Based Superconducting Qubit:
*Indium arsenide is used for construction of infrared detectors, for the wavelength range of 1–3.8 µm. The detectors are usually photovoltaic photodiodes. Cryogenically cooled detectors have lower noise, but InAs detectors can be used in higher-power applications at room temperature as well.
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