Majorana Fermion

If you met your antimatter twin, you’d both annihilate in a burst of pure energy!

Why do Majorana fermions matter, and how could they revolutionize computing?

• 400 years ago, Galileo started piecing together the basic principles of reality – modern science.
• ever since thousands of theories and experiments have peered into smaller and smaller distances converging on a single picture of the structure of matter – the standard model.
• The standard model of particle physics is often hailed as the most successful scientific theory of all time.
• It has correctly predicted the existence of particles, three of the four known fundamental forces (electromagnetic, weak and strong interactions – excluding gravity) in the universe.
• It has described the most basic building blocks of the universe by classifying all known elementary particles.
• Gravity is the most obvious force at play in the world around us and yet, in many sense the one we understand least.
• We do have a theory of gravity, given to us by Albert Einstein – General relativity – there are 2 reasons why it is not included in the standard model.
  • at the microscopic level, the force of gravity is so weak that it barely has any effect on a single subatomic particle.
    • we don’t really know how to incorporate general relativity which is a classical theory into the Quantum world – we have no idea to peer into a black hole where quantum gravity effects are at work.
  • the standard model is written in quantum field theory language – this tells us that matter at the fundamental level, is not really made up of particles – it’s made up of fluke-like objects which are spread through all of space – engaged in an intricate, harmonious dance to a music we call the laws of physics.
    • the interactions between the fields produce the physical world in the form of particles.
• To understand the standard model, it’s convenient to use the language of particles.
• As we build up the standard model, one classification is by far the most important – every particle is
  • a fermion – which is a matter particle.
  • a boson – which is a force particle.
• the distinction between fermions and bosons lies in the quantum world, fermion must obey the Pauli exclusion principal – which means you can’t put two fermions on top of each other in space – these are the building blocks of matter.
• bosons on the other hand can pile onto of each other as much as they want as they are not bound to obey the Pauli exclusion principal.
• Everything we are made of can be reduced to three matter particles: an electron, up quark, down quark.
• the familiar neutron and proton each contain three quarks – a proton has 2 up quarks and a down, a neutron has 2 down quarks and a up – put a proton and neutron together and you have a nucleus, add an electron into the mix and you have an atom, put atoms together and that is what we are made of.
• Most sub-atomic particle in nature have their own antiparticle – a corresponding antiparticle with the same mass but opposite charge. i.e Electron (e⁻) have Positron (e⁺), Proton (p⁺) have Antiproton (p⁻), and Neutron (n) have Antineutron (n̅) – when matter and antimatter come into contact, they annihilate, releasing pure energy in the form of gamma rays.
• But Majorana fermions are different. They are their own antiparticles, meaning they can exist in a bizarre state where a particle is indistinguishable from its antimatter twin. This makes them incredibly unique and difficult to detect.
• In 1937 Ettore Majorana proposed that there might be a special case where particles behave as their own anti-particles – they must have neutral charge and obey real value field.
• Majorana suggested that chargeless fermions could be described by a real wave equation, leading to the possibility that this particle would be identical to its antiparticle.
•  If fermions and anti-fermions were indeed indistinguishable, they could co-exist without annihilating one another – not something that we seem to see in nature. However, recent experiments have indicated the existence of these particles within condensed matter systems. If further data bears this out, it could lead to myriad applications in fields as diverse as quantum computing and cosmology.
• Majorana particles should make stable qubits – In certain quantum systems (like superconductors), Majorana fermions behave non-traditionally, meaning their quantum states “braid” around each other instead of just switching places – By moving and braiding these states around each other, they can perform quantum computations.
• This makes them useful for topological quantum computing.
• A normal computer works by handling bits that are in one of two states (0 or 1). In comparison, quantum states can be a superposition. So instead of using bits of only two states, a quantum computer manipulates information as qubits, which can be a superposition of many states. As a quantum computer can simultaneously contain multiple states it can theoretically perform millions of times more operations than a normal computer.
• If fully realized, Majorana fermions could revolutionize quantum computing by enabling error-resistant, scalable qubits, bringing us closer to practical quantum computers. Major tech companies and research institutions (such as Microsoft) are actively working on this approach.