GS 3 – SCIENCE AND TECHNOLOGY
Context
- In the race for practical quantum computers, scientists are exploring exotic particles like Majorana fermions (particles that are their own antiparticles).
- Proposed in the 1930s by Ettore Majorana, these particles have unique properties that may help overcome one of quantum computing’s hardest challenges — noise and decoherence.
What are Majorana Particles?
- Ordinary particles:
- Electrons/protons ≠ their antiparticles.
- Matter + antimatter = annihilation.
- Majorana particles:
- Perfect mirror of themselves (particle = antiparticle).
- Rare symmetry; long considered theoretical.
- Quasiparticles in condensed matter:
- In certain superconductors at near absolute zero, electron states split into Majorana modes at wire ends.
- These behave mathematically like Majorana particles.
Why Are They Important for Quantum Computing?
- The Problem of Decoherence
- Qubits exist in fragile superpositions (0 + 1 simultaneously).
- Interaction with environment → collapse of state (decoherence).
- Current superconducting qubits last only micro- to milliseconds.
- Solution today = quantum error correction → requires hundreds/thousands of physical qubits for 1 logical qubit (high overhead).
- Majorana Advantage
- Nonlocal encoding:
- One qubit stored across two distant Majorana modes.
- Local disturbances affect only one half, leaving info intact.
- Topological protection (Braiding property):
- Majoranas are non-Abelian anyons.
- Exchanging them changes the joint state in a way that depends only on the braid pattern, not physical details.
- Makes operations naturally resistant to noise and small errors.
Practical Benefits
- Potentially far fewer qubits needed (lower error-correction overhead).
- More stable and scalable quantum computers.
- Simplified hardware vs. current superconducting/trapped ion systems.
- Could enable computations impossible with today’s noisy devices.
Challenges
- Proof still pending: experiments have shown signals consistent with Majoranas, but skeptics say other effects can mimic them.
- Braiding demonstration (moving modes around each other) not yet conclusively achieved.
- Requires precise materials: nanowires (e.g., indium antimonide) + superconductors + magnetic fields.
- Major risks: quasiparticle poisoning, imperfect isolation, dimensional constraints.