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One of the biggest challenges in quantum computing is decoherence — the tendency of qubits to lose their fragile quantum state due to environmental noise. To address this, scientists are exploring the potential of Majorana particles, exotic entities that are their own antiparticles. Their unique quantum properties may help build topological qubits, inherently resistant to errors, offering a radically new path toward practical quantum computing.

What are Majorana Particles?

• Proposed by: Italian physicist Ettore Majorana in 1937.
• Nature: A hypothetical fermion that is its own antiparticle, unlike electrons or protons which have distinct antimatter counterparts.
• Key Characteristics:
  • Neutral in charge, hence elusive in detection.
  • Do not annihilate on contact with themselves.
  • In condensed-matter systems, they appear as quasiparticles (collective excitations) inside superconductors at ultra-low temperatures.
  • Often exist in pairs: two spatially separated halves forming one quantum state.
  • Exhibit non-Abelian statistics, meaning that exchanging or “braiding” them changes the overall quantum state in a predictable but unusual way.

Relevance to Quantum Computing

• Problem of Decoherence
  • Qubits (quantum bits) exist in superpositions of 0 and 1, but are easily disturbed by external noise.
  • Current quantum error correction requires hundreds to thousands of physical qubits to stabilise a single logical qubit, making scaling inefficient.
• Majorana-Based Solution
  • Information can be encoded nonlocally across two Majorana modes.
  • Disturbance of one half does not collapse the qubit; both must be affected simultaneously, making errors less likely.
  • Braiding Majoranas enables topologically protected operations, where outcomes depend only on the braiding pattern and not on experimental imperfections.
  • This reduces the need for massive error correction, making quantum hardware simpler and more stable.
• Current Research
  • Experiments in superconducting nanowires (e.g., indium antimonide) have shown conductance patterns consistent with Majorana modes.
  • However, alternative explanations exist, and conclusive proof requires demonstrating controlled braiding.

Wider Implications

• Quantum Technology: Potential to drastically lower the qubit requirement for large-scale quantum computers.
• Particle Physics: Ongoing efforts to test whether fundamental particles like neutrinos could be Majorana fermions.
• Condensed Matter Physics: Research into Majoranas has advanced material science, superconductors, and nanotechnology.

Challenges

• Experimental signals remain inconclusive, as other phenomena can mimic Majorana-like behaviour.
• Braiding demonstrations in two-dimensional architectures remain technically difficult.
• Majorana-based qubits are still at the proof-of-concept stage, not yet integrated into practical computing systems.