Topological quantum computer

A topological quantum computer is a theoretical quantum computer proposed by Russian-American physicist Alexei Kitaev in 1997.[1] It employs quasiparticles in two-dimensional systems, called anyons, whose world lines pass around one another to form braids in a three-dimensional spacetime (i.e., one temporal plus two spatial dimensions). These braids form the logic gates that make up the computer. The advantage of a quantum computer based on quantum braids over using trapped quantum particles is that the former is much more stable. Small, cumulative perturbations can cause quantum states to decohere and introduce errors in the computation, but such small perturbations do not change the braids' topological properties. This is like the effort required to cut a string and reattach the ends to form a different braid, as opposed to a ball (representing an ordinary quantum particle in four-dimensional spacetime) bumping into a wall.

While the elements of a topological quantum computer originate in a purely mathematical realm, experiments in fractional quantum Hall systems indicate these elements may be created in the real world using semiconductors made of gallium arsenide at a temperature of near absolute zero and subjected to strong magnetic fields.

Microsoft is the only major technology company with a history of research and development in topological quantum computing.[2][3]

In 2023, Microsoft researchers published a paper in Physical Review that described a new device that can represent a logical qubit with hardware stability, measuring a phase of matter consistent with the observation of topological superconductivity and Majorana zero modes.[4] The scientists reported that "such devices have demonstrated low enough disorder to pass the topological gap protocol, proving the technology is viable.”[5]

  1. ^ Kitaev, Alexei (9 July 1997). "Fault-tolerant quantum computation by anyons". Annals of Physics. 303 (1): 2–30. arXiv:quant-ph/9707021v1. Bibcode:2003AnPhy.303....2K. doi:10.1016/S0003-4916(02)00018-0. S2CID 11199664.
  2. ^ Pires, Francisco (20 March 2022). "Microsoft Chooses Exotic "Topological Qubits" as Future of Quantum Computing". Tom's Hardware. Retrieved 1 July 2024.
  3. ^ Gibney, Elizabeth (21 October 2016). "Inside Microsoft's quest for a topological quantum computer". Nature. Retrieved 1 July 2024.
  4. ^ Aghaee, Morteza (21 June 2023). "InAs-Al hybrid devices passing the topological gap protocol". Phys. Rev. B. 107 (24): 245423. arXiv:2207.02472. Bibcode:2023PhRvB.107x5423A. doi:10.1103/PhysRevB.107.245423.
  5. ^ Yirka, Bob (24 June 2023). "Microsoft claims to have achieved first milestone in creating a reliable and practical quantum computer". Phys.org. Retrieved 1 July 2024.