Hardware of a Quantum Computer #3 Quantum Materials

• Provide the environment where qubits are defined and live
• High quality materials with desired physical and electronic properties processed through Chemical Vapour Deposition
  • E.g. SiGe (Silicon Germanium) layer on Silicon layer
• Inspect the fabricated heterostructures with high resolution
• Properties of quantum materials
  • Mobility
  • Electron density
• Properties are measured by parameters such as
  • Temperature
  • Electric fields
  • Magnetic fields

DiVincenzo criteria

Necessary properties to be called a quantum computer

• The system must be scalable with well defined qubits
• The computer must have the ability to initialize the state of qubits
• Qubits must have long decoherence times
  • Avoid materials with a complex structure, as it is more likely to interact with the qubits
• The computer must be able to perform a universal set of quantum gates on the qubits

양자컴퓨터에 사용되는 물질들이 가져야할 특징에 대해 알아봤다. 화학과나 물리학과가 아니라서 솔직히 잘 모르겠다. 전기장과 자기장을 이용해 qubit의 state를 excite 하고 measure 하기 때문에 관련된 성질이 중요한 것 같다.

Decoherence time이라는 용어는 이후에도 계속해서 등장한다.

Decoherence time

the length of time the qubits can be entangled without loss of any information

모든 양자연산이 이 시간 내에 완료되어야하기 때문에 긴 decoherence time을 갖는게 중요하다.