Several Ways to Implement Qubits in Physics

In order to achieve quantum computation, the qubit preparation is crucial, given that the performance relies on various gate operations, which is determined by the quality of qubit. This paper introduces many qubits, including atoms (neutral atoms and ions) and spins (quantum dots, diamond NV centers, and nuclear magnetic resonance) that depend on various systems. Moreover, they are mentioned separately in this paper due to the significance of superconducting qubits. Meanwhile, the advantages and drawbacks of these qubits are compared, e.g. their coherence (long coherence time between neutral atoms and ions), operating temperature, quantum state reading, quantum system ease of handling, and precision of handling. Challenges as well as corresponding resolved methods have been addressed and reviewed. Current gaps and limitations are also discussed.