In a real-world situation, qubits, which are the fundamental units of quantum information, can be created using various physical systems that exhibit quantum properties. Here are a few examples of how qubits are created:
Superconducting Circuits: Superconducting qubits are created using tiny circuits made from superconducting materials. These circuits are cooled to extremely low temperatures, close to absolute zero, to exploit quantum effects. The qubits are typically formed by creating artificial atoms, called transmons, which can be controlled and manipulated to represent the quantum states of 0 and 1.
Trapped Ions: Qubits can be created using individual ions that are trapped and manipulated using electromagnetic fields. By using laser beams to manipulate the internal energy levels of these ions, researchers can encode and process quantum information.
Topological Qubits: Topological qubits are based on exotic states of matter that emerge in certain materials, such as topological superconductors. These qubits rely on the non-local properties of the material and are less sensitive to noise and environmental disturbances.
Quantum Dots: Quantum dots are tiny semiconductor structures that can confine individual electrons. By controlling the confinement and energy levels of these electrons, researchers can create qubits. Quantum dots can be formed using various materials, such as silicon or gallium arsenide.
Photons: Qubits can also be encoded in the properties of individual photons, the particles of light. For example, the polarization or the path of a photon can be used to represent the quantum states of 0 and 1.
As for current examples, there are ongoing efforts in both academia and industry to create and harness qubits for practical quantum computing and other quantum technologies. Some prominent examples include:
IBM Q: IBM has been actively developing and improving superconducting qubits, which are accessible through their cloud-based quantum computing platform, IBM Q. Researchers and developers can access these qubits to experiment and develop quantum algorithms.
Google's Sycamore: Google's research team demonstrated quantum supremacy in 2019 using a 53-qubit superconducting quantum processor called Sycamore. They performed a calculation that would be practically infeasible for classical computers, showcasing the potential of quantum computation.
IonQ: IonQ is a company that focuses on trapped-ion qubits. They have developed trapped-ion quantum processors with a large number of qubits and have made their systems available to selected partners for testing and development purposes.
Microsoft's Station Q: Microsoft has been exploring the use of topological qubits for quantum computing. Their Station Q research group is dedicated to the study and development of topological qubits, aiming to build a robust and scalable quantum computer.
These examples represent just a fraction of the ongoing research and development in the field of quantum computing, and many other organizations and research groups worldwide are actively working on creating qubits and advancing quantum technologies.