What Makes Quantum Properties Possible - RPIQuantumComputing/QuantumCircuits GitHub Wiki

Wave properties: Waves, such as light and water waves, travel with a unique velocity. Further, waves interact with each other to form complex patterns in a process called interference. Sometimes waves can add onto each other to create a bigger wave (constructive interference), and sometimes waves can cancel each other out (destructive interference).

Particle properties: Particles have mass, a definite, discrete location, and also travel with a certain velocity. Anything that can be measured consistently in a particle is called a particle property.

Double-slit experiment: The double-slit experiment helps visualize the differences between waves and particles. In this experiment, the wave or particle is aimed at two slits, behind which is a plain wall. Particles pass through either the left or the right slit, and create two lines of discrete spots on the wall. Waves passing through the slits interfere with each other and create a pattern of bright and dark lines on the wall.

Explanation:

Wave-particle duality: Quantum objects show both wave-like and particle-like properties. When quantum objects, such as photons and electrons, are used in a double slit experiment, they create discrete spots (like particles) but the spots are arranged in an interference pattern (like waves). Because of wave-particle duality, we can think of qubits as both waves and particles.

Superposition with waves: Superposition stems from wave-particle duality. Using the wave nature of qubits, we can represent the two states of the qubit (0 and 1) with two waves. To create a superposition state, we can combine these waves.

Interference with waves: Interference also stems from wave-particle duality, and can be described as the addition or subtraction of the waves representing qubit states. Both superposition and interference involve overlap between waves.

Discretization with waves: The discreteness of the quantum world comes into play when quantum objects are confined. Confinement of waves forces them to only take certain shapes or energies. In the quantum world, confinement can exist naturally or artificially.

• Ex. in a trapped ion qubit, where the negatively charged electron is confined by the positively charged nucleus.
• Ex. such as through electric circuits in superconducting qubits.