What is Superposition?

Superposition is the principle of quantum theory that explains the challenging concept of the behavior and nature of matter at sub-atomic level. According to the principle of superposition, when we don’t know what is the state of any object; it is in all possible states simultaneously until we don’t see to check.


The Double-Slit Experiment

In this experiment, a beam of light is targeted towards an obstacle having two vertical slits. The beam of light is made to pass through the slits, and the pattern formed is recorded on a photographic plate. When one slit is covered, the formed pattern would be a single line that is aligned with slit which is open. The photographic plate is completely separated into many lines of darkness and lightness in different degrees. It illustrates that interference takes place among the waves and particles passing via slits.
The resulting pattern indicates the interference which reveals that the individual particles are interfere with themselves. Since we expect a single photon goes through one slit or the other and end up in one of the two light areas. But this does not happen.

Feynman concluded that each photon along with going through both slits simultaneously takes all the possible trajectories to the target.

The Experiment mainly concentrates on tracking the paths of every photon individually. Here the measurement disrupts the trajectories of photons, and the results becomes what is based on classical physics, i.e., two bright lines are aligned to the slits of the barrier. The pattern again becomes multiple lines in different degrees of darkness and lightness.

Every photon moves in a superposition of possible parameters simultaneously, and measurement of the path makes the superposition of states to a single position.


At the quantum scale, particles can be considered as waves. They can be in different states, for example, they can be in different positions, differ in energies or moving at different speeds. If you think about particles, it means that a particle can exist in two places at once. This doesn’t make much sense but is a part of quantum physics.However, once a particle is measured, for example, its energy or position is known, the superposition doesn’t exist, and we have a particle in one known state.

Practise This Question

An ac source is connected to a resistive circuits. Which of the following is true