Kenji sends one photon toward a card with two slits. Two things could happen next: the photon goes through the left slit, or it goes through the right slit. Quantum physics has a tidy way to talk about possible conditions like these.
Light comes in photons, and matter particles show wave-particle duality too. This lesson names the objects quantum physics talks about, and the conditions those objects can be in.
A photon is not the only thing that needs both pictures. Electrons do too, and so do other matter particles.
A photon, or a matter particle showing wave-particle duality, is called a quantum object.
A quantum object can be in different possible conditions. It can take a particular path. It can sit at a particular position. It can have a particular energy.
Kenji's photon has two path conditions on offer: 'went through the left slit' and 'went through the right slit'. Those are two quantum states of one photon.
A quantum state belongs to its object. Two states of one photon are not two photons; they are two conditions the same photon could be in.
The next lessons lean on these two names: quantum object and quantum state.
Marisol's electron could be at a low energy or at a high energy. How does quantum physics describe these two conditions?
The electron is a matter particle showing wave-particle duality, so it is a quantum object.
Each possible condition of a quantum object is a quantum state.
'At a low energy' and 'at a high energy' are two quantum states of the one electron.
They are two quantum states of one quantum object, Marisol's electron.
Soraya lists 'the photon itself' as one of a photon's quantum states. What is wrong with her list?
A quantum state is a possible condition of an object: a path, a position, or an energy.
The photon is the object that has the conditions. It is not itself a condition.
A right list for a photon at two slits is 'went through the left slit' and 'went through the right slit'.
The photon is the quantum object, not a quantum state; its states are its possible conditions.
Which of the following is a quantum object?
Jocasta's photon could reach a detector by an upper path or by a lower path. What are 'took the upper path' and 'took the lower path'?
Soraya says: 'A quantum state is one possible condition a quantum object can be in, such as a path, a position, or an energy.' Is Soraya correct?
Which statement says what a quantum state is?
A photon heading for a half-silvered mirror could pass through it or reflect off it. How does quantum physics count these two conditions?
Which of the following could be a quantum state of a single electron?