## What is the position operator in momentum space?

In quantum mechanics, the position operator is the operator that corresponds to the position observable of a particle. When the position operator is considered with a wide enough domain (e.g. the space of tempered distributions), its eigenvalues are the possible position vectors of the particle.

**What does the momentum operator do?**

In a basis of Hilbert space consisting of momentum eigenstates expressed in the momentum representation, the action of the operator is simply multiplication by p, i.e. it is a multiplication operator, just as the position operator is a multiplication operator in the position representation.

**How are position and momentum related?**

A position vector defines a point in space. If the position vector of a point particle varies with time it will trace out a path, the trajectory of a particle. Momentum space is the set of all momentum vectors p a physical system can have.

### Do momentum and position operators commute?

Momentum Representation The position and momentum operators do not commute in momentum space. The product of the position‐momentum uncertainty is the same in momentum space as it is in coordinate space.

**What is momentum operator formula?**

In momentum space the following eigenvalue equation holds: ˆp|p⟩=p|p⟩. Operating on the momentum eigenfunction with the momentum operator in momentum space returns the momentum eigenvalue times the original momentum eigenfunction. and that hiddx is the momentum operator in coordinate space.

**How do you find the commutator value?**

The order of the operators is important. The commutator [A,B] is by definition [A,B] = AB – BA. [A,BC] = B[A,C] + [A,B]C and [AB,C] = A[B,C] + [A,C]B. Proof: [A,BC] = ABC – BCA + (BAC – BAC) = ABC + B[A,C] – BAC = B[A,C] + [A,B]C.

## How do you prove a position operator is Hermitian?

Assume we are working in the position representation.

- For ˆx to be Hermitian we must show that:
- Eigenvalues of ˆx are real, x=x∗:
- Thus, ˆx is Hermitian.
- For ˆp to be hermitian we must show the following:
- Thus ˆp is Hermitian.

**Which is the total energy operator?**

Hamiltonian operator

The total energy operator is called the Hamiltonian operator, ˆH and consists of the kinetic energy operator plus the potential energy operator.