How Do You Find Wavefunctions from Given Quantum States?

In summary, the problem involves finding the wavefunctions for two states of the electro-magnetic field, one of which is a pure state and the other is a mixed state described by a density matrix. While the second state does not have wavefunctions, the first state can be represented by a wavefunction multiplied by a random phase variable. The task is to find the photon number distributions for both states.
  • #1
bekjunhao
6
0

Homework Statement



Given state: |ψ> = |0> + α|1> + σ^2/√2 |2>

find the wavefunctions.


I am confused between states and wavefunctions, everywhere I've read it says that state (ie the wavefuctions), really need some enlightenment here..
 
Physics news on Phys.org
  • #2
bekjunhao said:

Homework Statement



Given state: |ψ> = |0> + α|1> + σ^2/√2 |2>

find the wavefunctions.


I am confused between states and wavefunctions, everywhere I've read it says that state (ie the wavefuctions), really need some enlightenment here..

Can you post the entire problem statement verbatim (word for word) as it is given to you?
 
  • #3
Consider the two states of the electro-magnetic field

|ψ> = |0> + α|1> + σ^2/√2 |2>
ρ = 3/8((|0>+|1>(<0|+<1|)) + 1/4 |0><0|

where |n>, n= 0, 1, 2 are Fock states

find the photon number distributions and the wavefunctions for the two states
 
  • #4
So i understand for the second state there wouldn be any wavefunctions as it is a mixed state.

The first state however is a pure state, so i went like x|ψ> . But after that I am stuck, any hints so that i can continue?
 
  • #5
bekjunhao said:
So i understand for the second state there wouldn be any wavefunctions as it is a mixed state.

The first state however is a pure state, so i went like x|ψ> . But after that I am stuck, any hints so that i can continue?

What do you mean the second state? [itex]\hat{\rho}[/itex] is the density matrix, not a state.
 
  • #6
Eh I think it's confusing with the notations used in the question.. But it isint the density matrix... Just a mixed state
 
  • #7
bekjunhao said:
Eh I think it's confusing with the notations used in the question.. But it isint the density matrix... Just a mixed state

Technically, it's the density matrix that describes the mixed state. The state cannot be represented by a wavefunction (unless you include an additional random phase variable, which, if you haven't learned about in class, you probably needn't worry about), but you can still find the photon number distributions. Have you done that?

It seems odd to me to ask for the wavefunctions of the two states, especially without specifying a basis, maybe I'm just not seeing the point of the question. Hopefully someone else will weigh in here.
 

FAQ: How Do You Find Wavefunctions from Given Quantum States?

What is a wavefunction and why is it important in quantum mechanics?

A wavefunction, also known as a quantum state, is a mathematical function that describes the quantum state of a particle or system. It contains information about the probability of finding the particle in a particular state, as well as other physical properties. In quantum mechanics, the wavefunction is crucial in understanding the behavior of particles at the microscopic level.

How do you find the wavefunction given a set of states?

To find the wavefunction, you need to solve the Schrödinger equation, which is a differential equation that describes the evolution of a quantum system. The solution to this equation is the wavefunction, which can be found by using mathematical techniques such as separation of variables, perturbation theory, or numerical methods.

What are the different types of states that can be used to find the wavefunction?

There are two main types of states that can be used to find the wavefunction: eigenstates and superposition states. Eigenstates are stationary states with definite energy levels, while superposition states are a combination of multiple eigenstates with different energies. By using a linear combination of eigenstates, any wavefunction can be constructed.

Can the wavefunction be measured or directly observed?

No, the wavefunction itself cannot be measured or directly observed. It is a mathematical construct that describes the quantum state of a particle or system. However, the properties and behavior of the particle can be observed and measured based on the information contained in the wavefunction.

What are the limitations of finding wavefunctions given states?

One limitation is that the Schrödinger equation can only be solved analytically for simple systems with known potentials. For more complex systems, numerical methods must be used, which can be computationally demanding. Additionally, the wavefunction only describes the behavior of a single particle or system, and cannot account for interactions with other particles or external factors.

Back
Top