# Questions tagged [quasiprobability-distributions]

The tag has no usage guidance.

21 questions
Filter by
Sorted by
Tagged with
1 vote
59 views

### Phase distribution of coherent states

I am studying the phase distribution for coherent states, as is defined in quantum optics. (See, for example, Introductory Quantum Optics by Gerry and Knight, pages 46–48). In this situation, we seek ...
860 views

### Distributions "more singular than a Dirac delta" must have negativity

I am looking at properties of the Glauber P-functions, which are distributions (in the sense of a dirac delta) on the complex plane, normalized so that $\int_{\mathbb{C}} d^2 \alpha P(\alpha) = 1$. On ...
56 views

### Is it possible to relate the expectation values of an operator w.r.t. two different density matrices if the matrices are related up to a displacement?

I'm trying to derive a general relationship between the expectation values of two different operators with respect to some unspecified state $E_{j}(\lambda)=\mathrm{Tr}[\rho \hat{O}_{j}(\lambda)]$ (...
5k views

### Do we actually need negative probabilities in quantum mechanics?

I was reading this thread and I'm a bit confused. The answer says negative probabilities can account for destructive wave interference and the events cancelling out. But if events just cancel out, ...
46 views

### Is there a way to find the superposition of two Wigner functions without finding their density operators?

Say I have two Wigner functions $W_1(x,p)$ and $W_2(x,p)$ representing pure states on optical phase space, and I want to know what the Wigner function of their superposition $W_{1+2}(x,p)$ looks like (...
187 views

### Intuitively, why does Quantum Mechanics involve a sum over all possibilities?

I understand that one can just mathematically derive the path integral from the Schrodinger equation. I'm looking for an intuitive explanation in contrast with classical mechanics. Consider a ...
68 views

### Is there a relationship between the phase space path integral and phase space quantum mechanics?

I understand that they're, in the end, related because they're the same theory. But is there a closer relationship because both are theories of probability distributions on phase space? I also ...
40 views

### The first non-classical property of field state

In quantum optics, the first non-classical property of the field is squeezing. The reason we say non-classical is that the some of the quasiprobability distribution functions become negative in some ...
1 vote
100 views

### An equation for Wigner's quasi-probability distribution?

I learned that Moyal's evolution equation is the equation for the time-evolution of Wigner's quasi-probability distribution. However, I couldn't say I perfectly understand the meaning of this ...
1 vote
91 views

### Non-uniqueness of Glauber-Sudarshan $P$-function

For a state $\rho$ acting on single bosonic mode with coherent states $|\alpha\rangle$, one can always define a $P$-function to furnish a diagonal representation of the state in the coherent-state ...
1 vote
309 views

40 views

2k views

### Understanding the relationship between Phase Space Distributions (Wigner vs Glauber-Sudarshan P vs Husimi Q)

I am moving into a new field and after thorough literature research need help appreciating what is out there. In the continuos variable formulation of optical state space. (Quantum mechanical/Optical) ...
### What is the physical interpretation of the density matrix in a double continuous basis $|\alpha\rangle$, $|\beta\rangle$?
(a) Any textbook gives the interpretation of the density matrix in a single continuous basis $|\alpha\rangle$: The diagonal elements \$\rho(\alpha, \alpha) = \langle \alpha |\hat{\rho}| \alpha \...