A research field within general optical physics concerned with light and its material interaction: where light is modelled by full quantum mechanical description.

learn more… | top users | synonyms

-2
votes
2answers
59 views

How do Rabi oscillations act on the relative phase of state kets

Suppose we have a system with a lower state $\left|{\downarrow}\right\rangle$ and and upper state $\left|{\uparrow}\right\rangle$, coupled by a pulsed electromagnetic field. I thought that from an ...
2
votes
1answer
55 views

Relationship between position and momentum matrix elements

I am going through Faist's Quantum Cascade Lasers book. In the first section of the fourth chapter, he asserts that (in the context of a perturbative analysis of electronic transitions) the ...
0
votes
2answers
69 views

Completeness relation for coherent states of the quantum harmonic oscillator

For the Quantum harmonic oscillator with energy eigenstates $|n\rangle$ one defines a coherent state for every complex number $z$ by setting (note that the normalization varies across the literature) $...
3
votes
2answers
226 views

Quadrature in quantum optics

I am reading a chapter about Squeezed state, and came across this word, quadrature, which I have never seen before in the book. Here is the quote from that chapter. " A general class of minumum-...
3
votes
1answer
74 views

What is the physical meaning of the parameter of a Poisson distribution?

I have done a laboratory session at my university where I had to check that the disintegration of nucleii follows a Poisson distribution $$P(n)=\frac{\lambda^n}{n!} e^{-\lambda},$$ where $P(n)$ is ...
1
vote
0answers
44 views

What is an “antiquated” coherent state?

I am studying entangled coherent states. Some of the papers I looked up (for example http://www.global-sci.org/jams/open-access/v2n2/pdf/022-155.pdf) mention some special properties of entangled ...
1
vote
1answer
20 views

Dipole interaction for a two-level system in a trap potential

Consider a two-level system under the following Hamiltonian: $H=H_{I}+H_{E}+H_{dip}$ where $H_I$ is the Hamiltonian for the two internal states of the two-level system $span \{\left |e \right> {,}...
0
votes
1answer
18 views

Inverting squeezing and displacement operators

This question is about inverting the product of squeezing operator and a displacement operator in the following way: I have $D(\alpha)S(\xi)$ and I'd like to turn it into $S(\xi')D(\alpha')$. Where $...
2
votes
0answers
43 views

Intuition for why there are quantum beats in $V$-type but not in $\Lambda$-type atoms

When calculating the emitted intensity of an excited $\Lambda$-type or $V$-type atom with a quantized field (instead of a semiclassical approach with only quantized energy levels) one finds that there ...
0
votes
1answer
41 views

How to understand the electric-field operator in quantum optics?

I know the positive field operator $\mathbf{E}^{+}$ is actually an annihilation operator $a$ while the negative field $\mathbf{E}^{-}$ is a creation operator $a^{+}$. I also learned that the ...
0
votes
2answers
34 views

Book Recommendation: Quantum optics

Could you suggest me a list of books for understanding Quantum Optics for students who have studied Introductory Q.M. (such as Griffiths). It would be grateful if you distinguish between readable one ...
3
votes
2answers
265 views

Can spatial coherence be maintained in fiber optic cables over time?

I am doing research with a double slit experiment, using a beam splitter and 2 lengths of fiber optic cable, whose ends brought close together form the effective double slit. I notice that the ...
14
votes
7answers
1k views

Are coherent states of light 'classical' or 'quantum'?

Coherent states of light, defined as $$|\alpha\rangle=e^{-\frac{|\alpha|^2}{2}}\sum_{n=0}^\infty \frac{\alpha^n}{\sqrt{n!}}|n\rangle $$ for a given complex number $\alpha$ and where $|n\rangle$ is a ...
2
votes
1answer
277 views

First order coherence through double slit

The state $$|\Psi \rangle = |0\rangle + \sum_j \int d\omega f_j(\omega)\hat{a}^\dagger_j (\omega) |0\rangle $$ is coming from a far field and incident on a double slit setup. Here j is the index of j-...
4
votes
1answer
89 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)...
1
vote
1answer
32 views

Is 3D optical lattice just a stack of 2D lattices?

I am confused about the idea of 3D optical lattice. Many papers use 3D optical lattice to study bosons behavior, but is it really a 3D system where atoms interact in all three directions or is it just ...
0
votes
0answers
15 views

Can DC electric field be regarded as a quantum harmonic oscillator? [duplicate]

The essence of quantum theory of the radiation field is the association of a quantum harmonic oscillator with each mode of the field. However, in the case of DC electric field, can we describe DC ...
-1
votes
1answer
38 views

Wigner Function for Thermal State

I am currently doing a reading on the subject of Quantum Optics from the book "Quantum Optics by Marlan O.Scully and M.Suhail Zubairy", I am currently learning about Quasi Probability distributions. ...
0
votes
1answer
32 views

Energy loss of photons crossing a dielectric medium

How much energy do photons lose when crossing an "isotropic" dielectric medium? What would be possible mechanisms. I assume the straight forward answer would be that the photon loses zero energy and ...
4
votes
2answers
508 views

double slit experiment with two opposite quarter waveplates

Consider the usual double slit experiment involving laser and a double slit and a screen. Now place in front of the left slit a quarter waveplate (let's call it QWP1) that changes a certain linear ...
-3
votes
1answer
53 views

Gravitational Lensing Example

Like this tomato wrapped underwater and how light is bent around it does the way a black whole bends space and light in the same way?
0
votes
0answers
48 views

What does phase shift represent in a Mach-Zehnder interferometer?

When describing the polarization of a photon, phase refers to the difference in the phases of the polarization components. E.g.: $|\psi\rangle$ = $|L\rangle$ + $i|R\rangle$ can be said to have a ...
3
votes
2answers
87 views

Meaning of non-degenerate photon pair

I am seeing in a lot of papers about quantum optics the term "non-degenerate photon pair", which seems like a very important concept. This may seem like a silly question, but I am an EE undergrad who ...
1
vote
1answer
27 views

What do the authors mean by “closing operator”?

I'm reading a paper titled "Luminescence spectra of quantum dots in microcavities II Fermions" (link). In section III, the authors introduce so-called closing operators. I don't have enough background ...
0
votes
1answer
614 views

Formula for Rabi frequency

The Rabi frequency is an expression of the light-matter interaction (Hamiltonian) and gives a relation between field polarization and electric dipole. Reading the book of Cohen-Tannoudji (Complement $...
6
votes
1answer
134 views

Von Neumann entropy of mixtures of coherent states

I'm trying to calculate the Von Neumann entropy of statistical mixtures of coherent states. The problem is that such states are in general non-Gaussian, so one cannot follow the formalism developed ...
1
vote
1answer
40 views

How to find the covariance matrix after a partial homodyne measurement?

The Gaussian state of two modes, with quadrature operators $X_1,P_1,X_2,P_2$, is given by a displacement vector $d$ and covariance matrix $\sigma = \begin{bmatrix} Var(X_1,X1) & Var(X_1,P_1) &...
14
votes
2answers
1k views

Photons with half integer angular momentum - what's happening?

I have just read this article - what is happening? Analysing these beams within the theory of quantum mechanics they predicted that the angular momentum of the photon would be half-integer, and ...
1
vote
1answer
3k views

Explanation of the experiment with Mach–Zehnder interferometer (self-interference of a single photon)

Here is the description of experiment which uses Mach–Zehnder interferometer http://en.wikipedia.org/wiki/Mach%E2%80%93Zehnder_interferometer or http://departments.colgate.edu/physics/research/...
0
votes
0answers
25 views

How can I calculate the time domain correlation function in the frequency domain?

I have an operator $a(t)$, its correlation function is: $$<a(t)a^{\dagger}(t^{\prime})>=\delta(t-t^{\prime})$$ Now I need to find the correlation function in the frequency domain. i.e. to ...
0
votes
0answers
28 views

Bandwidth of second-harmonic generated (SHG) field for pulse excitation

I wanted to know the bandwidth of the second-harmonic field generated from type-I SHG process when excited with a pulse of bandwidth $\Gamma$. In this lecture notes, the author calculates the ...
0
votes
0answers
52 views

Physical Significance of Wigner Equation, Wigner Current

I am Currently doing a reading about Wigner function in Quantum optics, I learnt that the Wigner function maps the Quantum mechanical operators to phase space functions in phase space, so we can talk ...
0
votes
1answer
31 views

Parity conservation in second harmonic generation?

The second harmonic arises from susceptibility of third rank tensor $X^{(2)}$ which have (-1) parity. page 28 Let say two photons are absorbed and one is emitted, so the total change in parity is $(...
0
votes
1answer
53 views

Gaining some intuition: Photon bunching

This is a very easy question: I'm in need of some intuition on the fact that, e.g. thermal sources, produce bunched photons. It is very easy to "undertand", without any quantum mechanics, why single ...
2
votes
1answer
47 views

Is Mott insulator the same as non-compressible quantum fluid?

In the field of ultracold quantum gases we study the so called Bose-Hubbard model given in second quantization: $$\hat{\mathcal{H}} = -t\sum_{\langle i,j\rangle}\hat{a}^{\dagger}_{i}\hat{a}_{j} + \...
3
votes
1answer
31 views

Reaching equilibrium in a blackbody and light-matter interaction

Suppose we have a metallic cavity maintained at a fixed temperature. Suppose we start with any distribution of radiation that is not in equilibrium with the container. Gradually, when the equilibrium ...
0
votes
1answer
56 views

Rotating wave approximation for two coupled resonators and a drive

I'm having some trouble with what I think should be an easy calculation. On qutip.org/docs/2.2.0/examples/me/ex-25.html they calculate the steady state for a master equation, more specifically they ...
0
votes
0answers
22 views

How is the conversion from an operator equation to a c-number stocastic differential equation justified?

In many papers on laser dynamics theory, quantum Langevin equation of operators is converted to c-number stocastic differential equations, which is analyzed to obtain results. However, why this ...
3
votes
1answer
42 views

Difference between Amplitude and Intensity Interferometer?

A lot of books explain the first order and second order coherence correlations for light. They explain the difference between these using interferometers (Michelson and Hanbury-Brown and Twiss (HBT) ...
0
votes
1answer
46 views

Sech laser pulse time-bandwidth product calculation

Find the time bandwidth product for a $\operatorname{sech}$ shaped pulse. Attempt: I know that the time bandwidth product $\Delta t \Delta \omega$ for a $\operatorname{sech}$ shaped pulse must be $...
0
votes
1answer
66 views

Why probability of detection by performing unambiguous quantum measurement is less than random guess in mesoscopic quantum regime?

In mesoscopic quantum regime (mean photon number 10000) and non-orthogonal coherent state(number of non-orthogonal coherent state 2000), why probability of detection by performing quantum unambiguous ...
0
votes
0answers
14 views

Why probability of detection of optimum unambiguous discrimination between linearly independent symmetric states is less than random guess? [duplicate]

Considering the analysis and result of this paper, http://arxiv.org/pdf/quant-ph/9807023v1.pdf, I have used equation (3.15) and (4.3) to calculate the optimum probability of success for mean photon ...
8
votes
1answer
253 views

In quantum optics if you measure the energy of a thermal state does it collapse to a Fock state (Photon number state)?

As I understand it a thermal state is a state of light such that the light is in a superposition of many Fock states (Photon number states) with the probability of the light being found in a ...
0
votes
1answer
82 views

Representing operators in the Glauber-Sudarshan P-representation

If $| \alpha >$ represents a coherent state (the normalized right eigenstate of the destruction operator $a$ in Quantum Mechanics; $\alpha$ is a complex number), then it is known that: \begin{...
12
votes
3answers
2k views

What causes atoms to have their specific colors?

I understand that light (color) is part of the electromagnetic spectrum, and that it depends on what wavelengths are reflected/absorbed. Though what property of an individual atom gives it its color? ...
2
votes
0answers
50 views

Second Order Coherence of NOON State

Given the entangled state $\vert NOON \rangle =\frac{1}{\sqrt{2}}(\vert N,0\rangle + \vert 0,N\rangle)$ how can the second order coherence function at time $\tau$ and 0 be calculated? I know that $g^{...
3
votes
1answer
37 views

Master equation approach only suitable for good cavity laser?

As I understand, master equation and quantum Langevin equation are equivalent formalisms. However, in a Review of Modern Physics article titled sub-Poissonian processes in quantum optics, the author ...
0
votes
0answers
18 views

Resonance Fluorescence spectrum of a symmetric state of two atoms

So recently I've learned about the fluorescence spectrum of an atom (say a two level system) driven by a laser close to its resonance frequency. You get a dressing of the atom states with the laser, ...
3
votes
1answer
90 views

What exactly happens when total internal reflection takes place at a quantum level?

What happens when light interacts with the boundary between 2 mediums at a quantum level? Why is it totally reflected back when it is travelling from an optically denser to a less dense medium? How ...
2
votes
1answer
63 views

How to transform a wigner function to represent loss of mode information (coarse graining)?

I have a highly multi-mode gaussian wigner function representing an optical field: $$W\left(\{p\},\{q\}\right)=\mathrm{Exp}\left(-\sum_{j=0}^{f}(b_{j}q^{2}_{j}+a_{j}p^{2}_{j})\right).$$ However the ...