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

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damped quantum harmonic oscillator - evolution of coherent state

I am trying to solve the following Master equation (also similar to damped quantum harmonic oscillator): $$\frac{d\hat{\rho}}{dt} = \frac{\Gamma}{2}\left(2\hat{a}\hat{\rho}\hat{a}^{\dagger} - ...
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20 views

Wigner functions, symmetry

I'm trying to get more insight into quasiprobability distributions, as for example the Wigner function. There are some Wigner functions, which are symmetric. Symmetric: Fock state Thermal states ...
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38 views

Wave vector relation in nonlinear material

A light wave ($k_1,\omega_1$) travels in a medium of refractive index $n_1$ and then encounters a nonlinear medium ($n_2$) under the angle $\theta_1$. Snell's law tells us the wave's direction in the ...
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48 views

What is the reason behind total internal reflection?

I know that when we increase i , r increases unevenly, i.e i increases a little but r increases with a greater amount. At some time, when i reaches the critical angle, r becomes 90 and if we further ...
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117 views

Annihilating coherent state

Starting facts Annihilation operator $a$ removes one photon from fock state. Coherent states are eigenstates of annihilation operator and they are also superposition of different fock states. This ...
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37 views

Atomic system satisfying a simple level scheme

I have a simple two level system with an allowed dipole transition between the levels. The top level is also allowed to decay to another third level (looks a bit like a lambda system). Could someone ...
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62 views

Exact meaning of “pi/2 pulse”

In studying Mach-Zehnder and Ramsey interferometers, I came across the expression "$\pi/2$ pulse". What does it mean exactly? I am working with a Bloch vector representation $(u,v,w)$ of a 2 state ...
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32 views

Multi-photon excitation probability for a two-level system

If a two-level system with a lifetime $\tau$ is excited with a pulse of duration $t_{pulse}$, what is the probability of exciting more than one photon? For simplicity we can take it to be a $\alpha ...
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67 views

Varying the Predictability in a Double Slit Experiment

I know that the Englert-Greenberger-Yasin Duality Relation states that as the predictability of finding a photon at a slit in a double slit experiment increases, the visibility of the interference ...
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25 views

What exactly makes transmittance of graphene change from linear to exponential?

Up to 5 layers, the transmittance of graphene is linear (2.3% per layer): (source) Beyond 5 layers (I assume) the transmittance is exponential, following Beer–Lambert law. What gives rise to this ...
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7 views

Reason for the difference between Photoluminescence and RAMAN widths

I am measuring the Photoluminescence and RAMAN spectra of a few samples but am unable to understand one thing, why are the width of the photoluminescence bulges so broad while the width of the RAMAN ...
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72 views

What is a quasi-probability distribution?

I have some questions about the quasi-probability distribution. What is it? And why it is important in quantum mechanics? And what does "quasi" mean?
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54 views

What happens to the Fringe Width when the velocity of electrons passing through the slit in Young's Double Slit Experiment increases?

A beam of electron is used in Young's Double Slit Experiment. The slit width is d. Then the velocity of electron is increased. What happens to the Fringe Width? My approach: $$\beta = ...
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99 views

Transformation of Jaynes-Cummings Hamiltonian

This is the Jaynes-Cummings Hamiltonian in the interaction picture: $H_i^n = \hbar g \sqrt{n+1}\begin{pmatrix} 0 & \exp(-i\delta t)\\ \exp(i\delta t) & 0 \end{pmatrix}$ I want to transform ...
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71 views

Improper integral of the product of exponential function and Laguerre polynomial

I saw this integral in the book [Gerry C.C.,Knight P.L.] Introductory quantum optics: ...
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1answer
34 views

How the Jordan Schwinger components transform the mode operators in a Beam Splitter- component

Hello, I am unsure how to prove this equation. It is suggested to take the derivative with respect to theta on both sides and use commutation relations for the Jordan Schwinger operators. I can't ...
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38 views

Varying the Relative Amounts of Light Passing Through Each Slit in the Double Slit Experiment

What happens if different amounts of light pass through each slit in the double slit experiment? For example, if twice as much light passed through one slit as through the other slit, how would the ...
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1answer
28 views

Computing covariance matrix of two mode state?

Suppose that I want to calculate the covariance matrix of the state of modes $A$ and $C$ with quadrature $(x_a, p_a)$ and $(x_b,p_b)$ . But instead of the state in order to calculate all expectation ...
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27 views

element effect on quantum dot band gap

Main Question: Why do Au QDs have quantum confinement effects which change optical behavior from the bulk Au, whie certain other elements (such as Fe) are typically not shown to have the same ...
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37 views

Can thermal states of light be monochromatic?

As one can read from the quantum optics textbooks each mode of light of a certain frequency, spatial configuration and polarization can be considered as a quantum harmonic oscillator. One can imagine ...
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92 views

The definition of Gaussian State

Could you clarify to me what is a Gaussian state? I know what is a Gaussian function and Gaussian distribution, but I don't know how to respond to other when they ask me to provide the definition of a ...
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1answer
79 views

Diagonalizing a linearized optomechanical Hamiltonian

in the paper Nonlinear Interaction Effects in a Strongly Driven Optomechanical Cavity, the authors diagonalize the Hamiltonian (equation (2) in the paper) $$H_1=−Δd^†d+ω_Mb^†b+G(d+d^†)(b+b^†)$$ in ...
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48 views

Quantum Crypto infrastructure & hardware

To implement real quantum cryptography in the real world, does the physical link layer from Point A to Point B be an optical link for all parts? Is there any links or whitepaper containing prototypes ...
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40 views

What is the exact mechanism in line broadening of transition frequencies?

I've been having trouble understanding why transition lines in unperturbed states are not infinitely narrow. I'll run through my reasoning and hopefully that helps find the flaw. I imagine that if we ...
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29 views

How could you match the phase of two waves?

Imagine the Mach-Zehnder interferometer with split beams of a laser guided in a way that would result in constructive interference in one direction and destructive interference in the remaining ...
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1answer
46 views

Is there a beam splitter in time?

I have a train of pulses (with some known time separation between them) and I want to mix two of these (perform an XOR - beam splitter transformation - between them), leaving the rest alone. How do I ...
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104 views

Maxwell equations and quantized electromagnetic field

When the electromagnetic field is quatized for a single mode, we first take Maxwell equations and proceed to write the electric and magnetic field as a stationary wave, since we consider the ...
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32 views

How is the temporal coherence of a pulse defined?

I am having problem with the concept of coherence and photon degeneracy. The temporal coherence of pulse is defined in Born and Wolf as: $$t_c=\lambda^2/c\Delta\lambda$$ (The time a photon takes to ...
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36 views

Stimulated emission role in laser cooling

Laser cooling can be achieved by exciting an atomic system, in order to "pump" atoms in the excited state. This gives a recoil momentum $\hbar k$ the the atom, which then emits spontaneously. As ...
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29 views

Interpretation of different values of antibunching

When the frequency resolved second order correlation function at zero time delay, $$g^{(2)}(\omega_1, \omega_2) = \frac{\langle a_1^\dagger a_1(t) a_2^\dagger a_2(t)\rangle}{\langle a_1^\dagger ...
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1answer
61 views

Why does the discussion in a certain reference frame gives us the correct physics?

The question: whenever you are dealing with quantum optics you will encounter a lot of unitary transformations very soon. A question that is in my mind for quite a long time is: Why does the ...
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12 views

Is the truncated Wigner method efficiently classical simulatable?

The continuous-variable Gottesman-knill theorem says that the operation which varying the initial state described as the gaussian function (such as vacuum) to the final state described as the gaussian ...
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36 views

Are there any other tests demonstrating wave properties besides interference and diffraction?

Are there any other tests demonstrating wave properties besides interference and diffraction? How about refraction? Does it show wave properties also?
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56 views

Time multiplexed detector - pulse dispersion - foruier limits.

I'm currently in my second semester in physics and a couple of weeks ago I saw a job offer in the optics department of my university. Although I don't know much about optics, since we didn't deal with ...
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65 views

Gain clamping and threshold gain in quantum optics

We increase the pump power of a laser to the point where laser action starts, i.e. the threshold gain is reached. Now we increase the pump power even more, which increases the intensity of the cavity ...
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37 views

Is there a theoretical derivation of Kim's delayed choice quantum eraser?

Is there a theoretical derivation of Kim's delayed choice quantum eraser? The original paper only shows the experimental data.
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233 views

Are photons inside the media massive? If yes, why there is no Meissner effect?

We all know in vacuum travels with speed $c$, hence its rest mass has to be 0. In the media the light speed $v<c$. Then the photon renormalized by the medium (call it "quasi-photon" if you like), ...
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140 views

'size' of a photon

What's the smallest apperture a photon can pass through? I mean with no transmission at all. I'm pretty sure I saw long ago an experiment when they were reducing the size of a hole in a gold film and ...
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1answer
64 views

What is the different between a dark state and a ground state?

In a atomic quantum system, typically discussing in quantum optics, there is something called dark state. A dark state is a state of a quantum system that does not emit any photon. A ground state also ...
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26 views

In Rayleigh's criterion, why does length not figure in the minimum achievable resolution?

For an $n$ slitted grating, Rayleigh's criterion is given by: $\frac{\Delta \lambda}{\lambda} = \frac{1}{Nm}$ (*) When I imagine two lightwaves of slightly different wavelength being shown through ...
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25 views

Are the produced entangled photons in type II SPDC always in phase?

Are the produced entangled photons in type II SPDC (spontaneous parametric down conversion) always in phase? In Kim's delayed choice quantum eraser, two entangled photons are produced by a BBQ ...
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27 views

Is the master equation appropriate for a single system?

The master equation (Lindblad equation) describes the evolution of the density matrix of a system. Since it is a density matrix, so inherently, it describes an ensemble instead of a single system? In ...
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51 views

Light (Laser) operated optical switch

I have searched the web and found that optical switches are activated either through mechanical or electro/magnetics. Making them sort of Optomechanical or optoelectronic switches. Lets exclude ...
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1answer
645 views

Obtain the Lagrangian from the system of coupled equation [closed]

In this particular paper, "Interaction between a moving mirror and radiation pressure: A Hamiltonian formulation" by C.K.Law, PhysRevA.51.2537 \begin{equation} ...
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101 views

Thought experiment on light accumulation

Consider an object which is a spherical one-way mirror, and let's call it the "Sphere". For the needs of the thought experiment, suppose that: the Sphere is perfectly spherical the mirror is ...
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Ramsey pulse versus optical pumping: what's the difference?

A Ramsey pulse is a coherent process, where the electronic states of for example an ion (or some other two-level-system) are coupled to a laser field. By tuning the laser precisely, we can coherently ...
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49 views

What degrees of freedom (other than polarization) of a photon can be used to store quantum information? [duplicate]

Usually in quantum optics, one uses the polarization degree of freedom of the photon to create and manipulate photonic qubits. This, using various linear optics devices, can be coupled with the 'path ...
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35 views

The Longest Storage Time of Electromagnetically-Induced-Transparency-Based Quantum Memory

Do anyone know any paper that demonstrate the longest storage time of quantum memories protocol based on EIT achieved experimentally? I have tried to look for it on Google but find nothing.
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94 views

How to Derive Atomic Hamiltonian and Cavity Hamiltonian?

In a Fundamental of Quantum Optics and Quantum Information book which I am reading, it states without explanation that, in a two-level atomic configuration in a cavity system, the Atomic ...
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correlation function of coherent states

Hey folks, I got a question regarding the correlation function of coherent states. Which of the following states are n-degree coherent, i.e all g_n are equal to one. The first one is something ...