Questions tagged [quantum-optics]

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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How does chiral symmetry protect modes in optics?

I am reading a paper on the use of SUSY to create a robust lasing mode in optical cavities. In this paper, SUSY is used to create a super-hamiltonian of the form: $$ Q = \left ( \begin{matrix} 0 &...
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Phenomenology of photon pair production in non linear crystals

Could anyone describe the mechanism that produces photon pairs when a beam of light incides on a non linear crystal? I'm aware of the conservation arguments than can be made with the two produced ...
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Lensing effects from electric charge in electron microscopy

Are there any lensing effects from the electric charge in electron microscopy? For example, positive charge acting as a divergent lens or negative charge a convergent lens?
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Signal and idler in a twin beam state

I've seen that in quantum optics a normalized twin beam (TB) state is of the form $\left|TB\right>=\sqrt{1-|\gamma|^2}\sum_n\gamma^n\left|n\right>_S\left|n\right>_I$, where subscript S is for ...
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What is the origin of optical force?

In photoelectric effect a photon transfers its energy to an electron. Thus it does some work on an electron and work is always done via some force which in this case called optical force. I want to ...
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How to make laser written waveguides?

I don't know if this is the right place to make such a question, but I have spent a few days trying to get a review or really informative article on how to make Photonic Integrated Circuits by laser ...
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Countable basis of coherent states used to express coherent states

Let $|\alpha \rangle$ be coherent state in Fock space. According to the paper "Coherent-state representation for the photon density operator" by Cahill (Phys. Rev. 138, B1566 (1965), §VII), every ...
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Heterodyne detector

In which sense an heterodyne detector does not measure an observable? I mean, its POVM is proportional to the projector on coherent states, and the coherent states are an overcomplete set for the ...
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Relation between the Glauber correlation functions and statistical correlation

As stated in Wikipedia's page: Correlation or dependence is any statistical relationship, whether causal or not, between two random variables. Now in "The Quantum Theory of Optical Coherence" ...
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$P$ representation of a general Gaussian state

Let $\rho$ be the density operator of a Gaussian quantum state on $M$ modes. This implies that its Wigner function can be written as $$ W_{\text{Gaussian}}\left(\boldsymbol{q},\boldsymbol{p}\right)=\...
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Input-output theory: interpretation of the final expression

I am trying to understand this paper- https://journals.aps.org/pra/abstract/10.1103/PhysRevA.30.1386 I will try to give my understanding of the paper first. We start with the quantum Langevin ...
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83 views

Is the vacuum state different after a Bogoliubov transformation of phase space operators?

I am looking at the problem in the context of quantum optics. Consider this logic: In the Schrodinger picture, the state evolves in time. The time evolution of a state is given by a unitary that is ...
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Can this setup produce a no interference pattern from entangled photons from a BBO crystal?

Related question from physics exchange where the pictures were taken: From the delayed choice eraser paper from Kim et al. 1999 My question is probably quite simple. I want to know if changing the ...
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What is the difference between microwave photon and optical photon? [closed]

I am new to the field of quantum optics. Recently, I came across the term microwave photon to optical photon conversion. Does it just mean that the frequency of the light will be modulated?
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Quick way of showing visibility of HOM interference for weak coherent states?

It's shown in this paper how weak coherent states, can at-most have a visibility (using the "special visibility" of HOM interference) of 1/2 (as compared to single photons which have a visibility of 1)...
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Continuous limit for quantized E.M field in free space obtained from periodic boundary condition. I don't get it

In "The quantum theory of light" from Loudon as in many other books of quantum optic, the approach to have quantization of the free (not in a cavity) electromagnetic field is the following. We start ...
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Mean photon number from the Characteristic function of Coherent state?

While calculating the mean photon number of coherent state from the general formalism for Gaussian states, I come across the following, $<a^\dagger a>$=$(-1)\partial_{\lambda} \partial_{\lambda*...
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2 photon state split by a beam-splitter (Issue with normalization)

I'm having a simple issue in a calculation involving splitting a $|2\rangle$ state with a beamsplitter: How exactly do you calculate the probabilities of splitting a $|2\rangle$ state on a beam-...
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From photon flux to number of photons inside a cavity

Consider a light beam with photon flux $\Phi$ entering a cavity. The latter consists of two mirrors, from which photons can enter/exit at rates $\kappa_1$, $\kappa_2$, respectively. How do I obtain ...
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Phase space formulation: “Representation” vs “function” vs “quasi-probability distribution”

In the phase space formulation, the terms "representation", "function, and "quasi-probability distribution" (as in Glauber–Sudarshan P representation, $P$-function) seem to be used interchangeably. I ...
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Best topics in Quantum Information and Quantum Optics to research during PhD [closed]

I am searching for good (hot) topic in Quantum Inforamation and Quantum Optics for PhD research. I need suggestion that which direction i should go that later have good scope (good for publishing ...
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Post measurement state after heterodyne measurement

I want to understand the phase space formulation of quantum mechanics better. Specifically, I am considering the following situation: A quantum state $\rho$ on two modes can be described by its ...
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Photon antibunching Statistics

Suppose you have a single emitter with a given decay lifetime. After absorbing a photon, this emitter cannot absorb another photon. So, the probability of detecting two photons in a time interval of ...
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How does the energy of a single photon manifest itself as the frequency of the classical EM wave?

We know that the energy of the photon is given by $\hbar\omega$ and it so happens that this exact $\omega$ is the frequency we would obtain from the many photon EM wave. How does one relate the two? ...
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How can one create squeezed states by using a standing-wave?

How and why can one create a squeezed coherent state by interference with a standing-wave ? What would be the setup ?
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Cavity coupled with squeezed reservoir

So we are given the following master equation; $$\dfrac{d\rho}{dt}=-\gamma M(2a^\dagger\rho a^\dagger-(a^\dagger)^2\rho-\rho(a^\dagger)^2)-\gamma M^*(2a\rho a-a^2\rho-\rho a^2)$$ which describes a ...
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How to deduce the equation 6.2.34 in Quantum Optics (M. S .Zubairy)

In the textbook ( Quantum Optics ) for M.S.Zubairy In section 6.2 while deriving the Heisenberg operators. He assumed the equations 6.2.31 and 6.2.32 So 1- what is these equations (why it take that ...
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Coherent state and planewave: energy finite in the first but not in the second

Coherent state are supposed to represent Fourier modes of classical states of light. In free space : plane waves, in cavity : stationnary waves. Classically, a plane wave has an infinite energy. ...
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How can hydrogen spectrum be monomode (focusing on the lowest emission band)?

Consider you have an hydrogen atom. This atom can emit light under spontaneous emission for example, but the light it will emit will only be at some very specific frequencies: https://en.wikipedia.org/...
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How can energy be conserved in photon absorption at a detector?

This question is somewhat of an elaboration on the discussion here, which didn't really get a satisfactory answer. A related (but not identical) question of mine is found here, which also was not ...
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Exponential decay via spontaneous emission

Why does the exponential decay of the excited population of a two-level system (diagonal element $\rho_{ee}$ of the density matrix) into $\rho_{gg}$ (population of the ground state $\left|g\right>$)...
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Does a photon attract or repel matter?

So, I know experimentally that matter and light interact. And I can calculate cross sections in Quantum Electrodynamics. Yet a fundamental intuition about how light and matter interact is completely ...
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Phase shifting operator [closed]

https://en.wikipedia.org/wiki/Optical_phase_space#Phase-shifting_operator operator of phase shift is defined as $$U(\theta)=e^{-i\theta N}$$ where N is number operator. How to prove that $$A=U^*(\...
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Numerical simulation for spontaneous parametric down conversion

I want to numerically simulate the SPDC (spontaneous parametric down conversion) process. I have a basic background on nonlinear and quantum optics — I am a graduate student and just took a few ...
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Some good reference to study for first time the Tavis-Cummings model?

I want to study for the first time the Tavis-Cummings model. Is there some good introductory reference (article, paper, book or whatever) to learn the formalism of the model?
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Full second quantization description of the polarizing beam splitter

A very similar question has been asked here in the attempt to construct an operator that describes PBS as it acts on single-photon states in the modes of a system. The answer to this question aims at ...
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Is there any introductory reference for the study for first time the Jaynes-Cummings model?

Is there any good reference (notes, paper, book, etc) for study step by step and for the first time the Jaynes-Cummings model? Specially I am looking for a good reference that keep insight the ...
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Difference between multiphoton signal and, $n$-photon signal state

I was reading decoy state quantum key distribution article, by Lo et.al. (PRL paper , PRA paper). In this article, authors have discussed the possibility of photon number splitting attack due to ...
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Difference of squeezed state in closed or opened system

Is there any difference between the wave and wigner functions of squezeed state of light in a closed system and in a opened system?
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Squeezed state expectation value form

What is the form of $$S^+px^2S$$? (where $S$ is the squeeze operator.) I know the form of $S^+pS$ and $S^+x^2S$ but no matter how I calculate it I cant find the form for $S^+px^2S$. The main problem ...
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Squeezed state of light

I was searching for the wigner function for the squeezed state, but I'm not finding it. So, what is the wigner function for it?
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Can we diagonalize optomechanical hamiltonian?

The optomechanical hamiltonian is given as $$\hat{H}=\hbar\Delta_{a}a^{\dagger}a+\hbar\omega_{m}b^{\dagger}b+\hbar g_{a}a^{\dagger}a(b^{\dagger}+b)$$ $a$ and $b$ are photonic and phononic operators ...
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What will happen with the reflected energy wave when we connect the mirror under voltage?

What will happen with the reflected energy wave when we connect the mirror under voltage and we will manipulate voltage level? The frequency of the reflected wave will change? Amplitude of the ...
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What should be the scattering matrix to transparent device?

The scattering matrix for a 2 port diode is given as $$S=\begin{pmatrix} 0 & 0 \\ 1 & 0 \\ \end{pmatrix}$$ Suppose I want to make this device transparent, that any mode just passes through ...
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What is QED about “Cavity QED”?

As I understand it, when papers and books refer to "Cavity QED" they simply mean the strong coupling regime of two-level system to a photon field in a resonator, i.e. Jaynes-Cummings and variants ...
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Thermal Population of a Quantum State with Tunable Frequency

I've been working on understanding tunable LCJJ oscillators (an example paper on such a thing can be found here: https://arxiv.org/abs/0712.0221) and I was wondering if anyone had any input on the ...
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Where does the photon orbital angular momentum go in light-matter interactions?

Just as a photon's polarization determines its spin angular momentum (or more accurately its helicity), its wavefront can carry orbital angular momentum (OAM) much like an electron in an atom. ...
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Can we create “asymmetric” EPR pairs in experiments?

Asymmetric here is just for lack of a better word. What I am looking for are experiments that can create a simple EPR pair but without 50% 50% chance of each state. As I understand from standard ...
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Interference of single photons emitted from solid state sources

Solid state emitters such as quantum dots are thought of as being amongst the best single photon sources for quantum technology. There have been impressive demonstrations of >10 photon experiments ...
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What is the difference between classical nonlinear optics and multiphoton physics?

Nonlinear optics is usually looked at through a classical lens for most purposes. I do a Taylor expansion of the material polarization in terms of light-field strengths and we can derive all the ...

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