Questions tagged [coherent-states]
The specific quantum state of the quantum harmonic oscillator, often described as a state which has dynamics most closely resembling the oscillatory behavior of a classical harmonic oscillator. It obeys the minimal uncertainty relation in Heisenberg's uncertainty relationship.
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SPDC One Arm vs Very Weak Coherent state
I know that SPDC(Spontaneous Parametric Down Conversion) is a method to generate heralded single photon source.
So If we do homodyne tomography of single photon fock state, another arm of SPDC is used ...
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Quantum Harmonic Oscillator density matrix in coherent states base [closed]
I was trying to calculate matrix elements of the density operator for a 1D QHO (with Hamiltonian $\mathcal H = \hbar\omega a^\dagger a $) in the base of coherent states $\{\vert\alpha\rangle\}$ and ...
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Normal ordering of an exponential [duplicate]
I would like to recalculate Eq.(2.4) in PRA, 31,4,(1985), which expresses the exponential of operators as a normal ordering form. This equation reads
\begin{equation}
D=e^{\alpha K_{+} - \alpha^{*} K_{...
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Decomposing a coherent state? [closed]
Can you decompose a coherent state $|\alpha\rangle$ into $p|p\rangle+q|q\rangle$, where $|p\rangle$ and $|q\rangle$ are eigenstates of the $P$ and $Q$ operators respectively with eigenvalues p and q?
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Confusion with two-mode bra-ket notation [closed]
Let us consider some abstract two-mode bosonic model with a conserved total number of quanta (i.e. eigenvalue $N$ of the operator $\hat{N} = a^\dagger a + b^\dagger b$ remains constant with ...
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Heisenberg picture and time dependence of a wave function
I'll try to give you a quick background of what I'm doing, then the question will come: I'm studying an EFT where a coherent state of a scalar field $\Phi$ reproduces a static potential $V(r)$ through ...
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How is continuous variable quantum key distribution safe against tapping some photons?
As far as I understand, CV-QKD (also here) uses coherent states to send a key, that is encoded in amplitude and phase quadratures. When someone tries to eavesdrop, this will introduce an error and ...
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Equation of motion for space and momentum of a $\textbf{coherent state}$ [closed]
Given the coherent states
$$| \alpha \rangle\, e^{\textstyle -|\alpha|^2/2}\,\sum_{n = 0}^\infty \dfrac{\alpha^n}{\sqrt{n!}}\,|n\rangle$$
that satisfy the eigenvalue-equation: $A|\alpha\rangle=\alpha\,...
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Master equation with a coherent bath
When we consider an oscillator $a$ acting with a bath of oscillators $b_i$ with the interaction Hamiltonian reads
$$H_{int}=\sum_{i}g_ia b_i^{\dagger}+g_i^*a^{\dagger}b_i,$$ with the free Hamiltonian:
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Fock Space and Coherent state
Can a coherent photon state also belong to the Fock space? If yes, under what conditions? For example I read that
$$\exp\bigg\{-\frac{1}{2}\sum_i|\alpha_i|^2\bigg\}\exp\bigg\{-\sum_i\alpha_ia_i^{\...
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Is it possible to define the operator similar to the Displacement $|\alpha\rangle = \hat D|0\rangle$ but from the coherent state to the Fock space?
I am looking for the theory of electro-optical modulator with Fock states as an input and I know how the modulator acts on the coherent states. Knowing the connection between coherent and Fock states. ...
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Number and phase operators in superconductors
It is stated in many texts that the number operator $N$ which counts the number of Cooper pairs and the phase operator $\phi$ which counts the superconducting order parameter's phase $\text{Arg}(\...
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Number-Phase uncertainty relation
I was trying to understand the Number-Phase uncertainty mainly following "A. Duncan, The Conceptual Framework of QFT", pages 223-233 and I got stuck into the definition of the operator
$$E = ...
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If I split coherent state light in half (by a beam splitter) are the 2 output intensities correlated?
From what I have been told and understand, if I use a simple beamsplitter to split coherent state light, I will obtain 2 coherent states as a result.
Are the intensities of these two output states ...
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References on coherent states
I've begun my Master degree final work and I was asked to study in details coherent states. The goal is to apply them to a QFT formalism for a scalar potential effectively decribing the weak field ...