Accueil du site > Atomes, cavités et photons > Principes de l’electrodynamique quantique en cavité
Principes de l’electrodynamique quantique en cavité
Un oscillateur : mode de la cavité
The single cavity mode is a quantum harmonic oscillator. We recall here its main properties and those of quantum states of interest, Fock and coherent states.
In these sections, we provide only a short presentation. More information can be found in
Fock states
A single field mode is equivalent to a one-dimensional harmonic oscillator. The non-degenerate energy eigenstates are the Fock or `photon number states’ $\ ; n\rangle\ n>0$, whose energy is $\hbar\omega_c (n+1/2)$, where $\omeaga_c$ (...)
Relaxation du champ
The main relaxation channel is the cavity damping. We show here how it can be incorporated in the theoretical description of the experiment, in the master equation framework or using quantum Monte Carlo trajectories.
Master equation
Decoherence is the result of a dissemination of information about a system via its entanglement with an environment $E$. For all practical purposes, this information is buried in $E$ on which no measurement can be performed in practice. The system density (...)
Le spin : un atome à deux niveaux
The two level atom is equivalent to a spin 1/2 system. We recall here its main properties.
A spin system and the Bloch sphere
A two-state system can be described without loss of generality, as a `pseudo-spin’ $S$. This analogy will lead us to a geometrical representation of the system, widely used in NMR physics, which will prove very useful. The component of this spin along an arbitrary direction in three-dimensional space can take only one of the two values $\pm\hbar/2$. The most general (...)
Spin et oscillateur : états habillés
The coupled atom-field system is conveniently described in terms of the dressed states. We use them to investigate the quantum Rabi oscillation at resonance and the dispersive shifts in the non-resonant case.
The Jaynes-Cummings hamiltonian
The complete atom-cavity hamiltonian writes : $$ H=H_a+H’_c+H_ac\ , $$ where $H_a$ and $H’_c$ are the atom and cavity hamiltonians. The coupling term, $H_ac$, is $-D\cdot E_c$, where $E_c$ the electric field operator at the atomic location. The (...)
