arXiv subjects

A. Porzio

Publications and source records attributed to A. Porzio.

23 records · Page 2Linked to original sources

arXiv2005

Optical response of a misaligned and suspended Fabry-Perot cavity

The response to a probe laser beam of a suspended, misaligned and detuned optical cavity is examined. A five degree of freedom model of the fluctuations of the longitudinal and transverse mirror coordinates is presented. Classical and quantum mechanical effects of radiation pressure are studied with the help of the optical stiffness coefficients and the signals provided by an FM sideband technique and a quadrant detector, for generic values of the product $\varpi τ$ of the fluctuation frequency times the cavity round trip. A simplified version is presented for the case of small misalignments. Mechanical stability, mirror position entanglement and ponderomotive squeezing are accommodated in this model. Numerical plots refer to cavities under test at the so-called Pisa LF facility.

quant-ph↗

arXiv2003

Trapped ions interacting with laser fields: a perturbative analysis without rotating wave approximation

The Hamiltonian describing a single ion placed in a potential trap in interaction with a laser beam is studied by means of a suitable perturbative approach. It is shown, in particular, that the rotating wave approximation does not provide the correct expression, at the first perturbative order, of the evolution operator of the system.

quant-ph↗

arXiv2002

Evolution of the N ion Jaynes-Cummings model beyond the standard rotating wave approximation

A unitary transformation of the N-ion Jaynes-Cummings hamiltonian is proposed. It is shown that any approximate expression of the evolution operator associated with the transformed hamiltonian retains its validity independently from the intensity of the external driving field. In particular, using the rotating wave approximation, one obtains a solution for the N-ion Jaynes-Cummings model which improves the standard rotating wave approximation solution.

quant-ph↗

arXiv2002

Resonances and spectral properties of detuned OPO pumped by fluctuating sources

Twin beam fluctuations are analyzed for detuned and mismatched OPO configurations. Resonances and frequency responses to the quantum noise sources (quantum and pump amplitude/phase fluctuations) are examined as functions of cavity decay rates, excitation parameter and detuning. The dependence of self- and mutual correlations of beam amplitudes and phases on detuning, mismatch and damping parameters is discussed.

quant-ph↗

arXiv2000

Trapped ions in laser fields: A benchmark for deformed quantum oscillators

Some properties of the non--linear coherent states (NCS), recognized by Vogel and de Matos Filho as dark states of a trapped ion, are extended to NCS on a circle, for which the Wigner functions are presented. These states are obtained by applying a suitable displacement operator $D_{h}(α) $ to the vacuum state. The unity resolutions in terms of the projectors $| α, h> < α, h^{-1}| ,| α, h^{-1}> < α, h| $ are presented together with a measure allowing a resolution in terms of $| α, h> < α, h| $. $D_{h}(α) $ is also used for introducing the probability distribution funtion $ρ_{A,h}(z) $ while the existence of a measure is exploited for extending the P-representation to these states. The weight of the n-th Fock state of the NCS relative to a trapped ion with Lamb-Dicke parameter $η,$ oscillates so wildly as $n$ grows up to infinity that the normalized NCS fill the open circle $η^{-1}$ in the complex $α$-plane. In addition this prevents the existence of a measure including normalizable states only. This difficulty is overcome by introducing a family of deformations which are rational functions of n, each of them admitting a measure. By increasing the degree of these rational approximations the deformation of a trapped ion can be approximated with any degree of accuracy and the formalism of the P-representation can be applied.

quant-ph↗