arXiv subjects

Martti Havukainen

Publications and source records attributed to Martti Havukainen.

3 recordsLinked to original sources

arXiv1999

Comparisons of spectra determined using detector atoms and spatial correlation functions

We show how two level atoms can be used to determine the local time dependent spectrum. The method is applied to a one dimensional cavity. The spectrum obtained is compared with the mode spectrum determined using spatially filtered second order correlation functions. The spectra obtained using two level atoms give identical results with the mode spectrum. One benefit of the method is that only one time averages are needed. It is also more closely related to a realistic measurement scheme than any other definition of a time dependent spectrum.

quant-ph↗

arXiv1998

Coherence properties of the stochastic oscillator

An oscillator with stochastic frequency is discussed as a model for evaluating the quantum coherence properties of a physical system. It is found that the choice of jump statistics has to be considered with care if unphysical consequences are to be avoided. We investigate one such model, evaluate the damping it causes, the decoherence rate and the correlations it results in and the properties of the state for asymptotically long times. Also the choice of initial state is discussed and its effect on the time evolution of the correlations.

quant-ph↗

arXiv1997

An open systems approach to calculating time dependent spectra

A new method to calculate the spectrum using cascaded open systems and master equations is presented. The method uses two state analyzer atoms which are coupled to the system of interest, whose spectrum of radiation is read from the excitation of these analyzer atoms. The ordinary definitions of a spectrum uses two-time averages and Fourier-transforms. The present method uses only one-time averages. The method can be used to calculate time dependent as well as stationary spectra.

quant-ph↗