arXiv subjects

Victor V. Dodonov

Publications and source records attributed to Victor V. Dodonov.

3 recordsLinked to original sources

arXiv2011

Comparing Energy Difference and Fidelity of Quantum States

We look for upper bounds of the relative energy difference of two pure quantum states with a fixed fidelity between them or upper bounds of the fidelity for a fixed relative energy difference. The results depend on the concrete families of states chosen for the comparison. Exact analytical expressions are found for several popular sets of states: coherent, squeezed vacuum, binomial, negative binomial, and coherent phase states. Their consequence is that to guarantee, for example, the relative energy difference less than 10% for quite arbitrary (unknown) coherent states, the fidelity must exceed the level 0.995. For other kinds of states, the restrictions can be much stronger.

quant-ph↗

arXiv2010

Justification of the symmetric damping model of the dynamical Casimir effect in a cavity with a semiconductor mirror

A "microscopic" justification of the "symmetric damping" model of a quantum oscillator with time-dependent frequency and time-dependent damping is given. This model is used to predict results of experiments on simulating the dynamical Casimir effect in a cavity with a photo-excited semiconductor mirror. It is shown that the most general bilinear time-dependent coupling of a selected oscillator (field mode) to a bath of harmonic oscillators results in two equal friction coefficients for the both quadratures, provided all the coupling coefficients are proportional to a single arbitrary function of time whose duration is much shorter than the periods of all oscillators. The choice of coupling in the rotating wave approximation form leads to the "mimimum noise" model of the quantum damped oscillator, introduced earlier in a pure phenomenological way.

quant-ph↗

arXiv1999

Marginal and correlation distribution functions in the squeezed-states representation

Here we consider the Husimi function P for the squeezed states and calculate the marginal and correlation distribution functions when P is projected onto the photon number states. According to the value of the squeezing parameter one verifies the occurence of oscillations and beats as already appointed in the literature. We verify that these phenomena are entirely contained in the correlation function. In particular, we show that since Husimi and its marginal distribution functions satisfy partial differential equations where the squeeze parameter plays the role of time, the solutions (the squeezed functions obtained from initial unsqueezed functions) can be expressed by means of kernels responsible for the propagation of squeezing. From the calculational point of view, this method presents advantages for calculating the marginal distribution functions (compared to a direct integration over one of the two phase-space variables of P) since one can use the symmetry properties of the differential equations.

quant-ph↗