arXiv subjects

A. V. Chizhov

Publications and source records attributed to A. V. Chizhov.

5 recordsLinked to original sources

arXiv2013

A geometrical crossover in excited states of two-electron quantum dots in a magnetic field

We use the entanglement measure to study the evolution of quantum correlations in two-electron axially-symmetric parabolic quantum dots under a perpendicular magnetic field. We found that the entanglement indicates on the shape transition in the density distribution of two electrons in the lowest state with zero angular momentum projection at the specific value of the applied magnetic field.

cond-mat.mes-hall↗

arXiv2008

Entanglement control in coupled two-mode boson systems

A two-mode boson model, widely used for the physics of fast rotating nuclei and Bose-Einstein condensates, is studied in the context of entanglement control. We derive an analytical expression for the entanglement between the fields in this model as a function of time. We found that depending on the interaction strengths between boson modes and the nature of the initial boson states the dynamical evolution of the entanglement and the squeezing can occur independently.

quant-ph↗

arXiv2001

Continuous-variable quantum teleportation through lossy channels

The ultimate limits of continuous-variable single-mode quantum teleportation due to absorption are studied, with special emphasis on (quasi-)monochromatic optical fields propagating through fibers. It is shown that even if an infinitely squeezed two-mode squeezed vacuum were used, the amount of information that would be transferred quantum mechanically over a finite distance is limited and effectively approaches to zero on a length scale that is much shorter than the (classical) absorption length. Only for short distances the state-dependent teleportation fidelity can be close to unity. To realize the largest possibly fidelity, an asymmetrical equipment must be used, where the source of the two-mode squeezed vacuum is nearer to Alice than to Bob and in consequence the coherent displacement performed by Bob cannot be chosen independently of the transmission lengths.

quant-ph↗

arXiv2001

Propagation of entangled light pulses through dispersive and absorbing channels

The modification of initially entangled light pulses passing through dispersive and absorbing four-port devices is studied, using recently obtained results on quantum state transformations [Phys. Rev. A 59, 4716 (1999)]. The fidelity and indices of quantum correlations based on the von Neumann entropy are calculated. Their dependence on both the pulse shape and the four-port device parameters is studied. It is shown, that due to dispersion and absorption the quantum correlations are reduced substantially for large initial entanglement.

quant-ph↗

arXiv1998

A two-step optimized measurement for the phase-shift

A two-step detection strategy is suggested for the precise measurement of the optical phase-shift. In the first step an unsharp, however, unbiased joint measurement of the phase and photon number is performed by heterodyning the signal field. Information coming from this step is then used for suitable squeezing of the probe mode to obtain a sharp phase distribution. Application to squeezed states leads to a phase sensitivity scaling as $Δϕ\simeq N^{-1}$ relative to the total number of photons impinged into the apparatus. Numerical simulations of the whole detection strategy are also also presented.

quant-ph↗