English

Quantum information measures of the Aharonov-Bohm ring in uniform magnetic fields

Quantum Physics 2019-03-08 v2 Mesoscale and Nanoscale Physics Mathematical Physics math.MP

Abstract

Shannon quantum information entropies Sρ,γS_{\rho,\gamma}, Fisher informations Iρ,γI_{\rho,\gamma}, Onicescu energies Oρ,γO_{\rho,\gamma} and complexities eSOe^SO are calculated both in position (subscript ρ\rho) and momentum (γ\gamma) spaces for azimuthally symmetric 2D nanoring that is placed into combination of transverse uniform magnetic field B\bf B and Aharonov-Bohm (AB) flux ϕAB\phi_{AB} and whose potential profile is modeled by superposition of quadratic and inverse quadratic dependencies on radius rr. Increasing intensity BB flattens momentum waveforms Φnm(k)\Phi_{nm}({\bf k}) and in the limit of infinitely large fields they turn to zero, what means that the position wave functions Ψnm(r)\Psi_{nm}({\bf r}), which are their Fourier counterparts, tend in this limit to the δ\delta-functions. Position (momentum) Shannon entropy depends on the field BB as a negative (positive) logarithm of ωeff(ω02+ωc2/4)1/2\omega_{eff}\equiv\left(\omega_0^2+\omega_c^2/4\right)^{1/2}, where ω0\omega_0 determines the quadratic steepness of the confining potential and ωc\omega_c is a cyclotron frequency. This makes the sum Sρnm+Sγnm{S_\rho}_{nm}+{S_\gamma}_{nm} a field-independent quantity that increases with the principal nn and azimuthal mm quantum numbers and does satisfy entropic uncertainty relation. Position Fisher information does not depend on mm, linearly increases with nn and varies as ωeff\omega_{eff} whereas its nn and mm dependent Onicescu counterpart Oρnm{O_\rho}_{nm} changes as ωeff1\omega_{eff}^{-1}. The products IρnmIγnm{I_\rho}_{nm}{I_\gamma}_{nm} and OρnmOγnm{O_\rho}_{nm}{O_\gamma}_{nm} are BB-independent quantities. A dependence of the measures on the ring geometry is discussed. It is argued that a variation of the position Shannon entropy or Onicescu energy with the AB field uniquely determines an associated persistent current as a function of ϕAB\phi_{AB} at B=0B=0. An inverse statement is correct too.

Keywords

Cite

@article{arxiv.1812.10091,
  title  = {Quantum information measures of the Aharonov-Bohm ring in uniform magnetic fields},
  author = {O. Olendski},
  journal= {arXiv preprint arXiv:1812.10091},
  year   = {2019}
}

Comments

11 figures, 1 table