Effect of quantum entanglement on Aharonov-Bohm oscillations, spin-polarized transport and current magnification effect

We present a simple model of transmission across a metallic mesoscopic ring. In one of its arm an electron interacts with a single magnetic impurity via an exchange coupling. We show that entanglement between electron and spin impurity states leads to reduction of Aharonov-Bohm oscillations in the transmission coefficient. The spin-conductance is asymmetric in the flux reversal as opposed to the two-probe electrical conductance which is symmetric. In the same model, in contradiction to the naive expectation of a current magnification effect, we observe enhancement as well as suppression of this effect depending on the system parameters. The limitations of this model to the general notion of dephasing or decoherence in quantum systems are pointed out.     

Neutron correlations in the 41K ground state and T = 1 2p-2h states in 40K

Differential cross sections have been measured for ⁴¹(d, t)⁴⁰K and ⁴¹K(p, d)⁴⁰K at 15 MeV using a magnetic spectrograph with electronic detection by proportional-counter-scintillator telescopes or semiconductor detectors. Knowledge of the structure of the ⁴⁰K multiplets ($\text{ν}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{, π}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$) and ($\text{ν}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{, π}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$) permits the determination of amplitudes and relative phases for various configurations and neutron correlations in the ⁴¹K ground state. Spectroscopic factors for neutron pick-up to states in ⁴⁰K are strongly influenced by the interference of transition amplitudes. In the (d, t) reaction T= 1, 2p-2h states are also observed.