Baiwen Li

Improving the capacity of the Bostrom-Felbinger protocol

We show that the capacity of the Bostrom-Felbinger (ping-pong) protocol [Phys. Rev. Lett. 89, 187902 (2002)] can be doubled by introducing two additional unitary operations. In message mode, Alice can use one of the four unitary operations to encode two classical bits of information. Bob can decode Alices information by using a Bell-basis measurement. Security against eavesdropping attack can be ensured by using two conjugate measurement bases in control mode. A message authentification method can protect this communication against a man-in-the-middle attack without eavesdropping.

Calculation of the Ground States of H- Ion and He Atom in Magnetic Field with a Modified Configuration Interaction Method

The modified configuration interaction method is extended to double electronic systems in magnetic fields. Eigenvalues and binding energies of ground state of H- ion and He atom in uniform magnetic fields are calculated. In a range running from low to intermediate magnetic fields, the best results with relative errors of 1.0x10(-5) and 1.4x10(-6) for H- and He, respectively are obtained. The accuracy of our results are almost 2 orders of magnitude better than those obtained by the other methods.