Polarization of a charge qubit strongly coupled to a voltage-driven quantum point contact.
We study a charge qubit with level splitting epsilon, coupled to a quantum point contact driven by voltage V. In the limit of weak coupling, the qubit polarization shows cusps at epsilon=+/-eV. We show that, for stronger couplings, prominent peculiarities occur at fractions epsilon=+/-eV/2. Further increase of the coupling leads to a polarization corresponding to a pseudo Boltzmann distribution with an effective temperature approximately eV.
Snyman
I
I
Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands.
Nazarov
Y V
YV