Quantum interference in resonant tunneling and single spin measurements

We consider the resonant tunneling through a multi-level system. It is demonstrated that the resonant current displays quantum interference effects due to a possibility of tunneling through different levels. We show that the interference effects are strongly modulated by a relative phase of states carrying the current. This makes it possible to use these effects for measuring the phase difference between resonant states in quantum dots. We extend our model for a description of magnetotransport through the Zeeman doublets. It is shown that, due to spin-flip transitions, the quantum interference effects generate a distinct peak in the shot-noise power spectrum at the frequency of Zeeman splitting. This mechanism explains modulation in the tunneling current at the Larmor frequency observed in scanning tunneling microscope experiments and can be utilized for a single spin measurement.Comment: Some corrections are made. This paper is based on work presented at the 2004 IEEE NTC Quantum Device Technology Worksho

Two-potential approach to multi-dimensional tunneling

We consider tunneling to the continuum in a multi-dimensional potential. It is demonstrate that this problem can be treated as two separate problems: a) a bound state and b) a non-resonance scattering problem, by a proper splitting of the potential into two components. Finally we obtain the resonance energy and the partial tunneling widths in terms of the bound and the scattering state wave functions. This result can be used in a variety of tunneling problems. As an application we consider the ionization of atomic states by an external field. We obtain very simple analytical expressions for the tunneling width and for the angular distribution of tunneling electrons. It is shown that the angular spread of electrons in the final state is determined by the semi-classical traversal tunneling time.Comment: 13 pages, 1 figure, corrected typos, to appear in ``Multiple Facets of Quantization and Supersymmetry/Michael Marinov Memorial Volume'', World Scientifi