Density matrix approach to photon-assisted tunneling in the transfer Hamiltonian formalism

被引:8
作者
Davids, Paul S. [1 ]
Shank, Joshua [1 ]
机构
[1] Sandia Natl Labs, Albuquerque, NM 87185 USA
基金
美国能源部;
关键词
ZERO-BIAS ANOMALIES; MANY-PARTICLE POINT; QUANTUM DOTS; OF-VIEW; SUPERCONDUCTORS; MICROWAVE; TRANSPORT; DIODE;
D O I
10.1103/PhysRevB.97.075411
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The transfer Hamiltonian tunneling current is derived in a time-dependent densitymatrix formulation and is used to examine photon-assisted tunneling. Bardeen's tunneling expression arises as the result of first-order perturbation theory in a mean-field expansion of the density matrix. Photon-assisted tunneling from confined electromagnetic fields in the forbidden tunnel barrier region occurs due to time-varying polarization and wave-function overlap in the gap which leads to a nonzero tunneling current in asymmetric device structures, even in an unbiased state. The photon energy is seen to act as an effective temperature-dependent bias in a uniform barrier asymmetric tunneling example problem. Higher-order terms in the density matrix expansion give rise to multiphoton enhanced tunneling currents that can be considered an extension of nonlinear optics where the nonlinear conductance plays a similar role as the nonlinear susceptibilities in the continuity equations.
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页数:9
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