The effect of dissipation on coherent quantum tunnelling in a double-well system: Two-level model using an adjoint equation approach |
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Authors: | A. S. Parkins C. W. Gardiner M. L. Stéyn-Ross |
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Affiliation: | (1) Department of Physics, University of Waikato, Hamilton, New Zealand |
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Abstract: | We examine the effect of dissipation on coherent quantum tunnelling between the two lowest levels of a double-well system using an adjoint equation approach developed previously in the treatment of quantum-optical problems. Dissipation is modelled by a linear coupling to a bath of harmonic oscillators. The high frequency portion of the bath is adiabatically eliminated using a cumulant expansion technique, which generates frequency renormalisation terms. Making a low temperature assumption, an approximate two-level model is developed in the form of three coupled stochastic differential equations. With a decorrelation approximation, the two-level equations can be solved to yield familiar results. However, the adjoint equation also permits the use of direct stochastic simulation as a means of solution, and simulations are carried out for a range of parameters. A comparison with the decorrelation approximation is made. |
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