Strongly Driven 2,3,6 Level Quantum Systems

Principal Investigator

John Martin

Laser Physics Centre,

Research School of Physical Sciences and Engineering

The excitation of transitions within quantum systems by one or more resonant intense electromagnetic fields produces nonlinear effects such as lasing without inversion and electromagnetically induced transparency. Over the last 15 years such effects have observed experimentally and much theoretical work has been produced. Most of this work has involved only 2 or 3 level systems. The Nitrogen Vacancy (NV) centre in Diamond is an experimental system that the Solid State Spectroscopy group of the Laser Physics Centre has been investigating. While we have investigated experimental conditions where the nonlinear behaviour can be modelled as strongly driven 2 or 3 level systems the NV centre really is a 6 level system. Since the experiments in the group have been getting more complex, proper consideration of the presence of 6 levels is required. Further the presence of extra levels has been conjectured to lead to enhancement of nonlinear effects observed in 2 or 3 level systems.    


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What are the results to date and the future of the work?

A set of 5 theoretical spectra simulating the weak z-polarized probe response of the 6 level NV model for varying strengths of a z-polarized pump field resonant with the Rabi transition induced by a xy-polarized pump field have been completed, see fig. 1. This simulated spectra mimics real experimental data on the NV centre in Diamond. The positions of the peaks present in the spectra is in good agreement with experiment. Indeed due to lack of noise in the simulated spectra several minor experimental peaks have been confirmed as real.

The next step is to get the intensities of the transitions in agreement with experiment. This entails varying the population and relaxation parameters involved in the model. Due to the slowness of updated software (see below) less complex experiments involving fewer electromagnetic fields will be modelled to allow more efficient testing of appropriate population and relaxation parameters prior to further calculations on original experiment.

- Appendix A


What computational techniques are used?

The simulated spectra in fig. 1 arise from the solution of 1360 coupled equations. The mathematical package Mathematica is used. This package is very efficient at setting up the coupled equations and extracting the required components of the calculations.



Appendix A -