A vacuum-adapted approach to quantum Feynman-Kac formulae
  The vacuum-adapted formulation of quantum stochastic calculus is employed to perturb expectation semigroups via a Feynman-Kac formula. This gives an alternative perspective on the perturbation theory for quantum stochastic flows that has recently been developed by the authors. 
Alexander C. R. Belton, J. Martin Lindsay and Adam G. Skalski
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