The Flow Equation Approach to Many Particle Systems Free Download

Over the past decade, the equation method as developed in to satile theoretical approach to quantum many-body physics. Its basic concept was conceived independently by Wegner and by G lazek and Wilson the derivation of a unitary ?ow that makes a many-particle Hamiltonian – creasingly energy-diagonal. This concept can be seen as a generalization of the conventional scaling approache sinmany body physics,where someult- violet energy scale is lowered down to the experimentally relevant low-energy scale [4]. The main difference between the conventional scaling approach and the ?ow equation approach can then be traced back to the fact that the ?ow equation approach retains all degrees of freedom, i. e. the full Hilbert space, while the conventional scaling approach focusses on some low-energy subspace. One useful feature of the ?ow equation approach is therefore that it allows the calculation of dynamical quantities on all energy scales in one uni?ed framework. Since its introduction, a substantial body of work using the equation approach has accumulated.