We present a partition-free approach to the evolution of density matrices for open quantum systems coupled to a harmonic environment. The influence functional for-

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We present an application of the Extended Stochastic Liouville Equation (ESLE) [Phys. Rev. B 95, 125124], which gives an exact solution for the reduced density matrix of an open system surrounded by a harmonic heat bath. This method considers the extended system (the open system and the bath) being thermally equilibrated prior to the action of a time dependent perturbation, as opposed to the usual assumption that system and bath are initially partitioned. This is an exact technique capable of accounting for arbitrary parameter regimes of the model. Here we present our first numerical implementation of the method in the simplest case of a Caldeira-Leggett representation of the bath Hamiltonian, and apply it to a spin-boson system driven from coupled equilibrium. We observe significant behaviours in both the transient dynamics and asymptotic states of the reduced density matrix not present in the usual approximation.arXiv:1712.06397v1 [quant-ph]

We present a framework for controlling the observables of a general correlated electron system driven by an incident laser field. The approach provides a prescription for the driving required to generate an arbitrary predetermined evolution for the expectation value of a chosen observable, together with a constraint on the maximum size of this expectation. To demonstrate this, we determine the laser fields required to exactly control the current in a Fermi-Hubbard system under a range of model parameters, fully controlling the non-linear high-harmonic generation and optically observed electron dynamics in the system. This is achieved for both the uncorrelated metallic-like state and deep in the strongly-correlated Mott insulating regime, flipping the optical responses of the two systems so as to mimic the other, creating 'driven imposters'. We also present a general framework for the control of other dynamical variables, opening a new route for the design of driven materials with customized properties.

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