| Description: |
The interaction of quantum systems with an environment typically results in the loss of quantum coherence and energy dissipation. In this thesis, we employ state-of-the-art matrix-product state (MPS) methods to study the impact of quantum environments of increasing complexity on few-body and many-body systems. The simplest case is that of Markovian (i.e. memoryless) environments that couple weakly to the system of interest. The effects of such environments can be accounted for implicitly via the Lindblad master equation, and we call them dissipative environments. In these setups, the peculiar phenomenon of “hot systems cooling faster than cold systems”, known as the Mpemba effect, has recently attracted much attention. Here, we define the quantum Mpemba effect in a thermodynamically consistent way and show how to exponentially accelerate the thermalization of arbitrary mixed quantum states. When the interaction with the system is strong and/or long memory effects are present, one must account for the environment explicitly. Important instances of such environments are vibrational environments when they are characterized by a low temperature, a non-trivial spectral density, or a strong coupling to the system of interest. In condensed matter physics, quantized lattice vibrations, known as phonons, play a crucial role in determining different properties of solids. In this context, an interesting recent class of experiments consists in optically exciting phonon modes and measuring the electronic response out of equilibrium. Here, we introduce a numerical method dubbed phonon state tomography (PST) as a novel tool for investigating the effect of phonon excitations on electron dynamics. Applying PST to study a model for a one-dimensional (1D) photo-excited metal at low phonon frequencies, we find an enhancement of light-induced longrange electron correlation. We also explore the effect of joined dissipative and vibrational environments on electrons. Combining a Markovian-embedding method with a pure-state unraveling, ... |