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Showing 1 to 8 of 8 for “"reduced density matrix"”.
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Quantum information and thermodynamics of general relativity
… field. We derive the evolution equations for the reduced density matrix of the detector, invoking neither the Markov approximation nor the Rotating Wave Approximation (RWA). We find that at early times and in the regime of small accelerations, the non-Markovian effects are particularly pronounced, …
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Scaling of entanglement entropy in some condensed matter systems
… three main parts. Chapter 2 studies the thermal reduced density matrices in fermion and spin systems on ladders. Chapter 3 studies the many-body localization phase transition in a Rokhsar-Kivelson type wave function. Chapter 4 studies the subleading correction term of entanglement entropy in 2+1 …
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Exact and variational investigations of Hubbard rings
… Our results are valid for arbitrary electron density values. The variational techniques we use are applied to the two-particle reduced-density matrix (2-RDM), because this quantity suffices to obtain expectation values of all one- and two-particle operators, and because it is less …
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Correlated electron transport across atomic and molecular tunnel junctions
… NEGF+DFT non-equilibrium Green’s function plus density functional theory. Typical single particle treatments are incomplete due to approximations made in the treatment of the electronic structure leading to discrepancies between theory and experiment by orders of magnitude, believed to be due to …
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Spectral and dynamical properties of disordered and noisy quantum spin models
… equation, namely the relaxation of the one-spin reduced density matrix is determined, but this affords little insight and extension to two-spin quantities is difficult. We change our approach in Chapter 3, studying instead a stroboscopic version of the model using the formalism of quantum graphs. …
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Photoionization of atoms with ultrashort XUV laser pulses at extreme intensities
… a small number of electrons, the time-dependent reduced density matrix formalism is implemented on the Hartree-Fock level as well as one level above and thus accounts also for a correlated electron-electron interaction. Furthermore, for the ionization of resonantly driven atomic bound states an …
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Multiphoton correlations and emitters
The characterisation of the quantum states of light and their subsequent realisation is thought to be an indispensable step to bring in quantum technologies to the real world. The emergence of quantum cryptography, quantum security protocols or quantum computers, among others, demand implicitly or …
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Coherent ionization dynamics induced by intense X-ray free-electron laser pulses
… the one hand, the coupling to the continuum is reduced to the rate-equation level while possible Rabi cycling between the two discrete states is fully taken into account. The rate-equation approach, on the other hand, further simplifies the situation by treating the two-level system analogous to …