Related papers: Quantum magnets with weakly confined spinons: Mult…
We show that quantum correlations as quantified by quantum discord can characterize quantum phase transitions by exhibiting nontrivial long-range decay as a function of distance in spin systems. This is rather different from the behavior of…
Decoherence in Nature has become one of the most pressing problems in physics. Many applications, including quantum information processing, depend on understanding it; and fundamental theories going beyond quantum mechanics have been…
The ground states of few electrons confined in two vertically coupled quantum rings in the presence of an external magnetic field are studied systematically within the current spin-density functional theory. Electron-electron interactions…
The effect of a magnetic field on a gapped quantum magnet is described within the framework of the Quantum Dimer Model. A minimal model describing the proliferation of itinerant spinons above a critical field is proposed and investigated by…
We study the effects of quantum fluctuations in magnetic properties of quantum frustrated ferromagnets in a magnetic field. It is shown that a non-classical phase or a phase separation appears due to quantum fluctuations below the…
We analyze the entanglement properties of spins (qubits) attached to the boundary of spin chains near quantum critical points, or to dissipative environments, near a boundary critical point, such as Kondo-like systems or the dissipative two…
The emergence of a diverging length scale in many-body systems at a quantum phase transition implies that total entanglement has to reach its maximum there. In order to fully characterize this, one has to consider multipartite entanglement…
The properties of mobile impurities in quantum magnets are fundamental for our understanding of strongly correlated materials and may play a key role in the physics of high-temperature superconductivity. Hereby, the motion of hole-like…
Strongly interacting one-dimensional quantum systems often behave in a manner that is distinctly different from their higher-dimensional counterparts. When a particle attempts to move in a one-dimensional environment it will unavoidably…
Static and dynamical properties of weakly coupled antiferromagnetic spin chains are treated using a mean--field approximation for the interchain coupling and exact results for the resulting effective one--dimensional problem. Results for…
The magnetic behavior of antiferromagnetic spin 1/2 chains with site-centered impurities in a magnetic field is investigated. The effect of impurities is implemented by considering different situations of both diagonal and off-diagonal…
We study quantum spin ice in an external magnetic field applied along a $<100>$ direction. When quantum spin fluctuations are weak, elementary excitations are quantum strings with monopoles at their ends manifested as multiple spin-wave…
A scaling theory of the Kondo lattices with frustrated exchange interactions is developed, criterium of antiferromagnetic ordering and quantum-disordered state being investigated. The calculations taking into account magnon and incoherent…
A scenario of quantum computing process based on the manipulation of a large number of nuclear spins in Quantum Hall (QH) ferromagnet is presented. It is found that vacuum quantum fluctuations in the QH ferromagnetic ground state at filling…
The quantum coherent coupling of completely different degrees of freedom is a challenging path towards creating new functionalities for quantum electronics. Usually the antagonistic coupling between spins of magnetic impurities and…
We study the effect of site dilution and quantum fluctuations in an antiferromagnetic spin system on a square lattice within the linear spin-wave approximation. By performing numerical diagonalization in real space and finite-size scaling,…
We study a localized spin coupled to an Anderson impurity to model the situation found in higher transition metal or rare earth compounds like e.g.\ LaMnO$_3$ or Gd monopnictides. We find that, even for large quantum numbers of the…
Understanding how quasi-particles interact with impurities is crucial for unveiling novel properties of quantum many-body systems. A prominent example is the enhanced scattering between electrons and magnetic impurities in the low-energy…
Electron spin relaxation in a spin-polarized quantum Hall state is studied. Long spin relaxation times that are at least an order of magnitude longer than those measured in previous experiments were observed and explained within the…
There has been considerable debate on the onset of exotic spin phenomena in quantum wires due to enhanced many-body effects caused by the one-dimensional (1D) alignment of charge carriers. We explain various observed spin effects, such as a…