Calculated Momentum Dependence of Zhang-Rice States in Transition Metal Oxides

Using a combination of local density functional theory and cluster exact diagonalization based dynamical mean field theory, we calculate many body electronic structures of several Mott insulating oxides including undoped high T_{c} materials. The dispersions of the lowest occupied electronic states are associated with the Zhang-Rice singlets in cuprates and with doublets, triplets, quadruplets and quintets in more general cases. Our results agree with angle resolved photoemission experiments including the decrease of the spectral weight of the Zhang--Rice band as it approaches k=0

Sensitive Chemical Compass Assisted by Quantum Criticality

The radical-pair-based chemical reaction could be used by birds for the navigation via the geomagnetic direction. An inherent physical mechanism is that the quantum coherent transition from a singlet state to triplet states of the radical pair could response to the weak magnetic field and be sensitive to the direction of such a field and then results in different photopigments in the avian eyes to be sensed. Here, we propose a quantum bionic setup for the ultra-sensitive probe of a weak magnetic field based on the quantum phase transition of the environments of the two electrons in the radical pair. We prove that the yield of the chemical products via the recombination from the singlet state is determined by the Loschmidt echo of the environments with interacting nuclear spins. Thus quantum criticality of environments could enhance the sensitivity of the detection of the weak magnetic field.Comment: 4 pages, 3 figure

Quenched Charmed Meson Spectra using Tadpole Improved Quark Action on Anisotropic Lattices

Charmed meson charmonium spectra are studied with improved quark actions on anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion relations for 4 lowest lattice momentum modes with quark mass values ranging from the strange quark to charm quark with 3 different values of gauge coupling $\beta$ and 4 different values of bare speed of light $\nu$. With the bare speed of light parameter $\nu$ tuned in a mass-dependent way, we study the mass spectra of $D$, $D_s$, $\eta_c$, $D^{\ast}$, $D_s^{\ast}$ and $J/\psi$ mesons. The results extrapolated to the continuum limit are compared with the experiment and qualitative agreement is found.Comment: 8 pages, 2 figures, latex fil

Ground state properties of one-dimensional Bose-Fermi mixtures

Bose-Fermi mixtures in one dimension are studied in detail on the basis of an exact solution. Corresponding to three possible choices of the referecce state in the quantum inverse scattering method, three sets of Bethe-ansatz equations are derived explicitly. The features of the ground state and low-lying excitations are investigated. The ground state phase diagram caused by the external field and chemical potential is obtained

Finite-Temperature Scaling of Magnetic Susceptibility and Geometric Phase in the XY Spin Chain

We study the magnetic susceptibility of 1D quantum XY model, and show that when the temperature approaches zero, the magnetic susceptibility exhibits the finite-temperature scaling behavior. This scaling behavior of the magnetic susceptibility in 1D quantum XY model, due to the quantum-classical mapping, can be easily experimentally tested. Furthermore, the universality in the critical properties of the magnetic susceptibility in quantum XY model is verified. Our study also reveals the close relation between the magnetic susceptibility and the geometric phase in some spin systems, where the quantum phase transitions are driven by an external magnetic field.Comment: 6 pages, 4 figures, get accepted for publication by J. Phys. A: Math. Theo

Nonsequential Double Ionization with Polarization-gated Pulses

We investigate laser-induced nonsequential double ionization by a polarization-gated laser pulse, constructed employing two counter-rotating circularly polarized few cycle pulses with a time delay $T_{d}$. We address the problem within a classical framework, and mimic the behavior of the quantum-mechanical electronic wave packet by means of an ensemble of classical electron trajectories. These trajectories are initially weighted with the quasi-static tunneling rate, and with suitably chosen distributions for the momentum components parallel and perpendicular to the laser-field polarization, in the temporal region for which it is nearly linearly polarized. We show that, if the time delay $T_{d}$ is of the order of the pulse length, the electron-momentum distributions, as functions of the parallel momentum components, are highly asymmetric and dependent on the carrier-envelope (CE) phase. As this delay is decreased, this asymmetry gradually vanishes. We explain this behavior in terms of the available phase space, the quasi-static tunneling rate and the recollision rate for the first electron, for different sets of trajectories. Our results show that polarization-gating technique may provide an efficient way to study the NSDI dynamics in the single-cycle limit, without employing few-cycle pulses.Comment: 17 pages, 6 figure