a noninteracting quantum-dot arrays side coupled to a quantum wire is studied. transport through the quantum wire is investigated by using a noninteracting anderson tunneling hamiltonian. the conductance at zero temperature develops an oscillating band with resonances and antiresonances due to constructive and destructive interference in the ballistic channel, respectively. moreover, we have fo...

Recent studies of strongly interacting atoms and photons in optical cavities have rekindled interest in the Dicke model of atomic qubits coupled to discrete photon cavity modes. We study the multimode Dicke model with variable atom-photon couplings. We argue that a quantum spin-glass phase can appear, with a random linear combination of the cavity modes superradiant. We compute atomic and photo...

A classical interaction model for the calculation of molecular polarizabilities has been investigated. The model is described by atomic capacitancies, polarizabilities, and a parameter related to the size of the atom, where one set of parameters has been employed for each element. The model has been parameterized for the elements H, C, N, O, F, and Cl from quantum chemical calculations of the m...

Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experime...

A quantum theory of a two and three-level laser with injected atomic coherence is developed by using a density operator method, to the best of our knowledge, for the first time. The initial atomic coherence plays an essential role. At steady state, the equation of motion for the density operator yields to exhibit laser without inversion and a phase locking but no threshold for the laser fie...

We study the dynamics of an atomic quantum dot, i.e., a single atom in a tight optical trap which is coupled to a superfluid reservoir via laser transitions. Quantum interference between the collisional interactions and the laser induced coupling results in a tunable dot-bath coupling, allowing an essentially complete decoupling from the environment. Quantum dots embedded in a 1D Luttinger liqu...

We describe nonlinear quantum atom–light interfaces and nonlinear quantum metrology in the collective continuous variable formalism. We develop a nonlinear effective Hamiltonian in terms of spin and polarization collective variables and show that model Hamiltonians of interest for nonlinear quantum metrology can be produced in 87Rb ensembles. With these Hamiltonians, metrologically relevant ato...

Introduction 1. Computing at the atomic scale 2. Reversible computation 3. Classical universal machines and logic gates 3.1. FANOUT and ERASE 3.2. Computation without ERASE 4. Elementary quantum notation 5. Logic gates for quantum bits 6. Logic gates in the laboratory 7. Model quantum computer and quantum code 8. Quantum parallelism: Period of a sequence 9. The complexity of factoring 10. Secur...