Search results for "quantum optics"
showing 10 items of 143 documents
CONTROL OF RADIATIVE RECOMBINATION BY A STRONG LASER FIELD
2004
Strong-field laser-assisted radiation recombination is investigated: (a) to explore the control possibilities with two laser fields having commensurable frequencies and (b) to get some insight into the influence of the medium (a plasma) in which recombination occurs. It is found that by varying the relative phase of the two fields it is possible to control enhancement, broadening and symmetry properties of the recombination differential emitted power. In the case of an anisotropic two-temperature plasma, an interesting interplay is found between the shape of the laser-modified electron velocity distribution function and the shape of the emitted X-ray photon power spectrum. The novel feature…
Dynamics of H2 molecule driven by an ultra-short laser field
2004
We describe, using a semiclassical approach, the molecular dynamics of a one-dimensional H2 molecule interacting with a laser, beyond the Born–Oppenheimer approximation. We observe and discuss different molecular behaviors, such as ionization and dissociation.
A proposed quantum mechanics mechanism for (e−, h+) charges separation applied to photosynthesis and energy production efficiency improovement
2009
Based on concepts in semiconductor band gap engineering (the staggered one), a qualitative model is proposed for the first step mechanism in artificial catalysis and natural systems such as photosynthesis in green leaves.
Coherent control of stimulated emission process inside one-dimensional photonic crystals
2005
The control of the stimulated emission processes in a 1D PC is discussed. A non-canonical quantization is adopted (QNM). The decay rate of the stimulated emission depends on the cavity and phase-difference of the pumps.
Resonant atom-field interaction in large-size coupled-cavity arrays
2011
We consider an array of coupled cavities with staggered inter-cavity couplings, where each cavity mode interacts with an atom. In contrast to large-size arrays with uniform-hopping rates where the atomic dynamics is known to be frozen in the strong-hopping regime, we show that resonant atom-field dynamics with significant energy exchange can occur in the case of staggered hopping rates even in the thermodynamic limit. This effect arises from the joint emergence of an energy gap in the free photonic dispersion relation and a discrete frequency at the gap's center. The latter corresponds to a bound normal mode stemming solely from the finiteness of the array length. Depending on which cavity …
Quantum state transfer in imperfect artificial spin networks
2005
High-fidelity quantum computation and quantum state transfer are possible in short spin chains. We exploit a system based on a dispersive qubit-boson interaction to mimic XY coupling. In this model, the usually assumed nearest-neighbors coupling is no more valid: all the qubits are mutually coupled. We analyze the performances of our model for quantum state transfer showing how pre-engineered coupling rates allow for nearly optimal state transfer. We address a setup of superconducting qubits coupled to a microstrip cavity in which our analysis may be applied.
Diffusion and transfer of entanglement in an array of inductively coupled flux qubits
2007
A theoretical scheme to generate multipartite entangled states in a Josephson planar-designed architecture is reported. This scheme improves the one published in [Phys. Rev. B 74, 104503 (2006)] since it speeds up the generation of W entangled states in an MxN array of inductively coupled Josephson flux qubits by reducing the number of necessary steps. In addition, the same protocol is shown to be able to transfer the W state from one row to the other.
Quantum cloning in spin networks
2004
We introduce an approach to quantum cloning based on spin networks and we demonstrate that phase covariant cloning can be realized using no external control but only with a proper design of the Hamiltonian of the system. In the 1 -> 2 cloning we find that the XY model saturates the value for the fidelity of the optimal cloner and gives values comparable to it in the genera N -> M case. We finally discuss the effect of external noise. Our protocol is much more robust to decoherence than a conventional procedure based on quantum gates.
Heat flux and quantum correlations in dissipative cascaded systems
2015
We study the dynamics of heat flux in the thermalization process of a pair of identical quantum systems that interact dissipatively with a reservoir in a cascaded fashion. Despite that the open dynamics of the bipartite system $S$ is globally Lindbladian, one of the subsystems ``sees'' the reservoir in a state modified by the interaction with the other subsystem and hence it undergoes a non-Markovian dynamics. As a consequence, the heat flow exhibits a nonexponential time behavior which can greatly deviate from the case where each party is independently coupled to the reservoir. We investigate both thermal and correlated initial states of $S$ and show that the presence of correlations at th…
Collisional picture of quantum optics with giant emitters
2020
The effective description of the weak interaction between an emitter and a bosonic field as a sequence of two-body collisions provides a simple intuitive picture compared to traditional quantum optics methods as well as an effective calculation tool of the joint emitter-field dynamics. Here, this collisional approach is extended to many emitters (atoms or resonators), each generally interacting with the field at many coupling points ("giant" emitter). In the regime of negligible delays, the unitary describing each collision in particular features a contribution of a chiral origin resulting in an effective Hamiltonian. The picture is applied to derive a Lindblad master equation (ME) of a set…