arXiv subjects

B. Baseia

Publications and source records attributed to B. Baseia.

At least 19 recordsLinked to original sources

arXiv2016

Dispersive Jaynes-Cummings Hamiltonian describing a two-level atom interacting with a two-level single mode field

We investigate the time evolution of statistical properties of a single mode radiation field after its interaction with a two-level atom. The entire system is described by a dispersive Jaynes-Cummings Hamiltonian assuming the atomic state evolving from an initial superposition of its excited and ground states, $\vert e\rangle +\vert g\rangle ,$ and the field evolving from an initial superposition of two excited levels, $\vert n_{1}\rangle+ \vert n_{2}\rangle$. It is found that the field evolution is periodic, the period depending on the ratio $n_{2}/n_{1}.$ The energy excitation oscillates between these two states and the statististics can be either sub- or super-Poissonian, depending on the values $n_{1},$ $n_{2}$.

quant-ph↗

arXiv2016

On the paradoxical evolution of the number of photons in a new model of interpolating Hamiltonians

We introduce a new Hamiltonian model which interpolates between the Jaynes-Cummings model and other types of such Hamiltonians. It works with two interpolating parameters, rather than one as traditional. Taking advantage of this greater degree of freedom, we can perform continuous interpolation between the various types of these Hamiltonians. As applications we discuss a paradox raised in literature and compare the time evolution of photon statistics obtained in the various interpolating models. The role played by the average excitation in these comparisons is also highlighted.

quant-ph↗

arXiv2015

Controlling properties of a hybrid Cooper pair box interacting with a nanomechanical resonator in the presence of Kerr nonlinearities and losses

We consider the Jaynes-Cummings model describing the interaction of a Cooper pair box (CPB) and a nanoresonator (NR) in the presence of a Kerr medium and losses The evolution of the entropy of both subsystems and the CPB population inversion were calculated numerically. It is found that these properties increase when the NR frequency is time-dependent, even in the presence of losses; the effect is very sensitive to detuning and disappears in the resonant regime. The roles played by the losses affecting the CPB and the NR are also compared.

quant-ph↗

arXiv2015

Controlling the nonclassical properties of a hybrid Cooper pair box system and an intensity dependent nanomechanical resonator

We employ a more realistic treatment to investigate the entropy and the excitation-inversion of a coupled system that consists of a nanomechanical resonator and a superconducting Cooper pair box. The procedure uses the Buck-Sukumar model in the microwave domain, considers the nanoresonator with a time dependent frequency and both subsystems in the presence of losses. Interesting results were found for the temporal evolutions of the entropy of each subsystem and of the excitation-inversion in the Cooper pair box. A comparison was also performed about which of these two subsystems is more sensitive to the presence of losses. The results suggest that appropriate choices of the involved time dependent parameters allow us to monitor these two features of the subsystems and may offer potential applications, e.g., in the generation of nonclassical states, quantum communication, quantum lithography.

quant-ph↗

arXiv2015

Some Aspects of Quantum Optics Using Light Fields in Traveling Waves

Although the theoretical treatment to describe the light field in Quantum Optics was generic, during large time it was predominantly related to optical modes trapped inside cavities. Important results were then obtained in this scenario. However, in view of the practical difficulties due to the deleterious effects of decoherence upon states of trapped fields, many physicists in this area began to focus more emphasis in the treatment using traveling fields. This brief report concerns with engineering non-classical states of light field to show some details and applications in the later scenario. Here the interaction "atom-trapped field", is translated to the interaction "beam splitter-traveling field".

quant-ph↗

arXiv2011

Controlling Excitations Inversion of a Cooper Pair Box Interacting with a Nanomechanical Resonator

We investigate the action of time dependent detunings upon the excitation inversion of a Cooper pair box interacting with a nanomechanical resonator. The method employs the Jaynes-Cummings model with damping, assuming different decay rates of the Cooper pair box and various fixed and t-dependent detunings. It is shown that while the presence of damping plus constant detunings destroy the collapse/revival effects, convenient choices of time dependent detunings allow one to reconstruct such events in a perfect way. It is also shown that the mean excitation of the nanomechanical resonator is more robust against damping of the Cooper pair box for convenient values of t-dependent detunings.

cond-mat.supr-con↗

arXiv2011

Hole burning in a nanomechanical resonator coupled to a Cooper pair box

We propose a scheme to create holes in the statistical distribution of excitations of a nanomechanical resonator. It employs a controllable coupling between this system and a Cooper pair box. The success probability and the fidelity are calculated and compared with those obtained in the atom-field system via distinct schemes. As an application we show how to use the hole-burning scheme to prepare (low excited) Fock states.

quant-ph↗

arXiv2011

Controlled teleportation via photonic Faraday rotations in low-Q cavities

This paper presents feasible experimental schemes to realize controlled teleportation protocols via photonic Faraday rotations in low-Q cavities. The schemes deal with controlled teleportation of superposition states and two-particle entanglement of atomic states. The information is encoded in three-level atoms in a lambda configuration trapped inside coupled cavities by optical fibers. Also, we estimate the success probability and the current feasibility of the schemes.

quant-ph↗

arXiv2010

Alternative scheme to generate a supersinglet state of three-level atoms

In this paper we propose an alternative scheme to generate a supersinglet state of three three-level atoms via a single-mode of a cavity QED based on the two-photon transitions described by the 'full microscopical Hamiltonian approach'. In it, three three-level atoms prepared in suitable initial states are sequentially sent through the cavity originally prepared in its vacuum state. After an appropriate choice of the atom-cavity interaction times plus a field detection the state that describes the whole atom-field system is projected in the desired supersinglet state. The fidelity and success probability of the state as well as the practical feasibility of the scheme are discussed.

quant-ph↗

arXiv2010

Entanglement swapping of atomic states through the photonic Faraday rotation

We propose an entanglement swapping of atomic states confined by cavities QED using a photonic Faraday rotation. Two schemes are considered in which we use three and four cavities, respectively, plus an additional circularly-polarized photon. After interacting with an atom trapped inside the cavity the system evolves to an entangled atom-photon state. The entanglement swapping is then achieved by a Bell-state measurement upon the entire atom-photon state.

quant-ph↗

arXiv2010

Generation of two-photon EPR and Wstates

In this paper we present a scheme for generation of two-photon EPR and W states in the cavity QED context. The scheme requires only one three-level Rydberg atom and two or three cavities. The atom is sent to interact with cavities previously prepared in vacuum states, via two-photon process. An appropriate choice of the interaction times one obtains the mentioned state with maximized fidelities. These specific times and the values of success probability and fidelity are discussed.

quant-ph↗

arXiv2009

Splitting of quantum information in traveling wave fields using only linear optical elements

In this brief report we present a feasible scheme to split quantum information in the realm of traveling waves. An oversimplified scheme is also proposed for the generation of a class of W states useful for perfect teleportation and superdense coding. The scheme employs only linear optical elements as beam splitters and phase shifters, in addition to photon counters and one-photon sources. It is shown that splitting of quantum information with high fidelity is possible even including inefficiency of the detectors and photoabsorption of the beam splitters.

quant-ph↗

arXiv2009

Quantum teleportation in superconducting charge qubits

In this paper we propose a scheme to implement a quantum teleportation based on the current experimental design [Nature (London) 431, 162 (2004); ibid 445, 515 (2007)] in which superconducting charge qubits are capacitively coupled to a single high-Q superconducting coplanar resonator. As advantage of this architecture, it permits the use of multiqubit gates between non-nearest qubits and the realization of parallel gates. We consider the case of two qubits inside the resonator, where the teleportation is accomplished.

quant-ph↗

arXiv2009

Generation of four-qubit cluster of entangled coherent states in bimodal QED cavities

A recent work [1] proposed a type of cluster entangled coherent states and its generation. Here we present an alternative experimental arrangement for its generation in bimodal QED cavities. The scheme employs a single two-level atom that interacts dispersively with cavity modes initially prepared in coherent states. The fidelity and success probability of the state preparation are obtained considering the influence of atomic velocity spread and atomic efficiency detection.

quant-ph↗

arXiv2008

Generation of arbitrary Fock states via resonant interactions in cavity QED

We propose a scheme to generate arbitrary Fock states |N> in a cavity QED using N resonant Rydberg atoms. The atom-field interaction times are controlled via Stark-shifts adjusted in a way that each atom transfers a photon to the cavity, turning atomic detections useless. Fluctuations affecting the control of the atom-field interactions are also considered.

quant-ph↗

arXiv2007

Conditional displacement operator for traveling fields

We show that the conditional displacement operator $\hat{U}_{CD}=\exp [\hat{b}^{\dagger}\hat{b}(β\hat{a}^{\dagger}-β^{\ast}\hat{a})]$ acting upon an arbitrary state of traveling waves can be well approximated by the action of a Kerr medium placed between two beam splitters whose respective second ports are fed by highly excited coherent states. Applications to the generation of nonclassical states and measurement of Wigner function of arbitrary states are also considered.

quant-ph↗

arXiv2007

Exchange of quantum states between coupled oscillators

Exchange of quantum states between two interacting harmonic oscillator along their evolution time is discussed. It is analyzed the conditions for such exchange starting from a generic initial state and demonstrating that the effect occurs exactly only for the particular states C0|0>+Cn|N>, which includes the interesting qubits components |0>,|1>. It is also determined the relation between the coupling constant and characteristic frequencies of the oscillators to have the complete exchange.

quant-ph↗

arXiv2006

Teleportation of entangled states without Bell-state measurement

In a recent paper [Phys. Rev. A 70, 025803 (2004)] we presented a scheme to teleport an entanglement of zero- and one-photon states from a bimodal cavity to another one, with 100% success probability. Here, inspired on recent results in the literature, we have modified our previous proposal to teleport the same entangled state without using Bell-state measurements. For comparison, the time spent, the fidelity, and the success probability for this teleportation are considered.

quant-ph↗