Marcio H. G. de Miranda

Federal University of Pernambuco | UFPE · Department of Physics

We report the first experimental demonstration of the replica symmetry breaking (RSB) phenomenon in a fiber laser system supporting standard mode-locking (SML) regime. Though theoretically predicted, this photonic glassy phase remained experimentally undisclosed so far. We employ an ytterbium-based mode-locked fiber laser with a very rich phase dia...

By combining a genetic algorithm and spatial light modulator, we theoretically analyze how to improve two-photon cascaded absorption in atomic ensembles, inspecting the impact of various configurations and parameters in the optimized phase mask. At low atomic densities, we compare cases of sequential transitions with two photons coming from the sam...

By combining genetic algorithm and a spatial light modulator we demonstrate theoretically how to improve a two-photon cascade absorption in atomic ensembles using optimized phase masks. At low atomic densities, we compare the cases of sequential transitions with the two photons coming from the same pulse and from two different pulses. We achieved a...

We present an experimental study of the hysteretic behavior of an Yb mode-locked fiber laser (MLFL) in a multi-pulsing regime. Our main focus is on the internal nonlinear transmission curve of the laser, which is fundamental to obtain the mode-locking regime. We have also observed hysteresis in the temporal separation between dispersive bound solit...

Mode-locked fiber lasers are rich dynamical systems that may present several different types of pulsed operating modes, depending on external control parameters such as pump power. A systematic experimental characterization of such regimes is a challenging problem. Here single pulse regimes of ytterbium mode-locked fiber laser are explored and rela...

We report experimental measurements of structural soliton pairs in a mode-locked Yb-doped fiber laser. The quantization of the temporal separation and relative phase between the pair of dissipative solitons is clearly observed and, most interestingly, the transitions between different states as the pump power is varied show abrupt jumps. This is a...

In the present work, we have studied the structural and magnetic properties of Ni and Co nanowires obtained by electrodeposition on alumina membranes. Structural analysis has shown the coexistence of Ni and Co metallic phases as well as NiO and CoO, which are associated to the preparation method. The magnetic study suggests the possibility of unidi...

A study about coercivity as a function of the temperature is presented for nickel nanowires in porous alumina membranes. Changes in coercivity values in temperatures between 50 K and 300 K and results by X-ray diffraction (XRD) suggest that, the effects are motivated by the antiferromagnetic phase transition of small clusters of nickel oxide on the...

We experimentally study the nonlinear dynamics of a femtosecond ytterbium doped mode-locked fiber laser. With the laser operating in the pulsed regime a route to chaos is presented, starting from stable mode-locking, period two, period four, chaos and period three regimes. Return maps and bifurcation diagrams were extracted from time series for eac...

We report the investigation of a collimated blue light generated in rubidium vapor due to the combined action of an ultrashort pulse train and a cw diode laser. Each step of the two-photon transition 5S - 5P$_{3/2}$ - 5D is excited by one of the lasers, and the induced coherence between the 5S and 6P$_{3/2}$ states is responsible for generating the...

We report the investigation of a collimated blue light generated in rubidium vapor due to the combined action of an ultrashort pulse train and a cw diode laser. Each step of the two-photon transition 5S - 5P$_{3/2}$ - 5D is excited by one of the lasers, and the induced coherence between the 5S and 6P$_{3/2}$ states is responsible for generating the...

We characterize a polarization-entangled photon source based on femtosecond pulsed parametric downconversion in a periodically poled χ ( 2 ) medium. Employing a Sagnac interferometer, we prepared different quantum states aiming at future investigations in quantum information and on the foundations of quantum mechanics. In this work we demonstrate t...

We report a detailed investigation on the properties of correlation spectra for cold atoms under the condition of Electromagnetically Induced Transparency (EIT). We describe the transition in the system from correlation to anti-correlation as the intensity of the fields increases. Such transition occurs for laser frequencies around the EIT resonanc...

The phenomenon called Electromagnetically Induced Transparency (EIT) may induce different types of correlation between two optical fields interacting with an ensemble of atoms. It is presently well known, for example, that in the vicinity of an EIT resonance the dominant correlations at low powers turn into anti-correlations as power increases. Suc...

Ultracold polar molecular quantum gases promise to open new research directions ranging from the study of ultra-cold chemistry, precision measurements to novel quantum phase transitions. Based on the preparation of high-phase space density gases of polar KRb molecules in the works of Ni et. al, the authors discussed the control of dipolar collision...

Chemical reaction rates often depend strongly on stereodynamics, namely the orientation and movement of molecules in three-dimensional space. An ultracold molecular gas, with a temperature below 1 uK, provides a highly unusual regime for chemistry, where polar molecules can easily be oriented using an external electric field and where, moreover, th...

Ultracold polar molecules offer the possibility of exploring quantum gases with interparticle interactions that are strong, long-range and spatially anisotropic. This is in stark contrast to the much studied dilute gases of ultracold atoms, which have isotropic and extremely short-range (or 'contact') interactions. Furthermore, the large electric d...

We demonstrate a scheme for direct absorption imaging of an ultracold ground-state polar molecular gas near quantum degeneracy. A challenge in imaging molecules is the lack of closed optical cycling transitions. Our technique relies on photon shot-noise limited absorption imaging on a strong bound-bound molecular transition. We present a systematic...

We report on our ongoing studies of dipolar interactions in ground-state KRb molecules prepared in the quantum regime. At large dipole moment we see a dramatic increase in the inelastic scattering rate due to attractive head-to-tail interactions between molecules [1]. To suppress this inelastic loss we are preparing a gas of polar molecules in a 2D...

Ultracold fermionic polar molecules of ^40K^87Rb in their absolute rovibronic anf hyperfine state [1] have been recently created in a magnetic trap. This enables experiments to probe ultracold molecular chemistry of polar molecules [2] in well defined quantum states. In addition, KRb molecules are polar and can be manipulated by an electric field....

We have studied dipolar collisions in an ultracold molecular gas prepared close to quantum degeneracy [1]. By applying a modest external electric field to fermionic KRb molecules produced in a single quantum state, we tune the dipolar interaction strength in the molecular gas. We observe a steep power law dependence of the chemical reaction rate on...

We prepare a near-quantum-degenerate gas of fermionic KRb molecules, with all the molecules in the absolute lowest energy state. We observe atom-exchange chemical reactions in a regime where the reaction rates are determined by the quantum statistics of the molecules, single partial wave scattering, and quantum threshold laws [1].[4pt] [1] S. Ospel...

How does a chemical reaction proceed at ultralow temperatures? Can simple quantum mechanical rules such as quantum statistics, single partial-wave scattering, and quantum threshold laws provide a clear understanding of the molecular reactivity under a vanishing collision energy? Starting with an optically trapped near–quantum-degenerate gas of pola...

We report the preparation of a rovibronic ground-state molecular quantum gas in a single hyperfine state and, in particular, the absolute lowest quantum state. This addresses the last internal degree of freedom remaining after the recent production of a near quantum degenerate gas of molecules in their rovibronic ground state, and provides a crucia...

The preparation of ultracold polar molecular gases close to quantum degeneracy opens novel research prospects ranging from dipolar quantum many-body physics to ultracold chemistry. With a near quantum degenerate gas of fermionic 40K87Rb polar molecules, this thesis presents studies on dipolar collision and chemical reaction dynamics, exhibiting lon...

How does a chemical reaction proceed at ultralow temperatures? Can simple quantum mechanical rules such as quantum statistics, single scattering partial waves, and quantum threshold laws provide a clear understanding for the molecular reactivity under a vanishing collision energy? Starting with an optically trapped near quantum degenerate gas of po...

We report the creation and characterization of a near quantum-degenerate gas of polar 40K-87Rb molecules in their absolute rovibrational ground state. Starting from weakly bound heteronuclear KRb Feshbach molecules, we implement precise control of the molecular electronic, vibrational, and rotational degrees of freedom with phase-coherent laser fie...

We have produced near quantum degenerate ^40K^87Rb polar molecules in their rovibrational ground state using magneto-association followed by STIRAP transfer. Preliminary measurements show that trap lifetime of these fermion molecules is limited to ˜ 100 ms. We are investigating the KRb loss in the presence of either K or Rb atoms to look for eviden...

A quantum gas of ultracold polar molecules, with long-range and anisotropic interactions, not only would enable explorations of a large class of many-body physics phenomena but also could be used for quantum information processing. We report on the creation of an ultracold dense gas of potassium-rubidium (40K87Rb) polar molecules. Using a single st...

We report on the improved characterization and operation of an optical frequency standard based on nuclear-spin-polarized, ultracold neutral strontium confined in a one dimensional optical lattice. We implement a remote optical carrier phase link between JILA and NIST Boulder Campus, permitting high precision evaluation of the Sr system with other...

Cavity-enhanced direct frequency comb spectroscopy is used to obtain simultaneously high resolution and broad spectral-bandwidth measurements of a supersonically cooled jet of acetylene molecules. We demonstrate a complete spatial mapping of density, velocity, and internal state distributions of a cold molecular jet via tomographic reconstructions....

Starting with a near quantum degenerate gas of $^{40}$K and $^{87}$Rb atoms, we create an ultracold dense gas of weakly bound KRb molecules near a magnetic-field tunable Feshbach resonance. These Feshbach molecules have a binding energy of 300 kHz and a density of $10^{12}/\textrm{cm}^3$. We plan to transfer these molecules to more deeply bound sta...

We present experimental efforts toward the creation of ultracold gas of KRb polar molecules. We start by creating extremely weakly bound molecules using a magnetic-field Feshbach resonance. This ultracold dense sample of Feshbach molecules provides a starting point for coherent optical transfer schemes aimed at creating tightly bound, polar molecul...

The absolute frequency of the 1S0-3P0 clock transition of 87Sr has been measured to be 429 228 004 229 873.65 (37) Hz using lattice-confined atoms, where the fractional uncertainty of 8.6x10-16 represents one of the most accurate measurements of an atomic transition frequency to date. After a detailed study of systematic effects, which reduced the...

Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequencies. Rigorous evaluations of these clocks require direct comparisons between them. We have realized a high-performance remote comparison of optical clocks over kilometer-scale urban distances, a key step for development, disseminat...

The phase coherence of an ultrastable optical frequency reference is fully maintained over actively stabilized fiber networks of lengths exceeding 30 km. For a 7-km link installed in an urban environment, the transfer instability is 6 x 10{-18} at 1 s. The excess phase noise of 0.15 rad, integrated from 8 mHz to 25 MHz, yields a total timing jitter...

Recent results from the JILA 87Sr optical lattice clock are presented. Using the tight confinement of an optical lattice in combination wit a sub-Hz linewidth diode laser we have achieved a pulse-length limited linewidth of 1.8 Hz for the 1S0- 3P0 clock transition. This corresponds to a quality factor of Q ≈ 2.4 x 1014, and is a record for coher...

Results from the JILA optical lattice clock are presented. We report on our development of precision tools for the lattice clock, including a stabilized clock laser with sub-Hz linewidth, fs-comb based technology allowing accurate clock comparison in both the microwave and optical domains, and clock transfer over optical fiber in an urban environme...

Metallic nanoparticles (NP) draw intense scientific interest due to their unique physical properties, which differ from those of bulk and atomic species. Nowadays, the aim of this research area is focused, for example, in the nonlinear (NL) optical properties of NP, the dynamics of confined electrons and the possibility of photonic applications. In...

Ultrafast light-induced dichroism in silver nanoparticles is studied. Two differently prepared colloids are examined: one sample has a broad distribution of sizes and shapes of silver nanoparticles, while the second sample, which is processed by laser ablation, presents a more uniform size and shape distribution (greater fraction of spherical parti...

Nonlinear refraction, nonlinear absorption and light induced dichroism (LID) were investigated in silver colloids. The third-, fifth-, and seventh-order susceptibility were determined. The ultrafast dynamics of LID and the contribution of surface plasmons were characterized.

Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequencies. Rigorous evaluations of these clocks require direct comparisons between them. We have realized a high-performance remote comparison of optical clocks over kilometer-scale urban distances, a key step for development, disseminat...

Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequencies. Rigorous evaluations of these clocks require direct comparisons between them. We have realized a high-performance remote comparison of optical clocks over km-scale urban distances, a key step for development, dissemination, an...