Coherent accumulation in two-level atoms excited by a train of ultrashort pulses

Felinto, D.; Bosco, C. A. C.; Acioli, L. H.; Vianna, S. S.

doi:10.1016/s0030-4018(02)02230-7

Cited by 66 publications

(57 citation statements)

References 23 publications

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“…The density matrix equations were solved using a perturbative expansion in the field to fourth order. With the approximation of impulsive optical excitation during the pulse, followed by free evolution and decay, an iterative procedure was used to determine the state of the atomic system after any number of pulses (17,18). The model includes the fine and hyperfine structure of the 5S, 5P, and 5D states, with the Zeeman substructure averaged for linear polarization.…”

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confidence: 99%

“…However, their work suggests that versatile programmable molecular systems capable of algorithmic assembly into an infinite variety of 2D or three-dimensional (3D) supra-architectures with increasing pattern complexity, shape, molecular diversity, and size could potentially be generated with nucleic acids (10). Although more chemically labile than DNA, natural RNAs offer a richer treasure trove of rigid structural motifs (11)(12)(13)(14) that can be potential modules for supramolecular engineering (15)(16)(17)(18)(19)(20). RNA tectonics (15) refers to the modular character of RNA, which can be decomposed and reassembled to create new RNA nanoscopic architectures.…”

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United Time-Frequency Spectroscopy for Dynamics and Global Structure

Marian

Stowe

Lawall

et al. 2004

Science

265

195

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Ultrashort laser pulses have thus far been used in two distinct modes. In the time domain, the pulses have allowed probing and manipulation of dynamics on a subpicosecond time scale. More recently, phase stabilization has produced optical frequency combs with absolute frequency reference across a broad bandwidth. Here we combine these two applications in a spectroscopic study of rubidium atoms. A wide-bandwidth, phase-stabilized femtosecond laser is used to monitor the real-time dynamic evolution of population transfer. Coherent pulse accumulation and quantum interference effects are observed and well modeled by theory. At the same time, the narrow linewidth of individual comb lines permits a precise and efficient determination of the global energy-level structure, providing a direct connection among the optical, terahertz, and radio-frequency domains. The mechanical action of the optical frequency comb on the atomic sample is explored and controlled, leading to precision spectroscopy with an appreciable reduction in systematic errors.Ultrashort laser pulses have given a remarkably detailed picture of photophysical dynamics. In studies of alkali atoms (1) and diatomics (2) in particular, coherent wave packet motion has been observed and even actively controlled. However, the broad bandwidth of these pulses has prevented a simultaneous high-precision measurement of state energies. At the expense of losing any direct observation or control of coherent dynamics, precision spectroscopy enabled by continuous wave (cw) lasers has been one of the most important fields of modern scientific research, providing the experimental underpinning of quantum mechanics and quantum electrodynamics.This trade-off between the time and frequency domains might seem fundamental, but in fact it results from pulse-to-pulse phase fluctuations in laser operation. The recent introduction of phase-stabilized, widebandwidth frequency combs based on modelocked femtosecond lasers has provided a direct connection between these two domains (3, 4). Many laboratories have constructed frequency combs that establish optical frequency markers directly linked to a microwave or optical standard, covering a variety of spectral intervals. Atomic and molecular structural information can now be probed over a broad spectral range, with vastly improved measurement precision and accuracy enabled by this absolute frequency-based approach (5). One of the direct applications is the development of optical atomic clocks (6-8). To date, however, traditional cw laserbased spectroscopic approaches have been essential to all of these experiments, with frequency combs serving only as reference rulers (9).Here we take advantage of the phasestable femtosecond pulse train to bridge the fields of high-resolution spectroscopy and ultrafast dynamics. This approach of direct frequency comb spectroscopy (DFCS) uses light from a comb of appropriate structure to directly interrogate a multitude of atomic levels and to study time-dependent quantum coherence. DFCS allows time-resol...

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United Time-Frequency Spectroscopy for Dynamics and Global Structure

Marian

Stowe

Lawall

et al. 2004

Science

265

195

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“…Theoretical [25][26][27] and experimental [28,29] analysis in a few level systems have shown that a resonant π-pulse (or generalized π-pulse [11,12]) can be split into trains of fractional π-pulses and can lead to the accumulation of population in a target state for appropriate delays. The main point is * Electronic address: anahit.gogyan@u-bourgogne.fr that weak pulses can then be used preventing detrimental destructive effects such as ionization.…”

Section: Introductionmentioning

confidence: 99%

Shaping coherent excitation of atoms and molecules by a train of ultrashort laser pulses

Gogyan¹,

Guérin²,

Malakyan³

2010

Phys. Rev. A

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We propose a mechanism to produce a superposition of atomic and molecular states by a train of ultrashort laser pulses combined with weak control fields. By adjusting the repetition rate of the pump pulses and the intensity of the coupling laser, one can suppress a transition, while simultaneously enhancing the desired transitions. As an example various superpositions of states of the K2 molecule are shown.

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“…In N-level systems (NLSs), pulse trains can be used to accumulate population in pre-selected levels [1][2][3][4][5][6][7][8][9][10]. This aspect of population control has been studied in particular for population transfer in 2-level systems (2LSs) [1][2][3]9] and in harmonic and anharmonic N-level progressions [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…This aspect of population control has been studied in particular for population transfer in 2-level systems (2LSs) [1][2][3]9] and in harmonic and anharmonic N-level progressions [4][5][6][7][8]. In dipolar systems, this mechanism also covers multiphoton (mp) transitions without intermediate levels, e.g.…”

Section: Introductionmentioning

confidence: 99%