We study the probability for multiphoton absorption processes induced by both laser and thermal light acting on an atomic system. When the thermal radiation, suitably filtered, has the same frequency spectrum and the same total energy as the laser packet, we find that the ratio between the relative probabilities for $s$ -photon absorption can be expressed by ${(4\ensuremath{\pi})}^{\frac{\ensuremath{-}1}{2(s\ensuremath{-}1)}}s!{s}^{\frac{1}{2}}{(\frac{{\ensuremath{\tau}}_{c}}{\ensuremath{\tau}})}^{s\ensuremath{-}1},$ where $\ensuremath{\tau}$ is the time during which the atomic system is illuminated by thermal radiation with coherence time ${\ensuremath{\tau}}_{c}$. This shows that multiphoton absorption processes depend on the statistical properties of the incident light, and that the probability induced by the laser packet is certainly greater than that induced by the thermal light if $s<\frac{\ensuremath{\tau}}{{\ensuremath{\tau}}_{c}}$.We study the probability for multiphoton absorption processes induced by both laser and thermal light acting on an atomic system. When the thermal radiation, suitably filtered, has the same frequency spectrum and the same total energy as the laser packet, we find that the ratio between the relative probabilities for $s$-photon absorption can be expressed by ${(4\ensuremath{\pi})}^{\frac{\ensuremath{-}1}{2(s\ensuremath{-}1)}}s!{s}^{\frac{1}{2}}{(\frac{{\ensuremath{\tau}}_{c}}{\ensuremath{\tau}})}^{s\ensuremath{-}1},$ where $\ensuremath{\tau}$ is the time during which the atomic system is illuminated by thermal radiation with coherence time ${\ensuremath{\tau}}_{c}$. This shows that multiphoton absorption processes depend on the statistical properties of the incident light, and that the probability induced by the laser packet is certainly greater than that induced by the thermal light if $s<\frac{\ensuremath{\tau}}{{\ensuremath{\tau}}_{c}}$.

Physical ReviewJan 25, 196821 citations

Coherence and Interference in Multiphoton Processes

Anna Sanpera, L. Roso

Springer proceedings in physicsJan 1, 19910 citations

Two Photon Resonant Picosecond Pulse Propagation in Lithium Vapor

Anadi Mukherjee

The work of this dissertation has been to prove that the coherence of multiphoton excitation can be studied by an appropriately phased and time delayed sequence of pulses. An application of this fundamental study of coherence has been made for the enhancement of third harmonic generation. The coherent recovery of the energy lost to the two photon absorption process enalled a larger propagation distance for the fundamental than in an interaction which is incoherent or coherent, but not using a 90 degree phase shifted pulse pair. Phase matching over this longer propagation distance gave an enhancement of third harmonic generation.The work of this dissertation has been to prove that the coherence of multiphoton excitation can be studied by an appropriately phased and time delayed sequence of pulses. An application of this fundamental study of coherence has been made for the enhancement of third harmonic generation. The coherent recovery of the energy lost to the two photon absorption process enalled a larger propagation distance for the fundamental than in an interaction which is incoherent or coherent, but not using a 90 degree phase shifted pulse pair. Phase matching over this longer propagation distance gave an enhancement of third harmonic generation.

Aug 1, 19870 citations

Multiphoton absorption by atoms

Bhaskar J. Choudhury

Physics Letters AJul 1, 19740 citations

Suppression of Multiphoton Resonances in Driven Quantum Systems via Pulse Shape Optimization

Denis Gagnon, François Fillion‐Gourdeau, Joey Dumont +2 more

This Letter demonstrates control over multiphoton absorption processes in driven two-level systems, which include, for example, superconducting qubits or laser-irradiated graphene, through spectral shaping of the driving pulse. Starting from calculations based on Floquet theory, we use differential evolution, a general purpose optimization algorithm, to find the Fourier coefficients of the driving function that suppress a given multiphoton resonance in the strong field regime. We show that the suppression of the transition probability is due to the coherent superposition of high-order Fourier harmonics which closes the dynamical gap between the Floquet states of the two-level system.This Letter demonstrates control over multiphoton absorption processes in driven two-level systems, which include, for example, superconducting qubits or laser-irradiated graphene, through spectral shaping of the driving pulse. Starting from calculations based on Floquet theory, we use differential evolution, a general purpose optimization algorithm, to find the Fourier coefficients of the driving function that suppress a given multiphoton resonance in the strong field regime. We show that the suppression of the transition probability is due to the coherent superposition of high-order Fourier harmonics which closes the dynamical gap between the Floquet states of the two-level system.

arXiv:1703.04165Physical Review LettersAug 3, 201717 citations

s

-photon absorption can be expressed by ${(4\ensuremath{\pi})}^{\frac{\ensuremath{-}1}{2(s\ensuremath{-}1)}}s!{s}^{\frac{1}{2}}{(\frac{{\ensuremath{\tau}}_{c}}{\ensuremath{\tau}})}^{s\ensuremath{-}1},$ where $\ensuremath{\tau}$ is the time during which the atomic system is illuminated by thermal radiation with coherence time ${\ensuremath{\tau}}_{c}$. This shows that multiphoton absorption processes depend on the statistical properties of the incident light, and that the probability induced by the laser packet is certainly greater than that induced by the thermal light if $s<\frac{\ensuremath{\tau}}{{\ensuremath{\tau}}_{c}}$.