X-ray refractive index of laser-dressed atoms

Abstract

We investigated the complex index of refraction in the x-ray regime of atoms in laser light. The laser (intensity up to 10^13 W/cm^2, wavelength 800nm) modifies the atomic states but, by assumption, does not excite or ionize the atoms in their electronic ground state. Using quantum electrodynamics, we devise an ab initio theory to calculate the dynamic dipole polarizability and the photoabsorption cross section, which are subsequently used to determine the real and imaginary part, respectively, of the refractive index. The interaction with the laser is treated nonperturbatively; the x-ray interaction is described in terms of a one-photon process. We numerically solve the resolvents involved using a single-vector Lanczos algorithm. Finally, we formulate rate equations to copropagate a laser and an x-ray pulse through a gas cell. Our theory is applied to argon. We study the x-ray polarizability and absorption near the argon K edge over a large range of dressing-laser intensities. We find electromagnetically induced transparency (EIT) for x rays on the Ar 1s --> 4p pre-edge resonance. We demonstrate that EIT in Ar allows one to imprint the shape of an ultrafast laser pulse on a broader x-ray pulse (duration 100ps, photon energy 3.2keV). Our work thus opens new opportunities for research with hard x-ray sources.

12 pages, 10 figures, 1 table, RevTeX4, corrected typos

References in corpus (10)

• Storage of light in atomic vapor
• A high-accuracy optical clock via three-level coherence in neutral bosonic ${}^{88}$Sr
• Quantum state-resolved probing of strong-field-ionized xenon atoms using femtosecond high-order harmonic transient absorption spectroscopy
• Electromagnetically induced transparency for x rays
• Theory of x-ray absorption by laser-dressed atoms
• An x-ray probe of laser-aligned molecules
• Non-Hermitian Rayleigh-Schroedinger Perturbation Theory
• Theory of x-ray absorption by laser-aligned symmetric-top molecules
• Strong-field control of x-ray absorption
• Rotational molecular dynamics of laser-manipulated bromotrifluoromethane studied by x-ray absorption

Cited by in corpus (7)

• Impact of hollow-atom formation on coherent x-ray scattering at high intensity
• Transient absorption and reshaping of ultrafast XUV light by laser-dressed helium
• Attosecond pulses at kiloelectronvolt photon energies from high-order harmonic generation with core electrons
• Theory of Auger decay by laser-dressed atoms
• X-ray frequency combs from optically controlled resonance fluorescence
• Rotational molecular dynamics of laser-manipulated bromotrifluoromethane studied by x-ray absorption
• Optical control of an atomic inner-shell x-ray laser