Above-Threshold Ionization by an Elliptically Polarized Field: Interplay between Electronic Quantum Trajectories

Measurements of energy-resolved angular distributions of electrons generated in above-threshold ionization of rare gases in a field with elliptical polarization are presented, with emphasis on the high-energy part of the spectra. The data show a second plateau at a specific angle with respect to the large component of the laser field. The results are compared to a calculation based on a strong-field rescattering approximation. This is interpreted in terms of the superposition of quantum trajectories. The second plateau is associated with the interference of electrons that do and that do not rescatter.

Intense Laser-induced Ionization G.G.Paulus et al

Absolute-phase phenomena in photoionization with few-cycle laser pulses

Currently, the shortest laser pulses1 that can be generated in the visible spectrum consist of fewer than two optical cycles (measured at the full-width at half-maximum of the pulse's envelope).
The time variation of the electric ®eld in such a pulse depends on the phase of the carrier frequency with respect to the enveloped the absolute phase. Because intense laser±matter interactions generally depend on the electric ®eld of the pulse, the absolute phase is important for a number of nonlinear processes2±8. But clear evidence of absolute-phase effects has yet to be detected experimentally, largely because of the dif®culty of stabilizing the absolute phase in powerful laser pulses. Here we use a technique that does not require phase stabilization to demonstrate experimentally the in¯uence of the absolute phase of a short laser pulse on the emission of photoelectrons. Atoms are ionized by a short laser pulse, and the photoelectrons are recorded with two opposing detectors in a plane perpendicular to the laser beam.We detect an anticorrelation in the shot-to-shot analysis of the electron yield.

Absolute-phase phenomena in photoionization with few-cycle laser pulses G.G.Paulus et al

Quantum State Transfer Between Matter and Light

We report on the coherent quantum state transfer from a two-level atomic system to a single photon. Entanglement between a single photon (signal) and a two-component ensemble of cold rubidium atoms is used to project the quantum memory element (the atomic ensemble) onto any desired state by measuring the signal in a suitable basis. The atomic qubit is read out by stimulating directional emission of a single photon (idler) from the (entangled) collective state of the ensemble. Faithful atomic memory preparation and readout are verified by the observed correlations between the signal and the idler photons. These results enable implementation of distributed quantum networking.

Quantum State Transfer Between Matter and Light  D. N. Matsukevich and A. Kuzmich