Time-delay control of reversible electron spirals using arbitrarily chirped attopulses*

Photoionization through single photon absorption by two synchronized, linearly chirped, counter-rotating circularly polarized, attosecond pulses is known [1] to create reversible spiral patterns in the momentum distribution of the ejected electron when the two pulses have equal but opposite chirp rates. Here we extend this study by demonstrating how this reversible spiral pattern can be controlled by varying the chirp rates as well as the time delay between the pulses [2]. For two synchronized pulses, we find that using arbitrary chirp rates of each attosecond pulses can create a reversible spiral pattern identical to the one produced by equal but opposite chirp rates. Having two pulses with arbitrary chirp rates demonstrates the interference between two electron wavepackets with different full width half maximum (FWHM). By adding a nonzero time delay between the pulses, we find that the reversible spiral pattern can be controlled by using the linear Ramsey spectral phase to manipulate the chirp-induced linear or quadratic spectral phases of the photoelectron. Possible applications of such exquisite manipulation of both linear and quadratic spectral phases include manipulation of the photoelectron wavepacket group delay.