Adiabatically driven frequency conversion towards short extreme-ultraviolet radiation pulses

Abstract

We present an experimental demonstration of sum-frequency generation toward tunable picosecond, broadband radiation pulses in the extreme-ultraviolet regime, supported by adiabatically prepared atomic coherences. We drive a two-photon transition in a dense medium of xenon atoms with a long (nanosecond) pump laser pulse at the Fourier-transform-limited bandwidth and with a wavelength of 225 nm. The frequency of the pump pulse is slightly detuned from exact two-photon resonance. In this configuration, the medium is adiabatically driven by a process of coherent population return. The adiabatic passage process generates a maximal coherent superposition of two quantum states with large energy spacing. An additional, short (picosecond) probe laser pulse at a wavelength of 540 nm beats with the maximal atomic coherence and generates a short (picosecond) signal radiation pulse at 93 nm. As compared to conventional (diabatic) frequency conversion, the adiabatically driven maximal atomic coherence yields enhanced conversion efficiency and significantly enhanced stability.

Detuning-induced stimulated Raman adiabatic passage in atoms with hyperfine structure

“…As in the case of the V subsystem, we find thatḟ 3 = 0 from Eq. (11). However, the natural initial condition for this case is ρ 11 = ρ 22 = 0.5, and hence f 2 = 0 as we see from Eqs.…”

“…For instance, maximum coherence prepared between the two ground states in or double-systems results in high conversion efficiency of the FWM field within one coherence length, which means that the phase matching condition is not required for the efficient FWM processes [5][6][7]. Similarly, large coherence prepared between the ground and highly excited states can lead to the enhancement of FWM processes in the vacuum ultraviolet (VUV) or extreme ultraviolet (XUV) regions [8][9][10][11][12][13][14][15], which is known to be a very difficult task [16][17][18][19].…”

All-optical reversible logic gate via adiabatic population transfer

“…An atom prepared in state |3 will be adiabatically driven by the off-resonant Stokes pulse to the intermediate state |2 and back again. This effect is termed "coherent population return" (CPR) (see [40,41] and refs. therein).…”

A novel technique to achieve atomic macro-coherence as a tool to determine the nature of neutrinos

“…For example techniques like stimulated Raman adiabatic passage (STIRAP) [26] or electromagnetic induced transparency (EIT) [27,28] have proven to be a very valuable tool to steer population distributions, generate coherent superposition of quantum states, or support spectroscopical investigations. More concretely, CPR has been recently used to prepare quantum superposition of states maximising therefore the nonlinear response of a medium [29,30]. In the following we will first briefly describe the basis of CPR.…”