Fast, All-Optical, Zero toπContinuously Controllable Kerr Phase Gate

Large Phase-by-Phase Modulations in Atomic Interfaces

“…This leads to the noteworthy result that the mechanism may work in principle for very weak classical signal (control) field excitations. Thus, in proximity of a steep phase-change, radian-level shifts in the signal phase may in general be obtained at a much reduced interaction strength than it would be required to achieve through typical non-linear cross-phasemodulations [23]. Within our twofold closed-loop interface configuration, steep shifts in fact are largely determined by the combined dynamics of two wave packet envelopes rather than their intensities, as clearly embedded in Eq.…”

“…Electromagnetically induced transparency, e.g., is commonly used in trapped atomic samples to enhance the weak Kerr effect responsible for the photonphoton interaction, namely, through a significant reduction of the photon's propagation speed. Within this context, multilevel atom configurations driven to attain large crossphase-modulation effects have been extensively studied [12][13][14][15][16] and over the years various demonstrations [17][18][19][20] of phase shifts, which may even reach the size of a radian [21][22][23], have been carried out yet at the price of fairly large light intensities. Conversely, this seems to confirm early predictions that large shifts through enhancement of Kerr nonlinearities at low-light levels or even down to the singlephoton level [24,25] are unlikely.…”

Versatile, dynamically balanced low-noise optical-field manipulator using a coherently prepared atomic medium

“…Experimentally, Kerr nonlinear effects arising in an N –type EIT medium [19] and a medium with stored atomic-coherence [20] have been studied for phase control operation in the classical field limit. In a Raman gain medium, a fast, all-optical continuously controllable Kerr nonlinear phase gate was demonstrated recently [21]. In addition, fast digital signal processing based on this controllable Kerr gate operation, all-optical multi-logic gate operations and transistor functionalities using a Kerr phase gate method [22] and high-fidelity fast polarization gate operations have also been demonstrated with record low gate control and switching light powers [23].…”

Polarization-selective optical nonlinearities in cold Rydberg atoms

“…A major drawback, in this case, is the mismatch of group velocities which limits the probe and signal interaction time, placing an upper limit on the order of a small fraction of a radian to the resulting cross-phase shift [6]. Large intensities are required instead to reach appreciable nonlinear modulations using Kerr-EIT-like interactions [7]. To overcome this limit, matched double slow-light pulses with two atomic species [8] have been proposed as well as various other variant schemes including the tripod [9][10][11], N-tripod [12,13], and M [14,15] configurations.…”