Atomic entanglement generation with reduced decoherence via four-wave mixing

Abstract

In most proposals for the generation of entanglement in large ensembles of atoms via projective measurements, the interaction with the vacuum is responsible for both the generation of the signal that is detected and the spin depolarization or decoherence. In consequence, one has to usually work in a regime where the information aquisition via detection is sufficiently slow (weak measurement regime) such as not to strongly disturb the system. We propose here a four-wave mixing scheme where, owing to the pumping of the atomic system into a dark state, the polarization of the ensemble is not critically affected by spontaneous emission, thus allowing one to work in a strong measurement regime.

Dephasing Dynamics Accessed by High Harmonic Generation: Determination of Electron–Hole Decoherence of Dirac Fermions

“…While the interplays between distinct transition channels provide unique harmonic sources, the decoherence now can interfere with the release of HHG depending on the scattering nature. − The decoherence time T 2 , i.e., the dephasing time for loss of electron–hole coherence due to the coupling with nonequilibrium dissipation, is of utmost importance for the physics of coherent quantum control, for instance, like quantum information and computing. , In contrast to the population decay T 1 , the measurement of T 2 usually requires highly nontrivial methods, including the four-wave mixing and pump–probe technique, which just remain in the limited and relative time scale. Beyond the pump–probe scheme, it would be timely to suggest an exquisite pathway for an estimation of T 2 on the basis of quantified evidence for the scattering nature, resulting in the dissipation and the relevant dynamic links among underlying physics.…”

Dephasing dynamics accessed by high harmonic generation: Direct determination of quantum decoherence

“…In contrast to the population decay 𝑇 " 36 , the measurement of 𝑇 ! usually requires highly nontrivial methods 37 including the four-wave mixing 38 but only within the relatively limited time scale. Beyond the pump-probe scheme, it would be timely to suggest an exquisite pathway for an estimation of 𝑇 !…”