Phys.org May 13, 2022
Progress in optical quantum information processing is hampered by the low efficiency of the two-qubit quantum gates realized so far. Researchers in Germany demonstrated an optical two-qubit gate with an average efficiency above 40%, thus outperforming the previous record by a factor of almost 4. They accomplished this with electromagnetically induced transparency. Incoming photons are converted into polaritons in highly excited Rydberg state. Any two atoms in such a state have a strong interaction, even at large separations. When two photons enter the resonator, both become polaritons and their Rydberg components interact. When the excitations leave the gas, they become just photons, but ones whose phase has been changed by the Rydberg interaction. A dual-rail scheme converts this change in phase into a change in polarization. Theoretical study suggests that even higher efficiency can be expected in the present platform with further technical improvements. This work opens many new possibilities in optical quantum information processing, in which almost all advanced protocols could profit from high-efficiency gates…read more. Open Access TECHNICAL ARTICLEÂ
Scheme of the gate…Credit: Phys. Rev. X 12, 021035, 11 May 2022Â