Title:Quantum Journal Club: Entanglement of Light-Shift Compensated Atomic SpinWaves with Telecom Light
Speaker: Wei Chang Tsinghua University
Time: 2017-03-09 16:00-2017-03-09 17:00


Entanglement of a 795 nm light polarization qubit and an atomic Rb spin-wave qubit for a storage time of 0.1 s is observed by measuring the violation of Bell’s inequality (S ¼ 2:65  0:12). Long qubit storage times are achieved by pinning the spin wave in a 1064 nm wavelength optical lattice, with a magic-valued magnetic field superposed to eliminate lattice-induced dephasing. Four-wave mixing in a cold Rb gas is employed to perform light qubit conversion between near infrared (795 nm) and telecom (1367 nm) wavelengths, and after propagation in a telecom fiber, to invert the conversion process. Observed Bell inequality violation (S ¼ 2:66  0:09), at 10 ms storage confirms preservation of memory-light entanglement through the two stages of light qubit frequency conversion.