Transferring of Continuous Variable Squeezed States in 20 km Fiber

Abstract

Transferring of a real quantum state in a long-distance channel is an important task in the development of quantum information networks. For greatly suppressing the relative phase fluctuations between the signal beam and the corresponding local oscillator beam, the usual method is to transfer them with time-division and polarization-division multiplexing through the same fiber. But the nonclassical states of light are very sensitive to the channel loss and extra noise, this multiplexing method must bring the extra loss to the quantum state, which may result in the vanishing of its quantum property. Here, we propose and realize a suitable time multiplexing method for the transferring and measurement of nonclassical states. Only the local oscillator beam is chopped into a sequence of light pulses and transmitted through fiber with continuous orthogonal-polarized signal beam. Finally, when the local oscillator pulses are properly time delayed compared to the signal beam, the quantum state can be measured in the time sequences without the influence of extra noise in the fiber. Our work provides a feasible scheme to transfer a quantum state in relative long distance and construct a practical quantum information network in metropolitan region.