Zhao Tian-Ming, Ihn Yong Sup, Kim Yoon-Ho
Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea.
Phys Rev Lett. 2019 Mar 29;122(12):123607. doi: 10.1103/PhysRevLett.122.123607.
In quantum communication and photonic quantum information processing, the requirement of quantum repeaters and quantum memory often imposes a strict bandwidth prerequisite for the entangled photons. At the same time, there is ever more increasing demand for entangling more degrees of freedom, i.e., hyperentanglement, for a photon pair. In this Letter, we report the direct generation of narrow-band orbital angular momentum (OAM) and polarization hyperentangled photons from cold atoms. The narrow-band photon pair is naturally entangled in polarization and OAM, in addition to time-frequency, degrees of freedom due to spin and orbital angular momentum conservation conditions in the spontaneous four-wave mixing process in a cold atom ensemble. The narrow-band hyperentangled photon pair source reported here is expected to play important roles in quantum memory-based long-distance quantum communication.
在量子通信和光子量子信息处理中，量子中继器和量子存储器的需求常常对纠缠光子提出严格的带宽先决条件。与此同时，对光子对纠缠更多自由度（即超纠缠）的需求也在不断增加。在本信函中，我们报告了从冷原子直接产生窄带轨道角动量（OAM）和偏振超纠缠光子。由于冷原子系综中自发四波混频过程中的自旋和轨道角动量守恒条件，该窄带光子对除了在时间 - 频率自由度外，还自然地在偏振和OAM上纠缠。这里报道的窄带超纠缠光子对源有望在基于量子存储器的长距离量子通信中发挥重要作用。
