THESIS
2018
xiii, 124 pages : illustrations ; 30 cm
Abstract
Photonic entanglement has long been recognized as an important type of entanglement which
serves as a versatile tool for fundamental entanglement research and a building block of quantum
networks. Entangled photon pairs (biphotons) can not only realize faithful entanglement distribution
over long distance, but also interconnect with stationary quantum nodes.
In this Thesis, we present a systematic study of time-frequency entangled biphotons with narrow
bandwidth. We first theoretically analyze photon-atom interaction and discuss some important
nonlinear processes that our work is based on, including electromagnetically induced transparency
(EIT) and spontaneous four-wave mixing (FWM). After describing our experimental systems in
detail, we report generation of narrowband biphoto...[
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Photonic entanglement has long been recognized as an important type of entanglement which
serves as a versatile tool for fundamental entanglement research and a building block of quantum
networks. Entangled photon pairs (biphotons) can not only realize faithful entanglement distribution
over long distance, but also interconnect with stationary quantum nodes.
In this Thesis, we present a systematic study of time-frequency entangled biphotons with narrow
bandwidth. We first theoretically analyze photon-atom interaction and discuss some important
nonlinear processes that our work is based on, including electromagnetically induced transparency
(EIT) and spontaneous four-wave mixing (FWM). After describing our experimental systems in
detail, we report generation of narrowband biphotons from laser-cooled
85Rb atoms and a hot
87Rb
atomic vapor cell. These biphotons are naturally time-frequency entangled because of energy conservation
in the generation process. Working with cold atoms, we can produce high-quality biphotons
with bandwidth down to sub-MHz, and working with the hot atom system we can produce
biphotons with high spectral brightness and high signal contrast ratio.
Although these narrowband biphotons are inherently time-frequency entangled, this continuous
entanglement is difficult to be controlled and studied. Therefore, we create discrete frequency-bin entanglement and confirm the genuine entanglement through the Bell’s inequality test. Such
frequency-bin entangled narrowband biphotons with features of extendable entanglement dimension,
propagation-error resilience and efficient photon-atom interaction are expected to find various
applications in quantum information processing and quantum metrology. At last, we report a single
photon experiment with an atomic beam splitter based on EIT storage. The single photon wave
nature and particle nature are well-preserved in this atomic beam splitter.
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