| The EPR argument raised in1935, reveals that quantum mechanics allows the existence of the non-local correlations between the two spatially separated particles without interaction. Since then, quantum non-local correlation has been investigated both theoretically and experimentally. The quantum entanglement state has become a key resource in the field of quantum information. With the development of quantum information processing, the EPR-type continuous-variable entanglement with big channel capacity to load multiple frequency information should be prepared for the further research on quantum information, thus it may be of significant importance to experimentally generate a broadband EPR-type continuous-variable entanglement with high correlation degrees. Fortunately, it has been demonstrated that non-degenerate optical parametric amplifier (NOPA) made a remarkable enhancement of quantum entanglement. However, it is impossible to realize the entanglement enhancement in the whole frequency region due to the limitation of cavity bandwidth of a NOPA. In this article, we investigate how the cavity bandwidth makes the influence on the entanglement enhancement, which should provide some references for the research on the broadband entanglement enhancement.This article mainly includes,1. Theory calculation has been given about how the cavity bandwidth of NOPA makes the influence on the entanglement enhancement with continuous-variables.2. The noise spectrum of the enhanced entangled state of the NOPA has been experimentally measured on the analysis frequency between2MHz and4MHz, which is reasonable agreement with the theoretically analysis. |
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