Photonics Research, 2018, 6 (5): 05000479, Published Online: Dec. 26, 2018
Generation of a continuous-variable quadripartite cluster state multiplexed in the spatial domain Download: 658次
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Fig. 1. Schematic of the underlying principle involved in generating the CV quadripartite spatial-mode Gaussian cluster state. (a) Pump laser drives the multimode OPA to produce entanglement of two spatial modes, HG 01 and HG 10 , within one beam. By performing the transformation U , the multimode entanglement is transformed into a cluster state containing four spatial orthogonal modes, HG 01 , HG 10 , HG 45 ° , and HG 135 ° . (b) Square representation in the graph-state picture. Each cluster node, corresponding to a spatial mode, is represented by a circle. Neighboring nodes are connected by lines and represent the bipartite entanglement between two spatial modes.
Fig. 2. Experimental layout for the generation and characterization of the spatial-mode cluster state. Entanglement is generated using a multimode OPA and measured by BHD detection with spatial tailored local oscillators. LG 1 0 pump reconstruction is shown in the right panel. NOPA: nondegenerate optical parametric amplifier; LO: local oscillator; DBS: dichroic beam splitter; PBS: polarization beam splitter; HWP: half-wavelength plate; QWP: quarter-wave plate; BHD: balanced homodyne detection; DP: Dove prism; SA: spectrum analyzer; FQ-PM: four-quadrant phase mask; MC: HG 11 − LG 1 0 mode converter.
Fig. 3. Measured quantum correlations of the cluster state in the mode basis (a) HG 01 , (b) HG 10 , (c) HG 45 ° , and (d) HG 135 ° using the fundamental mode pump. Trace (2) is the shot noise limit (SNL), and traces (1) and (3) are the correlation variance and anti-correlation variance, respectively, normalized to SNL. Measurement settings: resolution bandwidth 300 kHz, video bandwidth 390 Hz.
Fig. 4. Enhanced entanglement for the (a) HG 01 , (b) HG 10 , (c) HG 45 ° , and (d) HG 135 ° modes with LG 1 0 pumping. Trace (2) is SNL; traces (1) and (3) are the correlation variances normalized to SNL. Measurement settings: resolution bandwidth 300 kHz, video bandwidth 390 Hz.
Chunxiao Cai, Long Ma, Juan Li, Hui Guo, Kui Liu, Hengxin Sun, Rongguo Yang, Jiangrui Gao. Generation of a continuous-variable quadripartite cluster state multiplexed in the spatial domain[J]. Photonics Research, 2018, 6(5): 05000479.