• Photonics Research
  • Vol. 11, Issue 7, 1175 (2023)
Kai-Chi Chang1、†,*, Xiang Cheng1、2、†, Murat Can Sarihan1, and Chee Wei Wong1、3
Author Affiliations
  • 1Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory, Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, USA
  • 2e-mail: chengxiang@ucla.edu
  • 3e-mail: cheewei.wong@ucla.edu
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    DOI: 10.1364/PRJ.483570 Cite this Article Set citation alerts
    Kai-Chi Chang, Xiang Cheng, Murat Can Sarihan, Chee Wei Wong. Towards optimum Franson interference recurrence in mode-locked singly-filtered biphoton frequency combs[J]. Photonics Research, 2023, 11(7): 1175 Copy Citation Text show less

    Abstract

    Mode-locked biphoton frequency combs exhibit multiple discrete comblike temporal correlations from the Fourier transform of its phase-coherent frequency spectrum. Both temporal correlation and Franson interferometry are valuable tools for analyzing the joint properties of biphoton frequency combs, and the latter has proven to be essential for testing the fundamental quantum nature, the time-energy entanglement distribution, and the large-alphabet quantum key distributions. However, the Franson recurrence interference visibility in biphoton frequency combs unavoidably experiences a falloff that deteriorates the quality of time-energy entanglement and channel capacity for longer cavity round trips. In this paper, we provide a new method to address this problem towards optimum Franson interference recurrence. We first observe mode-locked temporal oscillations in a 5.03 GHz free-spectral range singly filtered biphoton frequency comb using only commercial detectors. Then, we observe similar falloff trend of time-energy entanglement in 15.15 GHz and 5.03 GHz free-spectral range singly filtered biphoton frequency combs, whereas, the optimum central time-bin accidental-subtracted visibility over 97% for both cavities. Here, we find that by increasing the cavity finesse F, we can enhance the detection probability in temporal correlations and towards optimum Franson interference recurrence in our singly filtered biphoton frequency combs. For the first time, via a higher cavity finesse F of 45.92 with a 15.11 GHz free-spectral range singly filtered biphoton frequency comb, we present an experimental 3.13-fold improvement of the Franson visibility compared to the Franson visibility with a cavity finesse F of 11.14 at the sixth time bin. Near optimum Franson interference recurrence and a time-bin Schmidt number near 16 effective modes in similar free-spectral range cavity are predicted with a finesse F of 200. Our configuration is versatile and robust against changes in cavity parameters that can be designed for various quantum applications, such as high-dimensional time-energy entanglement distributions, high-dimensional quantum key distributions, and wavelength-multiplexed quantum networks.
    KSIcross(τ)=dω2πiNSsinc(ωtcoh/2)e4ω2ln(2)/Δω2eiω(τtcoh/2)1+i1πFsin(πω/ΔΩ)eiπω/ΔΩ.

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    F=ΔΩ2Δωc=πΔωcΔTcavity=πarcsin(11lrt21lrt4)=λQ2L,

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    CSImax(τ)=ηSηI160Tgdτ[(|KSI(cross)(τ)|2)+|KSI(cross)(τnΔTcavity)|2+2|KSI(cross)*(τ)KSI(cross)(τnΔTcavity)|2],

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    CSImin(τ)=ηSηI160Tgdτ[(|KSI(cross)(τ)|2)+|KSI(cross)(τnΔTcavity)|22|KSI(cross)*(τ)KSI(cross)(τnΔTcavity)|2],

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    Vn=exp(nπ/F).

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    Kai-Chi Chang, Xiang Cheng, Murat Can Sarihan, Chee Wei Wong. Towards optimum Franson interference recurrence in mode-locked singly-filtered biphoton frequency combs[J]. Photonics Research, 2023, 11(7): 1175
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