Bell state analyzer for spectrally distinct photons
Navin B. Lingaraju, Hsuan‐Hao Lu, Daniel E. Leaird, Steven B. Estrella, Joseph M. Lukens, Andrew M. Weiner · Optica · 2022
We demonstrate a Bell state analyzer that operates directly on frequency mismatch. Based on electro-optic modulators and Fourier-transform pulse shapers, our quantum frequency processor design implements interleaved Hadamard gates in discrete frequency modes. Experimental tests on entangled-photon inputs reveal fidelities of ∼ 98 % for discriminating between the | Ψ + ⟩ and | Ψ − ⟩ frequency-bin Bell states. Our approach resolves the tension between wavelength-multiplexed state transport and high-fidelity Bell state measurements, which typically require spectral indistinguishability.