Time-bin entanglement at telecom wavelengths from a hybrid photonic integrated circuit
Hannah Thiel, Lennart Jehle, Robert J. Chapman, Stefan Frick, Hauke Conradi, Moritz Kleinert, Holger Suchomel, M. Kamp, Sven Höfling, Christian Schneider, Norbert Keil, Gregor Weihs
Abstract
Abstract Mass-deployable implementations for quantum communication require compact, reliable, and low-cost hardware solutions for photon generation, control and analysis. We present a fiber-pigtailed hybrid photonic circuit comprising nonlinear waveguides for photon-pair generation and a polymer interposer reaching $${68}\,\hbox {dB}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>68</mml:mn> <mml:mspace/> <mml:mtext>dB</mml:mtext> </mml:mrow> </mml:math> of pump suppression and photon separation based on a polarizing beam splitter with $$>{25}\,\hbox {dB}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>></mml:mo> <mml:mn>25</mml:mn> <mml:mspace/> <mml:mtext>dB</mml:mtext> </mml:mrow> </mml:math> polarization extinction ratio. The optical stability of the hybrid assembly enhances the quality of the entanglement, and the efficient background suppression and photon routing further reduce accidental coincidences. We thus achieve a $$\left( 96_{-8}^{+3}\right) \%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mfenced> <mml:msubsup> <mml:mn>96</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>8</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msubsup> </mml:mfenced> <mml:mo>%</mml:mo> </mml:mrow> </mml:math> concurrence and a $$\left( 96_{-5}^{+2}\right) \%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mfenced> <mml:msubsup> <mml:mn>96</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> </mml:mfenced> <mml:mo>%</mml:mo> </mml:mrow> </mml:math> fidelity to a Bell state. The generated telecom-wavelength, time-bin entangled photon pairs are ideally suited for distributing Bell pairs over fiber networks with low dispersion.