Raju Valivarthi

Quantum entanglement is a preliminary requirement for many protocols in quantum computing, communication, and sensing. Entanglement is typically achieved by having two particles created from the same source [1]. However, creating quantum networks and internet requires distributing and manipulating quantum states between remote nodes through protocols such as quantum entanglement. Here we report high-fidelity entanglement swapping using time-bin qubits, with the aim of distributing entanglement between national laboratories in the United States. References: [1] Zhang, W., Xu, D., amp; Chen, L. (2023). Polarization entanglement from parametric down-conversion with an LED pump. Physical Review Applied, 19(5). https://doi.org/10.1103/physrevapplied.19.0540

We have performed Bell state measurements with time-bin qubits encoded into attenuated laser pulses using SNSPDs. Their short recovery time allows not only projections onto |?-> but also onto |?+> Bell states. Together with their high quantum efficiency, around 80% this yields an 60-fold improvement in the efficiency of BSMs with time-bin qubits compared to standard InGaAs detectors. Our results have an impact on quantum repeaters and measurement device independent QKD.