Experimental entanglement generation for quantum key distribution beyond 1 Gbit/s

Abstract

Top-performance sources of photonic entanglement are an indispensable resource for many applications in quantum communication, most notably quantum key distribution. However, up to now, no source has been shown to simultaneously exhibit the high pair-creation rate, broad bandwidth, excellent state fidelity, and low intrinsic loss necessary for gigabit secure key rates. In this work, we present for the first time a source of polarization-entangled photon pairs at telecommunication wavelengths that covers all these needs of real-world quantum-cryptographic applications, thus enabling unprecedented quantum-secure key rates of more than 1 Gbit/s. Our source is designed to optimally exploit state-of-the-art telecommunication equipment and detection systems. Any technological improvement of the latter would result in an even higher rate without modification of the source. We discuss the used wavelength-multiplexing approach, including its potential for multi-user quantum networks and its fundamental limitations. Our source paves the way for high-speed quantum encryption approaching present-day internet bandwidth.

Demonstration of quantum-digital payments

“…These limitations are, however, only technological: quantum communication rates can be improved by using brighter quantum sources, while the verification delay originates from the correction of time-tagging drifts between the two buildings (see Methods). Indeed, brighter sources of entangled photon pairs have already been demonstrated, which could decrease the quantum token transmission time to under a second 46 .…”

Preparing the deployment of quantum key distribution over a classical network infrastructure in Prague

“…The high coincidences in channels 38 and 39 indicate the presence of an idler photon corresponding to the signal photon in channel 19, the pair is originating from the same SPDC event. 9 The coincidences were collected at 10-second intervals.…”

“…Figure 3. The number of coincidences recorded between channel 19 of the DWDM and a range of channels from 35 to 40.The high coincidences in channels 38 and 39 indicate the presence of an idler photon corresponding to the signal photon in channel 19, the pair is originating from the same SPDC event 9. The coincidences were collected at 10-second intervals.…”

Investigating the impact of fast count rates on timing jitter in SNSPDs

“…Put another way, jitter is a measure of how precisely you can measure the time at which a photon was detected. This metric is crucial when determining, for example, how precisely you can measure the fluorescence lifetime 17 of an emitter or how tightly you can pack time-bin encoded data for applications such as QKD 18 and pulse-position modulated optical communications. 19…”