One Photon At A Time...

The single-photon detector is characterized by five convincing factors: 91% detection efficiency; direct integration on chip; counting rates on a Gigahertz scale; high timing resolution and negligible dark counting rates. Source: KIT/CFN.

Ultrafast, efficient, and reliable single-photon detectors are among the most sought-after components in photonics and quantum communication, which have not yet reached maturity for practical application. Physicist Dr. Wolfram Pernice of the Karlsruhe Institute of Technology (KIT), in cooperation with colleagues at Yale University, Boston University, and Moscow State Pedagogical University, achieved the decisive breakthrough by integrating single-photon detectors with nanophotonic chips. The detector combines near-unity detection efficiency with high timing resolution and has a very low error rate. The results have been published by Nature Communications (doi:10.1038/ncomms2307).

Without reliable detection of single photons, it is impossible to make real use of the latest advances in optical data transmission or quantum computation; it is like having no analog-digital converter in a conventional computer to determine whether the applied voltage stands for 0 or 1. Although a number of different single-photon detector models have been developed over the past few years, thus far, none have provided satisfactory performance. 

Several new ideas and advanced developments went into the prototype developed within the “Integrated Quantum Photonics” project at the DFG Center of Functional Nanostructures (CFN). The new single-photon detector, tested in the telecommunications wavelength range, achieves a previously unattained detection efficiency of 91%.

Karlsruhe Institute of Technology:
Quantum Communication: Each Photon Counts, Press Release