Experimental long wavelength quantum cryptography: from single-photon transmission to key extraction protocols

We present experiments on long wavelength (lambda = 1.55 mu m) 'plug and pl ay' quantum cryptography systems. We discuss the performance of single-phot on detectors at lambda = 1.55 mu m. Furthermore, we address the full implem entation of the quantum cryptography protocol, discussing in detail the imp lementation of protocols for error correction and privacy amplification nee ded to get a secure key. We illustrate the theory with examples from a full software simulation to show the performance of the complete protocol in te rms of final secure key creation rate.