FET-QIPC Project IST-1999-10243Solid State Sources for Single Photons (S4P)I. ABRAMLaboratoire CDP - France Télécom / CNRSBagneux, FRANCEC.D.P. (F) (Coord.) U. Konstanz (D)K.T.H. (S) I.O.T.A. (F) E.N.S. (F) U. Exeter (GB)WHO?Solid State Sources for Single Photons (S4P)WHAT?Design and development of Solid State Light Sourcesthat can deliver truly single photons on demand.Enabling technology for photon-based QIPC systems, such as quantum cryptography.Solid State Sources for Single Photons (S4P)WHY?• Attenuated laser pulses have Poisson statistics.• Truly single photon trainsBetter efficiency and better security.t90 % inactive0 photons(bad efficiency)10 % active 95 %: 1 photon 5 % : 2 or more photons (OK) (security hazards) tSolid State Sources for Single Photons (S4P)HOW?• Isolate a single two-level quantum mechanical dipole(WP1 : IOTA)‚ Collect and channel its photons by CQED (WP2 : UNEXE)ƒ Check operation in realistic cryptography testbeds (WP3 : KTH)CdSe Nanocrystals, InAs quantum dots,NV centers, single molecules,….Micropillars, corrugated metallic surfaces,….PhotonAliceBobWP1 : Single one-photon emittersR6GLangmuir-Blodgett films with R6GNV centers in diamondCore (CdSe)Shell (ZnS, CdS)CdSe nanocrystalsInAs quantum dotsWP1 : Single one-photon emittersCharacterisation of single photon emission : antibunching-50 0 50 100 150 200 250 3000510152025303540 Time interval (ns)eventsSamplePhoton detectorPhoton detectorOptical excitationTime-interval counterWP2 : Microcavity designü Photon emitted in 4π srü Redirection and collection CQEDCollection efficiency β = ImodeItotal Fp = 3 Qλ34π2 V β = 1 FpFp+1 high FpDynamical modification(Purcell effect)WP2 : Microcavity design1 µmGaAsAlAsλ cavityQuantum DotsMicropillarsSurface plasmon modeexcited atomFar-field radiation, photonMetal filmEmission mediated by surface plasmon modeMicrodisks PBG µcavities µcavities with corrugated mirrorsWP2 : Microcavity designA single moleculeA single quantum dotA single color center:Single photon collection by evanescent-field probenano-particletipsilica microsphereconventional FP photonic crystalWP3 : Quantum Cryptography TestbedOpticalFiberC2AAmplPhMLaserAliceFADABobPhotonAliceBobtriggFM FMFMDBPhMFBFLmodFBmodtriggmodAlice’scomputerBob’scomputerPulse from the APDgateFM : Faraday mirrorPhM : phase modulatorA : AttenuatorAmpl : amplificatorFM : Faraday mirrorPhM : phase modulatorA : AttenuatorAmpl : amplificatorC1CTarget benchmarks• Overall quantum efficiency of the sourcein excess of 20 %‚ Photon pair production less than 0.01%ƒ Pulse repetition ratein excess of 100 kbits/s„ Compatibility with fiber transmissionoperating wavelength of 670, 850, 1300 or 1550 nmdepending on system
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