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Single-photon Fourier spectroscopy of excitons and biexcitons in single quantum dots

This study focuses on single-photon Fourier spectroscopy of excitons and biexcitons in single quantum dots, essential for linear optical quantum computing and quantum teleportation. It explores coherence length, lineshape, and linewidth measurements through Fourier spectroscopy techniques. The experiment setup involves a Michelson interferometer and a HBT correlator, discussing the visibility of emitted photons in self-assembled InP quantum dots. Various experiments reveal insights into the dephasing mechanisms, charging effects, and thermal phonon population affecting quantum dot behavior.

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Single-photon Fourier spectroscopy of excitons and biexcitons in single quantum dots

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  1. Single-photonFourierspectroscopyofexcitonsandbiexcitonsinsinglequantumdotsSingle-photonFourierspectroscopyofexcitonsandbiexcitonsinsinglequantumdots Team5 Presenter161120041 黄松涛

  2. Singlephotonsource • Usage: • Linearopticalquantumcomputing • Quantumteleportation • Requirement • Indistinguishabilitytwo-photoninterference(coherent) • Fourier-transformlimit • Lineshape • Linewidth

  3. Spectrum • Lightfield • Thedefinitionofthespectrumofthelightfield • WhereisthetruncatelightfieldFT • The‘dip’isrelatedtothespectrum!

  4. Lineshape • Homogenous • Lifetimebroadening(Lorentzianlineshape) • Collisionalbroadening(Lorentzianlineshape) • Inhomogeneous • Dopplerbroadening(Gaussianlineshape)

  5. Linewidth(Dephasing) • Acriticalparameter–Coherencelength(Linewidth) • --radiativelifetime--puredephasingtime • LinewidthMeasurement • Time-domainSpectroscopy • FWM • Fourierspectroscopy

  6. Dephasing Lossofphasecoherence Inelasticdephasing– inelasticscatteringoftheexciton Lorentzianlineshape Zero-phononline(ZPL) Puredephasing– elasticinteractionwithacousticphonons Non-Lorentzianbroadband

  7. FourierSpectroscopy • ThevisibilityofMichelsoninterferometer- • Withtherelationshipthat wherereferstothenormalizedspectrumdensityfunction • Visibility~Fourierspectroscopy • Highprecision,morerobust

  8. Single-photonFourierspectroscopy CombinationofaMichelsoninterferometer(wavelikefeature)andaHBTcorrelator(particlelikefeature)

  9. Experimentsetup • IntensitywasextractedfromthefilmrecordedinCCD • Backgroundwassubtracted • Fittingtheintensitycurvewithsinusoidalfunctiontoextractthevisibility • Sample:self-assembleInPquantumdots(idealwavelength~690nm) (Sample)

  10. Experimentdiscussion(I) • (a)Typicalsingle-dotspectra(6K) • (b)time-resolvedmeasurement(6K)lifetime~ • (c)Visibilityoftheexcitonemission(6K)Insetshowsphotoncorrelations • Zero-phononlineontopofbroadshoulders • Inelasticdephasingexists!

  11. Experimentdiscussion(II) • (d)Visibilityofthebiexcitonemission(6K)

  12. Experimentdiscussion(III) • MeasurementsinparallelonseveraldotsindifferentT • Variationsincoherencelength • Intrinsicdifferencesinthedephasingmechanisms • Chargingeffects • Fluctuatingchargetraps • Blinking • Spectraldiffusion • Thermalphononpopulation

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