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Photon Supression of the shot noise in a quantum point contact

Photon Supression of the shot noise in a quantum point contact. Eva Zakka Bajjani Julien S é gala Joseph Dufouleur Fabien Portier Patrice Roche Christian Glattli Yong Jin Antonella Cavanna. Nano-electronic group SPEC, CEA Saclay. LPN, CNRS, Marcoussis. Quantum Conductor.

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Photon Supression of the shot noise in a quantum point contact

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  1. Photon Supression of the shot noise in a quantum point contact Eva Zakka Bajjani Julien Ségala Joseph Dufouleur Fabien Portier Patrice Roche Christian Glattli Yong Jin Antonella Cavanna Nano-electronic group SPEC, CEA Saclay LPN, CNRS, Marcoussis

  2. Quantum Conductor Introduction (Bandwidth dn) t • Frequency dependence? • Interplay with quantification of electromagnetic energy?

  3. Outline • Introduction • Conductance and zero frequency shot noise of a single mode conductor • Finite frequency shot noise • From an experimentalist’s point of view • Experimental Set up • Results • Perspectives

  4. The wave packet approach Observation time : Emission time : Number of events : Martin and Landauer (1992) 1 channel conductor I V D Reservoir Reservoir Incoming current : ( i ) ( t ) ( r )

  5. The wave packet approach Observation time : Time scale : Number of events : Martin and Landauer (1992) 1 channel conductor I V D Reservoir Reservoir Due to Fermi statistics the incoming current (I0) is noiseless And due to transmission uncertainty : ( i ) ( t ) ( r )

  6. Probing shorter time scales Central limit obey Gaussian statistic ... New physic for

  7. Finite frequency spectrum Emission of a ‘photon’ Gate Gate V

  8. Finite frequency spectrum Emission of a ‘photon’ Gate Gate V

  9. Experimental requirements  Thermal population of photons negligible Corresponding wavelength ~ 10 cm  propagation effect have to be taken into account Gate Gate V

  10. Coupling to a transmission line Transmitted power: Maximum for Zs≈25 kΩZo=50Ω

  11. First solution: adapt the source impedance to the detection impedance (Diffusive Conductor R≈50Ω) Advantage: good coupling and sensitivity Disadvantage: many modes, impossibility to tune their transmission. Feedback of amplifier? Quantitative agreement with theoretical predictions, with Te=100 mK (Tfridge=40 mK) R. J. Schoelkopf et al. Phys. Rev. Lett. 78 , 3370 (1997).

  12. Second solution: on chip detection Advantage: good coupling to a high impedance (single mode) source Disadvantage: coupling constant and bandwidth unknown Photocurrent Q D(1-D) Onset current 4 times higher than expected E. Onac et al. Phys. Rev. Lett. 96 , 176601 (2006).

  13. Third solution: adapt the detection impedance Quarter wavelength impedance adapatation

  14. Implementation DC Bias Bias T k≈1.4, Zeff≈200Ω

  15. Experimental Set-up 300 K 60 mK 800 mK 4 K Shot Noise V DC Bias Vg Shot Noise Accordable Filters 4-8 GHz

  16. Transmission of the Quantum Point Contact  D1,D2,D3 … (VG)

  17. Excess Noise Power at D=1/2

  18. Excess Noise Power at D=1/2

  19. Threshold versus frequency

  20. Threshold versus frequency

  21. Dependence with transmission

  22. CONCLUSION • We have measured the quantum partition noise of a Quantum Point Contact at finite frequency. • Quantitative agreement of the observed shot-noise power dependence with bias voltage and frequency. • Our method opens the way to cross-correlation measurements probing the statistical properties of the photons emitted by a phase coherent conductor.

  23. Fit with no free paramater, exept coupling

  24. Photon noise =  noise  of electrical noise power quantum conductor ( G ) ZC (detector + filter) R Load = ZC Can the sub-Poissonian (fermionic) statistics of electrons be imprinted on photons? Yes, provided that only one or two mode are transmitted, and excitation voltage is not too high (Beenaker Schomerus 2004)

  25. Room temperature Part

  26. Chaîne de détection 300 K 60 mK 800 mK 4 K Lock-in Generateur de creneaux Vg Lock-in Filtres Accordables 4-8 GHz

  27. Plus concrètement Plasmons bidimensionnels Modèle

  28. Experimental requirements  Thermal population of photons negligible Amplifier noise temperature / frequency as small as possible Conductance of the sample independent of bias voltage up to

  29. Quarter wavelength impedance adapatation → Reflected wave → Perfect transmission perfect matching for given frequency compromise between bandwidth and compensated mismatch

  30. Effet de Chauffage? Ordre de grandeur: Pour Rmesa=200Ω//200Ω, D=1, eV=100μeV, on obtient Telec=100 mK Le facteur thermique est alors de l’ordre de 0.5, et on obtient

  31. Signal attendu • Mesa: -3 dB (estimation à partir des courbes G(vG)) • Couplage ligne 140Ω/70Ω/50Ω : -2dB (mesure sur une boîte ‘vide’) • Attenuation dûe aux câbles: -2 dB (mesures à 4.2K) • Circulateurs: 2 X -0.3 dB (idem) • I inox:- 0.2 dB (idem)

  32. Variation du seuil avec la frequence

  33. Est ce bien du bruit de grenaille quantique?

  34. Effet de Chauffage?

  35. Mesure a differentes frequences

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