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SUMMARY:Observation of photon antibunching from a potential SAW-driven sin
 gle-photon source - Tzu-Kan Hsiao\, Cavendish Laboratory\, University of C
 ambridge\, UK
DTSTART:20180207T140000Z
DTEND:20180207T150000Z
UID:TALK100969@talks.cam.ac.uk
CONTACT:Dr Kaveh Delfanazari
DESCRIPTION:Much effort has been made to create single-photon sources [1\,
 2] due to their applications in\, for example\, quantum key distribution a
 nd quantum repeaters. In this research\, we are developing a single-photon
  source driven by a surface acoustic wave (SAW) [3]. Electrons and holes a
 re induced in adjacent regions by surface gates to form an n-i-p junction 
 in an undoped AlGaAs/GaAs/AlGaAs quantum-well structure. A SAW launched by
  a transducer creates a moving electric potential [4] and drags electrons 
 from the induced region of electrons to the region of holes across a 1D ch
 annel defined by side gates and wet-etch. A single-photon source should th
 ereby be created if the 1D channel allows only one electron in each potent
 ial minimum of the SAW to reach the region of holes and recombine before a
 nother electron arrives in the next potential minimum. \n     We have show
 n that a SAW can pump single electrons between two induced regions of elec
 trons [5]\, and our modelling shows that it is should be possible to achie
 ve similar lateral confinement in the n-i-p junction and hence to pump sin
 gle electrons. We have now fabricated an induced lateral n-i-p junction an
 d have observed electroluminescence (EL) from the junction when the source
 -drain bias is below threshold and a SAW is launched from a transducer\, i
 ndicating SAW-driven EL. In addition\, periodic EL peaks with the periodic
 ity of the SAW can be clearly observed in the time-resolved EL measurement
 \, indicating that electrons are periodically injected into the region of 
 holes by the SAW. Besides\, the SAW-driven EL shows a 160 ps recombination
  lifetime\, meaning that it should be possible to make a GHz-repetition-ra
 te single-photon source using this scheme.\n     Finally\, we have done a 
 Hanbury Brown-Twiss experiment to measure the second-order correlation fun
 ction g2(t) of the photons driven by an 1 GHz SAW. The data shows clear ph
 oton antibunching when the average number of electrons in one SAW cycle is
  less than one. Currently\, the lowest g2(0) we have observed in this devi
 ce is 0.55 ± 0.05\, which is very close to the criterion for single-photo
 n emitter g2(0) < 0.5. Now we are working on improving electron confinemen
 t in the SAW potential\, hoping to get better photon antibunching in our d
 evices.\n\nReferences\n\n[1] A. J. Shields et al.\, Nature Photonics 1\, 2
 15 (2007)\n[2] I. Aharonovich et al.\, Nature Photonics 10\, 631 (2016)\n[
 3] C. L. Foden et al.\, Physical Review A 62\, 011803 (2000)\n[4] C. J. B.
  Ford\, Phys. Status Solidi B 254\, 1600658 (2017)\n[5] Y. Chung\, PhD the
 sis\, Cavendish Laboratory\, University of Cambridge (2015)\n
LOCATION:Mott Seminar Room (Mott Building Room 531)\, Cavendish Laboratory
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