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Observation of photon antibunching from a potential SAW-driven single-photon source

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If you have a question about this talk, please contact Dr Kaveh Delfanazari.

Much effort has been made to create single-photon sources [1,2] due to their applications in, for example, quantum key distribution and quantum repeaters. In this research, we are developing a single-photon source driven by a surface acoustic wave (SAW) [3]. Electrons and holes are 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 channel defined by side gates and wet-etch. A single-photon source should thereby be created if the 1D channel allows only one electron in each potential minimum of the SAW to reach the region of holes and recombine before another electron arrives in the next potential minimum. We have shown that a SAW can pump single electrons between two induced regions of electrons [5], and our modelling shows that it is should be possible to achieve similar lateral confinement in the n-i-p junction and hence to pump single electrons. We have now fabricated an induced lateral n-i-p junction and have observed electroluminescence (EL) from the junction when the source-drain bias is below threshold and a SAW is launched from a transducer, indicating SAW -driven EL. In addition, periodic EL peaks with the periodicity 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-rate single-photon source using this scheme. Finally, we have done a Hanbury Brown-Twiss experiment to measure the second-order correlation function g2(t) of the photons driven by an 1 GHz SAW . The data shows clear photon 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 device is 0.55 ± 0.05, which is very close to the criterion for single-photon emitter g2(0) < 0.5. Now we are working on improving electron confinement in the SAW potential, hoping to get better photon antibunching in our devices.


[1] A. J. Shields et al., Nature Photonics 1, 215 (2007) [2] I. Aharonovich et al., Nature Photonics 10, 631 (2016) [3] C. L. Foden et al., Physical Review A 62 , 011803 (2000) [4] C. J. B. Ford, Phys. Status Solidi B 254 , 1600658 (2017) [5] Y. Chung, PhD thesis, Cavendish Laboratory, University of Cambridge (2015)

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