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arXiv:2607.26957

Two-photon interference from as-grown InAsP/InP quantum dots under detuned excitation

Maja Wasiluk, Anna Musiał, Paweł Mrowiński, Johann Peter Reithmaier, Mohamed Benyoucef, Wojciech Rudno-Rudziński

quant-phcond-mat.mes-hallSubmitted Jul 29, 2026• Announced Jul 30, 2026• 0 citations
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Abstract

In this study, we investigate as-grown InAsP/InP quantum dots emitting in the third telecommunication window under detuned quasi-resonant excitation. A large excitation-emission detuning of 32 meV enables efficient suppression of scattered laser light while retaining several advantages of near-resonant excitation. The single-photon nature of the emission is confirmed by a Hanbury Brown and Twiss experiment, yielding a raw second-order autocorrelation value of $g_{\mathrm{raw}}^{(2)}(0)=0.076(6)$. Hong-Ou-Mandel measurement is used to determine the degree of indistinguishability of single photons and reveal as measured visibilities of $V=0.094(4)$ and $V=0.106(5)$ for excitation pulse separations of 13.1 ns and 5.3 ns, respectively. These results demonstrate the potential of as-grown InAsP/InP quantum dots grown via molecular beam epitaxy under not experimentally demanding detuned excitation for generating indistinguishable telecom single photons. Further improvements are to be achieved through Purcell enhancement in optical cavities.

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Submitted to Nanophotonics

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In this study, we investigate as-grown InAsP/InP quantum dots emitting in the third telecommunication window under detuned quasi-resonant excitation. A large excitation-emission detuning of 32 meV enables efficient suppression of scattered laser light while retaining several advantages of near-resonant excitation. The single-photon nature of the emission is confirmed by a Hanbury Brown and Twiss experiment, yielding a raw second-order autocorrelation value of graw(2)(0)=0.076(6)g_{\mathrm{raw}}^{(2)}(0)=0.076(6)graw(2)​(0)=0.076(6). Hong-Ou-Mandel measurement is used to determine the degree of indistinguishability of single photons and reveal as measured visibilities of V=0.094(4)V=0.094(4)V=0.094(4) and V=0.106(5)V=0.106(5)V=0.106(5) for excitation pulse separations of 13.1 ns and 5.3 ns, respectively. These results demonstrate the potential of as-grown InAsP/InP quantum dots grown via molecular beam epitaxy under not experimentally demanding detuned excitation for generating indistinguishable telecom single photons. Further improvements are to be achieved through Purcell enhancement in optical cavities.
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In this work we present a cavity-enhanced InAs/In0.53Al0.23Ga0.24As\mathrm{In_{0.53}Al_{0.23}Ga_{0.24}As}In0.53​Al0.23​Ga0.24​As quantum dot (QD) single-photon source in the telecom C-band with a record-low biexciton emitter decay time of \SI{67.4(2)}{ps} under resonant two-photon excitation (TPE). We observe strong multiphoton suppression associated with gX(2)(0)=0.006(1)g^{(2)}_\mathrm{X}(0) = 0.006(1)gX(2)​(0)=0.006(1) and gXX(2)(0)=0.007(1)g^{(2)}_\mathrm{XX}(0) = 0.007(1)gXX(2)​(0)=0.007(1) for the exciton (X) and biexciton (XX) emission, respectively. Due to a asymmetric Purcell enhancement of the XX-X cascade, the two-photon interference (TPI) visibility of XX photons under πππ-pulse excitation of VTPI=90(3)%V_{\rm{TPI}} = 90(3)\%VTPI​=90(3)% reaches the theoretical limit and clearly exceeds the ∼60%\sim60\%∼60% expected for standard XX-X cascades without photonic engineering. Furthermore, adding a second timed laser pulse coinciding with XX emission energy, we demonstrate stimulated TPE in the telecom C-Band. The result is an improved TPI visibility of the X photons of VTPI=0.69(3)V_{\rm{TPI}}=0.69(3)VTPI​=0.69(3) compared to TPE with VTPI=0.61(4)V_{\rm{TPI}}=0.61(4)VTPI​=0.61(4), with both being reduced compared to the theoretical values due to present dephasing effects. The advances presented in this work hold important promises for the implementation of advanced schemes of quantum communication using deterministic quantum light sources.