Scalable in operando strain tuning in nanophotonic waveguides enabling three-quantum-dot superradiance


The quest for an integrated quantum optics platform has motivated the field of semiconductor quantum dot research for two decades. Demonstrations of quantum light sources, single photon switches, transistors and spin–photon interfaces have become very advanced. Yet the fundamental problem that every quantum dot is different prevents integration and scaling beyond a few quantum dots. Here, we address this challenge by patterning strain via local phase transitions to selectively tune individual quantum dots that are embedded in a photonic architecture. The patterning is implemented with in operando laser crystallization of a thin HfO2 film ‘sheath’ on the surface of a GaAs waveguide. Using this approach, we tune InAs quantum dot emission energies over the full inhomogeneous distribution with a step size down to the homogeneous linewidth and a spatial resolution better than 1 µm. Using these capabilities, we tune multiple quantum dots into resonance within the same waveguide and demonstrate a quantum interaction via superradiant emission from three quantum dots.

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Fig. 1: Schematic of the energy tuning approach and sample overview.
Fig. 2: QD tuning curves.
Fig. 3: Spatial resolution of QD tuning.
Fig. 4: Superradiant emission from strain-tuned QDs in a photonic crystal waveguide.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Code availability

COMSOL code used to simulate thermal and strain profiles is available from the corresponding author upon request.


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This work was supported by the US Office of Naval Research, the Defense Threat Reduction Agency (grant no. HDTRA1-15-1-0011), and the OSD Quantum Sciences and Engineering Program. A.C.K. acknowledges the support of the American Society for Engineering Education and US Naval Research Laboratory postdoctoral fellowship program. J.T.M. and B.L. acknowledge the support of the NRC Research Associateship Program at the US Naval Research Laboratory.

Author information

J.Q.G. and A.S.B. conceived of the tuning concept. J.Q.G., A.S.B., S.G.C. and D.G. further developed the tuning concept. J.Q.G. performed the QD energy tuning, spectroscopy and photon correlation measurements. M.Z. and J.Q.G. performed the electron diffraction measurements. M.Z. did the finite-element modelling of the thermal and strain profiles. A.C.K. did HfO2 ALD. A.S.B. and M.Y. grew the QDs with MBE. M.K. and C.K. fabricated the structures and measured SEM. J.T.M. and A.S.B. did AFM measurements and analysis. J.Q.G. and B.L. performed basic sample characterization.

Correspondence to Joel Q. Grim.

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Supplementary Information, Supplementary Figs. 1–12, Supplementary references 1–7

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