Fibre wavelength quantum light sources

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The Cambridge team will develop quantum dot single photon emitters for Quantum Communications. The overall projectaims are to demonstrate the controlled emission of entangled photons from an LED structure emitting at a wavelength of1.55microns. This wavelength is the standard wavelength for fibre communications. Devices operating at this wavelengthwill be required to achieve commercially significant Quantum Communications technologies. However entangled photonsfrom quantum dots at this wavelength have not been demonstrated and there is a significant epitaxy challenge indeveloping this technology.The Cambridge team will develop Indium Arsenide quantum dots grown on Indium Phosphide substrates by MolecularBeam Epitaxy (MBE), complementing and contrasting with the development by Metal Organic Vapour Phase Epitaxy(MOVPE) in Sheffield. To demonstrate single photon emitters at this wavelength is challenging and there is a need toinvestigate the properties of the quantum dots by both techniques to understand how the quantum dots form and whatcontrols the fundamental properties that will generate photon entanglement; including aspects such as the exciton spinsplitting value. The work will build significantly on the prior work carried out at shorter wavelengths in Sheffield, Toshibaand Cavendish laboratories using a different material system. In particular at Sheffield the result of quantum dot structuresdeveloped under an EPSRC Programme Grant will benefit the project strongly since many of the physical properties maybe similar. The demonstration of high quality devices at this wavelength will be a significant milestone in matching QuantumCommunications to the current non-quantum fibre-communications infrastructure.