Generation of frequency-tunable squeezed single photons from a single quantum dot

Abstract

We demonstrate the generation of frequency-tunable squeezed single photons from a continuous wave laser-driven single-quantum-dot system using a rigorous theoretical formalism, the so-called polaron master equation theory for accurately incorporating the exciton–phonon coupling. We investigate the squeezing for both resonant and off-resonant excitations and show that even for an appropriate off-resonant excitation, the degree of quadrature squeezing can be equal to or even greater than the maximum value obtained for a resonant excitation due to the increased purity of the quantum dot system. We further demonstrate, without losing the degree of squeezing, the tunability of the central frequency of squeezed photons by adjusting the detuning. We show that the detrimental effects due to the exciton–phonon coupling remain negligible up to the phonon bath temperature of 20 K and become quite appreciable beyond this temperature, particularly at higher phonon cutoff frequencies.