No Arabic abstract
Single photon sources with high brightness and subnanosecond lifetimes are key components for quantum technologies. Optical nanoantennas can enhance the emission properties of single quantum emitters, but this approach requires accurate nanoscale positioning of the source at the plasmonic hotspot. Here, we use plasmonic nanoantennas to simultaneously trap single colloidal quantum dots and enhance their photoluminescence. The nano-optical trapping automatically locates the quantum emitter at the nanoantenna hotspot without further processing. Our dedicated nanoantenna design achieves a high trap stiffness of 0.6 fN/nm/mW for quantum dot trapping, together with a relatively low trapping power of 2 mW/$mu$m$^2$. The emission from the nanoantenna-trapped single quantum dot shows 7x increased brightness, 50x reduced blinking, 2x shortened lifetime and a clear antibunching below 0.5 demonstrating true single photon emission. Combining nano-optical tweezers with plasmonic enhancement is a promising route for quantum technologies and spectroscopy of single nano-objects.
We report on the observation of single-photon superradiance from an exciton in a semiconductor quantum dot. The confinement by the quantum dot is strong enough for it to mimic a two-level atom, yet sufficiently weak to ensure superradiance. The electrostatic interaction between the electron and the hole comprising the exciton gives rise to an anharmonic spectrum, which we exploit to prepare the superradiant quantum state deterministically with a laser pulse. We observe a five-fold enhancement of the oscillator strength compared to conventional quantum dots. The enhancement is limited by the base temperature of our cryostat and may lead to oscillator strengths above 1000 from a single quantum emitter at optical frequencies.
Interference of a single photon generated from a single quantum dot is observed between two photon polarization modes. Each emitted single photon has two orthogonal polarization modes associated with the solid-state single photon source, in which two non-degenerate neutral exciton states are involved. The interference between the two modes takes place only under the condition that the emitted photon is free from which-mode information.
We demonstrate a quantum dot single photon source at 900 nm triggered at 300 MHz by a continuous wave telecommunications wavelength laser followed by an electro-optic modulator. The quantum dot is excited by on-chip-generated second harmonic radiation, resonantly enhanced by a GaAs photonic crystal cavity surrounding the InAs quantum dot. Our result suggests a path toward the realization of telecommunications-wavelength-compatible quantum dot single photon sources with speeds exceeding 1 GHz.
Quantum random number generation (QRNG) harnesses the intrinsic randomness of quantum mechanical phenomena. Demonstrations of such processes have, however, been limited to probabilistic sources, for instance, spontaneous parametric down-conversion or faint lasers, which cannot be triggered deterministically. Here, we demonstrate QRNG with a quantum emitter in hexagonal boron nitride; an emerging solid-state quantum source that can generate single photons on demand and operates at room temperature. We achieve true random number generation through the measurement of single photons exiting one of four integrated photonic waveguides, and subsequently, verify the randomness of the sequences in accordance with the National Institute of Standards and Technology benchmark suite. Our results open a new avenue to the fabrication of on-chip deterministic random number generators and other solid-state-based quantum-optical devices.
Scalable quantum photonic architectures demand highly efficient, high-purity single-photon sources, which can be frequency matched via external tuning. We demonstrate a single-photon source based on an InAs quantum dot embedded in a micropillar resonator, which is frequency tunable via externally-applied stress. Our platform combines the advantages of a Bragg micropillar cavity and the piezo-strain-tuning technique enabling single photon spontaneous emission enhancement via the Purcell effect and quantum dot (QD) with tunable wavelength. Our optomechanical platform has been implemented by integration of semiconductor-based QD-micropillars on a piezoelectric substrate. The fabricated device exhibits spontaneous emission enhancement with a Purcell factor of 4.4$pm$0.7 and allows for a pure triggered single-photon generation with $g^{(2)}(0)$ < 0.07 under resonant excitation. A quantum dot emission energy tuning range of 0.75 meV for 27 kV/cm applied to the piezo substrate has been achieved. Our results pave the way towards the scalable implementation of single-photon quantum photonic technologies using optoelectronic devices.