539 research outputs found
Quantum optics with single quantum dot devices
A single radiative transition in a single-quantum emitter results in the emission of a single photon. Single quantum dots are single-quantum emitters with all the requirements to generate single photons at visible and near-infrared wavelengths. It is also possible to generate more than single photons with single quantum dots. In this paper we show that single quantum dots can be used to generate non-classical states of light, from single photons to photon triplets. Advanced solid state structures can be fabricated with single quantum dots as their active region. We also show results obtained on devices based on single quantum dots.Peer Reviewe
Phonon-Assisted Two-Photon Interference from Remote Quantum Emitters
Photonic quantum technologies are on the verge offinding applications in everyday life with quantum cryptography andquantum simulators on the horizon. Extensive research has beencarried out to identify suitable quantum emitters and single epitaxialquantum dots have emerged as near-optimal sources of bright, on-demand, highly indistinguishable single photons and entangledphoton-pairs. In order to build up quantum networks, it is essentialto interface remote quantum emitters. However, this is still anoutstanding challenge, as the quantum states of dissimilar“artificialatoms”have to be prepared on-demand with highfidelity and thegenerated photons have to be made indistinguishable in all possibledegrees of freedom. Here, we overcome this major obstacle and show an unprecedented two-photon interference (visibility of 51±5%) from remote strain-tunable GaAs quantum dots emitting on-demand photon-pairs. We achieve this result by exploiting forthefirst time the full potential of a novel phonon-assisted two-photon excitation scheme, which allows for the generation ofhighly indistinguishable (visibility of 71±9%) entangled photon-pairs (fidelity of 90±2%), enables push-button biexciton statepreparation (fidelity of 80±2%) and outperforms conventional resonant two-photon excitation schemes in terms of robustnessagainst environmental decoherence. Our results mark an important milestone for the practical realization of quantum repeatersand complex multiphoton entanglement experiments involving dissimilar artificial atom
Measurement of g-factor tensor in a quantum dot and disentanglement of exciton spins
We perform polarization-resolved magneto-optical measurements on single InAsP
quantum dots embedded in an InP nanowire. In order to determine all elements of
the electron and hole -factor tensors, we measure in magnetic field with
different orientations. The results of these measurements are in good agreement
with a model based on exchange terms and Zeeman interaction. In our experiment,
polarization analysis delivers a powerful tool that not only significantly
increases the precision of the measurements, but also enables us to probe the
exciton spin state evolution in magnetic fields. We propose a disentangling
scheme of heavy-hole exciton spins enabling a measurement of the electron spin
time
Two-photon interference from two blinking quantum emitters
We investigate the effect of blinking on the two-photon interference
measurement from two independent quantum emitters. We find that blinking
significantly alters the statistics in the second-order intensity correlation
function g and the outcome of two-photon interference
measurements performed with independent quantum emitters. We theoretically
demonstrate that the presence of blinking can be experimentally recognized by a
deviation from the g value when distinguishable photons
impinge on a beam splitter. Our results show that blinking imposes a mandatory
cross-check measurement to correctly estimate the degree of
indistinguishablility of photons emitted by independent quantum emitters
Quantum Nature of Light Measured With a Single Detector
We realized the most fundamental quantum optical experiment to prove the
non-classical character of light: Only a single quantum emitter and a single
superconducting nanowire detector were used. A particular appeal of our
experiment is its elegance and simplicity. Yet its results unambiguously
enforce a quantum theory for light. Previous experiments relied on more complex
setups, such as the Hanbury-Brown-Twiss configuration, where a beam splitter
directs light to two photodetectors, giving the false impression that the beam
splitter is required. Our work results in a major simplification of the widely
used photon-correlation techniques with applications ranging from quantum
information processing to single-molecule detection.Comment: 7 page
- …