5 research outputs found
Robust excitation of C-band quantum dots for quantum communication
Building a quantum internet requires efficient and reliable quantum hardware,
from photonic sources to quantum repeaters and detectors, ideally operating at
telecommunication wavelengths. Thanks to their high brightness and
single-photon purity, quantum dot (QD) sources hold the promise to achieve high
communication rates for quantum-secured network applications. Furthermore, it
was recently shown that excitation schemes, such as longitudinal acoustic
phonon-assisted (LA) pumping, provide security benefits by scrambling the
coherence between the emitted photon-number states. In this work, we
investigate further advantages of LA-pumped quantum dots with emission in the
telecom C-band as a core hardware component of the quantum internet. We
experimentally demonstrate how varying the pump energy and spectral detuning
with respect to the excitonic transition can improve quantum-secured
communication rates and provide stable emission statistics regardless of
network-environment fluctuations. These findings have significant implications
for general implementations of QD single-photon sources in practical quantum
communication networks
Triggered telecom C-band single-photon source with high brightness, high indistinguishability and sub-GHz spectral linewidth
Long-range, terrestrial quantum networks will require high brightness
single-photon sources emitting in the telecom C-band for maximum transmission
rate. Many applications additionally demand triggered operation with high
indistinguishability and narrow spectral linewidth. This would enable the
efficient implementation of photonic gate operations and photon storage in
quantum memories, as for instance required for a quantum repeater. Especially,
semiconductor quantum dots (QDs) have shown these properties in the
near-infrared regime. However, the simultaneous demonstration of all these
properties in the telecom C-band has been elusive. Here, we present a
coherently (incoherently) optically-pumped narrow-band (0.8 GHz) triggered
single-photon source in the telecom C-band. The source shows simultaneously
high single-photon purity with (),
high two-photon interference visibility of 0.508 (0.664) and high
application-ready rates of 0.75 MHz (1.45 MHz) of polarized photons. The source
is based on a QD coupled to a circular Bragg grating cavity combined with
spectral filtering. Coherent (incoherent) operation is performed via the novel
SUPER scheme (phonon-assisted excitation)
Recommended from our members
Quantum dot-based broadband optical antenna for efficient extraction of single photons in the telecom O-band
Long-distance fiber-based quantum communication relies on efficient non-classical light sources operating at telecommunication wavelengths. Semiconductor quantum dots are promising candidates for on-demand generation of single photons and entangled photon pairs for such applications. However, their brightness is strongly limited due to total internal reflection at the semiconductor/vacuum interface. Here we overcome this limitation using a dielectric antenna structure. The non-classical light source consists of a gallium phosphide solid immersion lens in combination with a quantum dot nanomembrane emitting single photons in the telecom O-band. With this device, the photon extraction is strongly increased in a broad spectral range. A brightness of 17% (numerical aperture of 0.6) is obtained experimentally, with a single photon purity of (2)(0)=0.049±0.02 at saturation power. This brings the practical implementation of quantum communication networks one step closer
Enhancing quantum cryptography with quantum dot single-photon sources
Quantum cryptography harnesses quantum light, in particular single photons,
to provide security guarantees that cannot be reached by classical means. For
each cryptographic task, the security feature of interest is directly related
to the photons' non-classical properties. Quantum dot-based single-photon
sources are remarkable candidates, as they can in principle emit
deterministically, with high brightness and low multiphoton contribution. Here,
we show that these sources provide additional security benefits, thanks to the
tunability of coherence in the emitted photon-number states. Generating either
mixed or coherent states of light allows for enhanced performance of many
quantum cryptography applications. We identify the optimal optical pumping
scheme for the main quantum-cryptographic primitives, and benchmark their
performance with respect to Poisson-distributed sources such as attenuated
laser states and down-conversion sources. The presented results will guide
future developments in solid-state and quantum information science for photon
sources that are tailored to quantum communication tasks.Comment: Main Text 9 pages + Appendix 28 page