19 research outputs found
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
Design of broadband high-efficiency superconducting-nanowire single photon detectors
In this paper several designs to maximize the absorption efficiency of
superconducting-nanowire single-photon detectors are investigated. Using a
simple optical cavity consisting of a gold mirror and a SiO2 layer, the
absorption efficiency can be boosted to over 97%: this result is confirmed
experimentally by the realization of an NbTiN-based detector having an overall
system detection efficiency of 85% at 1.31 micrometers. Calculations show that
by sandwiching the nanowire between two dielectric Bragg reflectors, unity
absorption (> 99.9%) could be reached at the peak wavelength for optimized
structures. To achieve broadband high efficiency, a different approach is
considered: a waveguide-coupled detector. The calculations performed in this
work show that, by correctly dimensioning the waveguide and the nanowire,
polarization-insensitive detectors absorbing more than 95% of the injected
photons over a wavelength range of several hundred nm can be designed. We
propose a detector design making use of GaN/AlN waveguides, since these
materials allow lattice-matched epitaxial deposition of Nb(Ti)N films and are
transparent on a very wide wavelength range
Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits
Integrated quantum photonics is a promising approach for future practical and
large-scale quantum information processing technologies, with the prospect of
on-chip generation, manipulation and measurement of complex quantum states of
light. The gallium arsenide (GaAs) material system is a promising technology
platform, and has already successfully demonstrated key components including
waveguide integrated single-photon sources and integrated single-photon
detectors. However, quantum circuits capable of manipulating quantum states of
light have so far not been investigated in this material system. Here, we
report GaAs photonic circuits for the manipulation of single-photon and
two-photon states. Two-photon quantum interference with a visibility of 94.9
+/- 1.3% was observed in GaAs directional couplers. Classical and quantum
interference fringes with visibilities of 98.6 +/- 1.3% and 84.4 +/- 1.5%
respectively were demonstrated in Mach-Zehnder interferometers exploiting the
electro-optic Pockels effect. This work paves the way for a fully integrated
quantum technology platform based on the GaAs material system.Comment: 10 pages, 4 figure
A miniaturized 4 K platform for superconducting infrared photon counting detectors
We report on a miniaturized platform for superconducting infrared photon counting detectors. We have implemented a fibre-coupled superconducting nanowire single photon detector in a Stirling/Joule–Thomson platform with a base temperature of 4.2 K. We have verified a cooling power of 4 mW at 4.7 K. We report 20% system detection efficiency at 1310 nm wavelength at a dark count rate of 1 kHz. We have carried out compelling application demonstrations in single photon depth metrology and singlet oxygen luminescence detection
PIZZICATO: Picosecond Scintillator Timing with Superconducting Nanowire Single-Photon Detectors
Time-of-flight positron emission tomography (TOF-PET) visualizes molecular processes in vivo and is commonly used in the treatment of cancer. TOF-PET can be transformed into a tool for personalized medicine in a much wider range of clinical applications if we can improve the time-of-flight resolution to ~10 ps. The PIZZICATO consortium is developing a novel type of TOF-PET detector based on large-area superconducting nanowire single-photon detectors (SNSPD) optically coupled to ultrafast direct-bandgap semiconductor scintillators. Here, we present first proof-of-concept results, including the successful development of large-area SNSPDs with sub-10 ps single-photon time resolution and first measurements of scintillation signals using SNSPDs