[show abstract][hide abstract] ABSTRACT: Single-photon detectors (SPDs) at near infrared wavelengths with high system
detection efficiency (> 90%), low dark count rate (< 1 counts per second, cps),
low timing jitter (< 100 ps), and short reset time (< 100 ns) would enable
landmark experiments in a variety of fields. Although some of the existing
approaches to single-photon detection fulfill one or two of the above
specifications, to date no detector has met all of the specifications
simultaneously. Here we report on a fiber-coupled single-photon-detection
system employing superconducting nanowire single photon detectors (SNSPDs) that
closely approaches the ideal performance of SPDs. Our detector system has a
system detection efficiency (SDE), including optical coupling losses, greater
than 90% in the wavelength range \lambda = 1520-1610 nm; device dark count rate
(measured with the device shielded from room-temperature blackbody radiation)
of ~ 0.01 cps; timing jitter of ~ 150 ps FWHM; and reset time of 40 ns.
[show abstract][hide abstract] ABSTRACT: Single-photon sources and detectors are key enabling technologies for photonics in quantum information science and technology (QIST). QIST applications place high-level demands on the performance of sources and detectors; it is therefore essential that their properties can be characterized accurately. Superconducting nanowire single-photon detectors (SNSPDs) have spectral sensitivity from visible to beyond 2 mum in wavelength, picosecond timing resolution (Jitter
[show abstract][hide abstract] ABSTRACT: Advanced quantum information science and technology (QIST) applications place exacting de- mands on optical components. Quantum waveguide circuits offer a route to scalable QIST on a chip. Superconducting single-photon detectors (SSPDs) provide infrared single-photon sensitivity combined with low dark counts and picosecond timing resolution. In this study we bring these two technologies together. Using SSPDs we observe a two-photon interference visibility of 92.3\pm1.0% in a silica-on-silicon waveguide directional coupler at \lamda = 804 nm-higher than that measured with silicon detectors (89.9\pm0.3%). We further operated controlled-NOT gate and quantum metrology circuits with SSPDs. These demonstrations present a clear path to telecom-wavelength quantum waveguide circuits.
[show abstract][hide abstract] ABSTRACT: We report on polarisation correlation from the cascaded recombination of biexcitons in a quantum dot emitting at a telecommunication wavelength. The fine structure splitting of the exciton state in this InAs/GaAs quantum dot is of the order of 100 μeV and polarisation correlation is expected. Strong polarisation correlation between the biexciton and exciton emission lines is observed under both continuous wave (CW) and pulsed laser excitation so telecom wavelength quantum dots with lower energy splittings could be suitable for entangled photon pair generation. Measurements were performed using nanowire superconducting single photon detectors (SSPDs). SSPDs offer low time-jitter and improve the resolution of features in the correlation spectra, including the asymmetric dip and peak resulting from the cascaded emission with the peak extending more than an order of magnitude above the Poissonian level.
Journal of Physics Conference Series 03/2010; 210(1):012036.
[show abstract][hide abstract] ABSTRACT: Superconducting nanowire single-photon detectors (SNSPDs) have emerged as a highly promising infrared single-photon detector technology. Next-generation devices are being developed with enhanced detection efficiency (DE) at key technological wavelengths via the use of optical cavities. Furthermore, new materials and substrates are being explored for improved fabrication versatility, higher DE, and lower dark counts. We report on the practical performance of packaged NbTiN SNSPDs fabricated on oxidized silicon substrates in the wavelength range from 830 to 1700 nm. We exploit constructive interference from the SiO2/Si interface in order to achieve enhanced front-side fiber-coupled DE of 23.2 % at 1310 nm, at 1 kHz dark count rate, with 60 ps full width half maximum timing jitter.
[show abstract][hide abstract] ABSTRACT: We report the first entanglement-based quantum key distribution (QKD) experiment over a 100-km optical fiber. We used superconducting single photon detectors based on NbN nanowires that provide high-speed single photon detection for the 1.5-mum telecom band, an efficient entangled photon pair source that consists of a fiber coupled periodically poled lithium niobate waveguide and ultra low loss filters, and planar lightwave circuit Mach-Zehnder interferometers (MZIs) with ultra stable operation. These characteristics enabled us to perform an entanglement-based QKD experiment over a 100-km optical fiber. In the experiment, which lasted approximately 8 hours, we successfully generated a 16 kbit sifted key with a quantum bit error rate of 6.9 % at a rate of 0.59 bits per second, from which we were able to distill a 3.9 kbit secure key.
[show abstract][hide abstract] ABSTRACT: Quantum key distribution (QKD) has the potential for widespread real-world applications. To date no secure long-distance experiment has demonstrated the truly practical operation needed to move QKD from the laboratory to the real world due largely to limitations in synchronization and poor detector performance. Here we report results obtained using a fully automated, robust QKD system based on the Bennett Brassard 1984 protocol (BB84) with low-noise superconducting nanowire single-photon detectors (SNSPDs) and decoy levels. Secret key is produced with unconditional security over a record 144.3 km of optical fibre, an increase of more than a factor of five compared to the previous record for unconditionally secure key generation in a practical QKD system. Comment: 9 pages
New Journal of Physics 06/2008; · 4.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: We report an entanglement-based BBM92 quantum key distribution experiment using superconducting single photon detectors. A 16-kbit sifted key with a quantum bit error rate of 6.9 % was successfully generated after 100 km fiber transmission.