Large-Area Superconducting Nanowire Single-Photon Detectors for Operation at Wavelengths up to 7.4 µm.

The optimization of superconducting thin-films has pushed the sensitivity of superconducting nanowire single-photon detectors (SNSPDs) to the mid-infrared (mid-IR). Earlier demonstrations have shown that straight tungsten silicide nanowires can achieve unity internal detection efficiency (IDE) up to λ = 10 µm. For a high system detection efficiency (SDE), the active area needs to be increased, but material nonuniformity and nanofabrication-induced constrictions make mid-IR large-area meanders challenging to yield. In this work, we improve the sensitivity of superconducting materials and optimize a high-resolution nanofabrication process to demonstrate large-area SNSPDs with unity IDE at 7.4 µm. Our approach yields large-area meanders down to 50 nm width, with average line-width roughness below 10%, and with a lower impact from constrictions compared to previous demonstrations. Our methods pave the way to high-efficiency SNSPDs in the mid-IR band with potential impacts on astronomy, imaging, and physical chemistry.

Phonon counting and intensity interferometry of a nanomechanical resonator.

In optics, the ability to measure individual quanta of light (photons) enables a great many applications, ranging from dynamic imaging within living organisms to secure quantum communication. Pioneering photon counting experiments, such as the intensity interferometry performed by Hanbury Brown and Twiss to measure the angular width of visible stars, have played a critical role in our understanding of the full quantum nature of light. As with matter at the atomic scale, the laws of quantum mechanics also govern the properties of macroscopic mechanical objects, providing fundamental quantum limits to the sensitivity of mechanical sensors and transducers. Current research in cavity optomechanics seeks to use light to explore the quantum properties of mechanical systems ranging in size from kilogram-mass mirrors to nanoscale membranes, as well as to develop technologies for precision sensing and quantum information processing. Here we use an optical probe and single-photon detection to study the acoustic emission and absorption processes in a silicon nanomechanical resonator, and perform a measurement similar to that used by Hanbury Brown and Twiss to measure correlations in the emitted phonons as the resonator undergoes a parametric instability formally equivalent to that of a laser. Owing to the cavity-enhanced coupling of light with mechanical motion, this effective phonon counting technique has a noise equivalent phonon sensitivity of 0.89 ± 0.05. With straightforward improvements to this method, a variety of quantum state engineering tasks using mesoscopic mechanical resonators would be enabled, including the generation and heralding of single-phonon Fock states and the quantum entanglement of remote mechanical elements.

Demonstration of a Thermally Coupled Row-Column SNSPD Imaging Array.

While single-pixel superconducting nanowire single photon detectors (SNSPDs) have demonstrated remarkable efficiency and timing performance from the UV to near-IR, scaling these devices to large imaging arrays remains challenging. Here, we propose a new SNSPD multiplexing system using thermal coupling and detection correlations between two photosensitive layers of an array. Using this architecture with the channels of one layer oriented in rows and the second layer in columns, we demonstrate imaging capability in 16-pixel arrays with accurate spot tracking at the few-photon level. We also explore the performance trade-offs of orienting the top layer nanowires parallel and perpendicular to the bottom layer. The thermally coupled row-column scheme is readily able to scale to the kilopixel size with existing readout systems and, when combined with other multiplexing architectures, has the potential to enable megapixel scale SNSPD imaging arrays.

Resolving Photon Numbers Using a Superconducting Nanowire with Impedance-Matching Taper.

Time- and number-resolved photon detection is crucial for quantum information processing. Existing photon-number-resolving (PNR) detectors usually suffer from limited timing and dark-count performance or require complex fabrication and operation. Here, we demonstrate a PNR detector at telecommunication wavelengths based on a single superconducting nanowire with an integrated impedance-matching taper. The taper provides a kΩ load impedance to the nanowire, making the detector's output amplitude sensitive to the number of photon-induced hotspots. The prototyping device was able to resolve up to four absorbed photons with 16.1 ps timing jitter and <2 c.p.s. device dark count rate. Its exceptional distinction between single- and two-photon responses is ideal for high-fidelity coincidence counting and allowed us to directly observe bunching of photon pairs from a single output port of a Hong-Ou-Mandel interferometer. This detector architecture may provide a practical solution to applications that require high timing resolution and few-photon discrimination.

Kilopixel array of superconducting nanowire single-photon detectors.

We present a 1024-element near-infrared imaging array of superconducting nanowire single photon detectors (SNSPDs) using a 32×32 row-column multiplexing architecture. The array has an active area of 0.96 × 0.96 mm, making it the largest SNSPD array reported to date in terms of both active area and pixel count. Using a 64-channel time-tagging readout, we have characterized the array's yield, efficiency, and timing resolution. Large arrays of SNSPDs are desirable for applications such as imaging, spectroscopy, or particle detection.

Optically Addressing Single Rare-Earth Ions in a Nanophotonic Cavity.

We demonstrate optical probing of spectrally resolved single Nd^{3+} rare-earth ions in yttrium orthovanadate. The ions are coupled to a photonic crystal resonator and show strong enhancement of the optical emission rate via the Purcell effect, resulting in near radiatively limited single photon emission. The measured high coupling cooperativity between a single photon and the ion allows for the observation of coherent optical Rabi oscillations. This could enable optically controlled spin qubits, quantum logic gates, and spin-photon interfaces for future quantum networks.

High-efficiency WSi superconducting nanowire single-photon detectors for quantum state engineering in the near infrared.

We report on high-efficiency superconducting nanowire single-photon detectors based on amorphous tungsten silicide and optimized at 1064 nm. At an operating temperature of 1.8 K, we demonstrated a 93% system detection efficiency at this wavelength with a dark noise of a few counts per second. Combined with cavity-enhanced spontaneous parametric downconversion, this fiber-coupled detector enabled us to generate narrowband single photons with a heralding efficiency greater than 90% and a high spectral brightness of 0.6×104 photons/(s·mW·MHz). Beyond single-photon generation at large rate, such high-efficiency detectors open the path to efficient multiple-photon heralding and complex quantum state engineering.

Strong Loophole-Free Test of Local Realism.

We present a loophole-free violation of local realism using entangled photon pairs. We ensure that all relevant events in our Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high-speed polarization measurements. A high-quality polarization-entangled source of photons, combined with high-efficiency, low-noise, single-photon detectors, allows us to make measurements without requiring any fair-sampling assumptions. Using a hypothesis test, we compute p values as small as 5.9×10^{-9} for our Bell violation while maintaining the spacelike separation of our events. We estimate the degree to which a local realistic system could predict our measurement choices. Accounting for this predictability, our smallest adjusted p value is 2.3×10^{-7}. We therefore reject the hypothesis that local realism governs our experiment.

Extraction of plate bending stiffness from coincidence angles of sound transmission measurements.

The bending stiffness in a homogeneous, isotropic, thin plate is experimentally derived from measurements of coincidence angles extracted from supercritical sound transmission versus frequency measurements. A computer controlled turn table rotates a plate sample and a receiver array, placed in the near field of the plate. The array is used to track the transmitted sound through the plate, generated by a far-field stationary source, using beam forming. The array technique enables measurement of plates measuring only one wavelength in width. Two examples are used for proof of concept, including an aluminum plate in air and an alumina plate under water.

On the measurement of airborne, angular-dependent sound transmission through supercritical bars.

The coincidence effect is manifested by maximal sound transmission at angles at which trace wave number matching occurs. Coincidence effect theory is well-defined for unbounded thin plates using plane-wave excitation. However, experimental results for finite bars are known to diverge from theory near grazing angles. Prior experimental work has focused on pulse excitation. An experimental setup has been developed to observe coincidence using continuous- wave excitation and phased-array methods. Experimental results with an aluminum bar exhibit maxima at the predicted angles, showing that coincidence is observable using continuous waves. Transmission near grazing angles is seen to diverge from infinite plate theory.

Review of the genera Berlesia Canestrini, 1884, and Katydiseius Fain amp; Lukoschus, 1983, the subfamily Katydiseiinae Fain amp; Lukoschus, 1983, and their family group relationships (Acari: Mesostigmata: Gamasina), with description of three new species parasitic on gryllacridid crickets (Orthoptera).

The gamasine genus Berlesia Canestrini, 1884, is revived and further diagnosed, based on descriptions of adult females, males and nymphs of three new species (B. hospitabilis sp. nov., B. multisetosa sp. nov., B. vorontsovi sp. nov.) ectoparasitic on raspy crickets of three genera of Gryllacrididae (Ensifera) from Australia and the Philippines. A tight sister relationship of Berlesia with the monobasic genus Katydiseius Fain Lukoschus, 1983, known only from a pseudophylline katydid in Malaysia, is proposed. The subfamily Katydiseiinae Fain Lukoschus, 1983 (previously included in the family Otopheidomenidae in the superfamily Phytoseioidea) is redefined to include only those two genera, and moved to the dermanyssoid family Laelapidae, while its previously other monobasic genus, Eickwortius Zhang, 1995, is retained tentatively in the family Otopheidomenidae. Among other taxa relevant to Katydiseiinae reviewed here, Berlesia cultrigera Berlese, 1910a is transferred to the genus Orthopteroseius Mo, 1996, at present Otopheidomenidae, as Orthopteroseius cultrigerum (Berlese) comb. nov., and Berlesia nuda Berlese, 1910b is transferred to the genus Prasadiseius Wainstein, 1972, at present Otopheidomenidae, as Prasadiseius nudum (Berlese) comb. nov. A key to the two genera and five species recognized as belonging in Katydiseiinae is presented. Notable morphological traits of Berlesia, including only deutonymphs equipped with well-developed claws and males with dimorphically more elongated salivary stylets, are discussed. The one known life cycle of a species of Berlesia, B. hospitabilis sp. nov., includes protonymphipary, followed by a fully functioning deutonymph, and male copulation with pharate females-traits, rarely or not known among gamasine mite associates of invertebrates. The possible significance of elongate spermatodactyls and male reduced feeding are explored.

Catalogue of New Zealand land, freshwater and estuarine molluscan taxa named by Frederick Wollaston Hutton between 1879 and 1904.

Details are provided on 16 land snail genera, eight freshwater molluscan species, one estuarine species, 47 land snail species and varieties from New Zealand, and a further three land snail species putatively from New Zealand, which were described by Frederick Wollaston Hutton between 1879 and 1904. Original primary type material of 54 species was located during the present study. Lectotypes are designated for: Amphidoxa cornea Hutton, 1882, Amphidoxa jacquenetta Hutton, 1883, Amphidoxa perdita Hutton, 1883, Charopa cassandra Hutton, 1883, Cyclotus charmian Hutton, 1883, Fruticicola adriana Hutton, 1883, Gerontia cordelia Hutton, 1883, Gerontia pantherina Hutton, 1882, Microphysa pumila Hutton, 1882, Patula jessica Hutton, 1883, Patula lucetta Hutton, 1884, Patula sylvia Hutton, 1883, Patula tapirina Hutton, 1882, Pfeifferia cressida Hutton, 1883, Phrixgnathus celia Hutton, 1883, Phrixgnathus haasti Hutton, 1883, Phrixgnathus marginatus Hutton, 1882, Phrixgnathus phrynia Hutton, 1883, Rhytida australis Hutton, 1882, Strobila leiodon Hutton, 1882, Thalassia propinqua Hutton, 1882, Therasia thaisa Hutton, 1883, Therasia valeria Hutton, 1883 and Zonites helmsii Hutton, 1882. A neotype is designated for Rhytida citrina Hutton, 1882. Primary type material of the following taxa is figured herein for the first time: Amphidoxa lavinia Hutton, 1883, Cyclotus charmian Hutton, 1883, Fruticicola adriana Hutton, 1883, Leptopoma pannosa Hutton, 1882, Patula lucetta Hutton, 1884, Patula sylvia Hutton, 1883, Patula tapirina Hutton, 1882, Phacussa helmsi var. maculata Hutton, 1884, Phrixgnathus ariel Hutton, 1883, Phrixgnathus celia Hutton, 1883, Rhytida australis Hutton, 1882, Rissoa vana Hutton, 1873, Testacella vagans Hutton, 1882, Trochomorpha hermia Hutton, 1883 and Zonites helmsii Hutton, 1882. New taxonomic combinations introduced herein include Phacussa lucetta (Hutton, 1884) and Therasia propinqua (Hutton, 1882). Amphidoxa lavinia Hutton, 1883, Charopa cassandra Hutton, 1883, Patula timandra Hutton, 1883 and Trochomorpha hermia Hutton, 1883 are treated as junior synonyms of Tasmaphena sinclairii (Pfeiffer, 1846), Phacussa fulminata (Hutton, 1882), Fectola infecta (Reeve, 1852) and Advena campbellii (Gray, 1834), respectively.

Photonic Readout of Superconducting Nanowire Single Photon Counting Detectors.

Scalable, low power, high speed data transfer between cryogenic (0.1-4 K) and room temperature environments is essential for the realization of practical, large-scale systems based on superconducting technologies. A promising approach to overcome the limitations of conventional wire-based readout is the use of optical fiber communication. Optical fiber presents a 100-1,000x lower heat load than conventional electrical wiring, relaxing the requirements for thermal anchoring, and is also immune to electromagnetic interference, which allows routing of sensitive signals with improved robustness to noise and crosstalk. Most importantly, optical fibers allow for very high bandwidth densities (in the Tbps/mm2 range) by carrying multiple signals through the same physical fiber (Wavelength Division Multiplexing, WDM). Here, we demonstrate for the first time optical readout of a superconducting nanowire single-photon detector (SNSPD) directly coupled to a CMOS photonic modulator, without the need for an interfacing device. By operating the modulator in the forward bias regime at a temperature of 3.6 K, we achieve very high modulation efficiency (1,000-10,000 pm/V) and a low input impedance of 500 Ω with a low power dissipation of 40 µW. This allows us to obtain optical modulation with the low, millivolt-level signal generated by the SNSPD.

Nanophotonic rare-earth quantum memory with optically controlled retrieval.

Optical quantum memories are essential elements in quantum networks for long-distance distribution of quantum entanglement. Scalable development of quantum network nodes requires on-chip qubit storage functionality with control of the readout time. We demonstrate a high-fidelity nanophotonic quantum memory based on a mesoscopic neodymium ensemble coupled to a photonic crystal cavity. The nanocavity enables >95% spin polarization for efficient initialization of the atomic frequency comb memory and time bin-selective readout through an enhanced optical Stark shift of the comb frequencies. Our solid-state memory is integrable with other chip-scale photon source and detector devices for multiplexed quantum and classical information processing at the network nodes.

Evidence of a spotted fever-like rickettsia and a potential new vector from northeastern Australia.

A spotted fever-like rickettsia was identified in a Hemaphysalis tick by polymerase chain reaction (PCR) amplification and sequencing of the 16S rDNA, ompA, and ompB genes. A comparison of these nucleotide sequences with those of other spotted fever group (SFG) rickettsiae revealed that the Hemaphysalis tick rickettsia ia was distinct from other previously reported strains. Phylogenetic analysis based on both ompA and ompB also indicates that the strain's closest relatives are the agents of Thai tick typhus (Rickettsia honei strain TT-118) and Flinders Island spotted fever (R. honei). This study represents the first report of an R. honei-like agent from a Hemaphysalis tick in Australia and of a spotted fever group rickettsia from Cape York Peninsula, Queensland.

Haemolaelaps Berlese removed from synonomy with Androlaelaps Berlese (Acari: Laelapidae) .

Comparison of species of Androlaelaps with all members of the Haemolaelaps marsupialis group show these to be two consistently distinct groups. Haemolaelaps is removed from synonomy with Androlaelaps and rediagnosed. A close relationship between Peramelaelaps Womersley and Haemolaelaps is proposed. 

Ulyxes, a new Australopapuan mite genus associated with arboreal nests (Acari: Laelapidae).

As part of a survey of mammal and bird nests, new species, new male stages, and some feeding observations have been collected from what was formerly called the Androlaelaps ulysses group. As many features of this group are consistently different from Androlaelaps, and also from Haemolaelaps where it was formerly placed, this group is here elevated to Ulyxes new genus, and U. autolycus, U. euryclea, and U. theoclymenus are described as new species. This genus has a broad range of feeding behaviour spanning intranasal parasitism, nidicolous parasitism, and at least one species is a nidicolous predator. Its host range is broad; two new species are shown here to cohabit with parrots while most remaining species associate with mammals. In contrast to the variation in feeding behaviour, Ulyxes spp are associated with a narrow range of nest types, being confined to arboreal nests, usually tree hollows (rarely fallen logs), and on the parrot or mammal hosts that use them. Ulyxes spp show a remarkable variability in male cheliceral development, which assorts according to feeding behaviour. There is a strong contrast between male chelicerae of predatory and parasitic species that has not been previously observed in such a compact dermanyssine genus. Previously male cheliceral morphology was thought to be conservative enough to provide diagnostic characters at suprageneric rank. For systematics, these findings complicate previous attempts to recognise male mouthparts as reliable features marking higher-level natural groups that include dermanyssoid vertebrate parasites. For evolutionary studies, this may be relevant in seeking examples of transitions to, or away from, parasitism.

Flinders Island spotted fever rickettsioses caused by "marmionii" strain of Rickettsia honei, Eastern Australia.

Australia has 4 rickettsial diseases: murine typhus, Queensland tick typhus, Flinders Island spotted fever, and scrub typhus. We describe 7 cases of a rickettsiosis with an acute onset and symptoms of fever (100%), headache (71%), arthralgia (43%), myalgia (43%), cough (43%), maculopapular/petechial rash (43%), nausea (29%), pharyngitis (29%), lymphadenopathy (29%), and eschar (29%). Cases were most prevalent in autumn and from eastern Australia, including Queensland, Tasmania, and South Australia. One patient had a history of tick bite (Haemaphysalis novaeguineae). An isolate shared 99.2%, 99.8%, 99.8%, 99.9%, and 100% homology with the 17 kDa, ompA, gltA, 16S rRNA, and Sca4 genes, respectively, of Rickettsia honei. This Australian rickettsiosis has similar symptoms to Flinders Island spotted fever, and the strain is genetically related to R. honei. It has been designated the "marmionii" strain of R. honei, in honor of Australian physician and scientist Barrie Marmion.