Abstract: Millimetron (official RosKosmos name ”Spectrum-M”) is a part of ambitious program called Spectrum intended to cover the whole electromagnetic spectrum with world class facilities. It is an approved mission included in Russian space program with the launch date in 2017..2019 time frame. The Millimetron satellite has a deployable 12 m diameter antenna with inner solid 4..6 m dish and a rim of petals. The mirror design is largely based on Radioastron mission concept that will be launched in 2009. If the antenna is passively cooled by radiation to open space, it would operate at approx. 50 K surface temperature, due to presence of a deployable three layer radiation screen. As a goal, there is a consideration of active cooling of antenna to 4 K, but this will depend on resources available to the project. Lagrangian libration point L2 considered for Millimetron orbit. There are four groups of scientific instruments envisioned: SVLBI instruments Space-Earth VLBI. It will allow to achieve unprecedented spatial resolution. Millimetron mission will attempt to achieve a mm/submm wave SVLBI. For that purpose, a SVLBI instrument covering selected ALMA bands and a standard VLBI band is envisioned, accompanied by a maser reference oscillator, a data digitizing and memory system, and a high speed data transmission link to ground. The ALMA bands can be extended to cover water lines if detector technology allows. Type of detector – heterodyne. Photometer/polarimeter. Recent progress in direct detector cameras with low spectral resolution, allows to propose a large format (5-10 kPixel) photometer camera on board of Millimetron mission. This camera can cover 0.1 – 2 THz region (with adequate amount of pixels per each subband). Wide band moderate resolution imaging spectrometer. Wide band moderate R = 1000 imaging spectrometer type instrument similar to SPICA SAFARI is planned, taking advantage of large cooled dish. It will cover the adequate spectral range allowable by antenna and will also work below 1 THz, as no ground instrument can have a cold main dish. High resolution spectrometer. For high resolution spectroscopy a heterodyne instrument is proposed, conceptually similar to HIFI on Herschel. This instrument will cover interesting frequency spots in 0.5..4 THz frequency range (using central part of antenna for higher frequency). It is sure that advances in LO and mixer technology will allow this frequency coverage.

Abstract: Optical antennas are an emerging concept in physical optics. Similar to radiowave
and microwave antennas, their purpose is to convert the energy of free propagating radiation to localized energy, and vice versa. Optical antennas exploit the unique properties of metal nanostructures, which behave as strongly coupled plasmas at ptical frequencies. The tutorial provides an account of the historical origins and the basic concepts and parameters associated with optical antennas. It also reviews recent work in the field and discusses areas of application, such as light-emitting devices, photovoltaics, and spectroscopy.

Abstract: The competition of ground state (GS) and excited state (ES) is investigated from the as-grown and thermally annealed 1.3 μm ten-layer p-doped InAs/GaAs quantum dot (QD) lasers. The modal gain competition between GS and ES are measured and analyzed around the ES threshold characteristics. Our results show that two-state competition is more significant in devices with short cavity length operating at high temperature. By comparing the as-grown and annealed devices, we demonstrate enhanced GS and suppressed ES lasing from the QD laser annealed at 600 °C for 15 s.

Abstract: We describe a novel GaAs/AlGaAs double-quantumwell device for the infrared photon detection, called ChargeSensitive Infrared Phototransistor (CSIP). The principle of CSIP detector is the photo-excitation of an intersubband transition in a QW as an charge integrating gate and the signal ampli<ef><ac><81>cation by another QW as a channel with very high gain, which provides us with extremely high responsivity (104 – 106 A/W). It has been demonstrated that the CSIP designed for the mid-infrared wavelength (14.7 μm) has an excellent sensitivity; the noise equivalent power (NEP) of 7 × 10-19 W/ with the quantum effciency of ~ 2%. Advantages of the CSIP against the other highly sensitive detectors are, huge dynamic range of > 106, low output impedance of 103 – 104 Ohms, and relatively high operation temperature (> 2 K). We discuss possible applications of the CSIP to FIR photon detection covering 35 – 60 μm waveband, which is a gap uncovered with presently available photoconductors.

Abstract: We show how the parallel connection of photo-sensitive superconducting nanowires can be used to count the number of photons in an optical pulse, down to the single-photon level. Using this principle we demonstrate photon-number resolving detectors with unprecedented sensitivity and speed at telecommunication wavelengths.

Abstract: The state-of-the-art of the NbN nanowire superconducting single-photon detector technology (SSPD) is presented. The SSPDs exhibit excellent performance at 2 K temperature: 30% quantum efficiency from visible to infrared, negligible dark count rate, single-photon sensitivity up to 5.6 µm. The recent achievements in the development of GHz counting rate devices with photon-number resolving capability is presented.

Abstract: We report our design and fabrication of superconducting nanowire single-photon detectors integrated with gold plasmonic nanostructures, which can enhance the absorption of TM-polarized light, and can enlarge the effective area without sacrificing detector speed.

Abstract: The Atacama Large Millimeter/Sub-millimeter Array (ALMA) requires the development and production of 73 state-of-the-art receivers for the 602-720 GHz range – the ALMA Band 9 cartridges. Development and pre-production of the first 8 cartridges was completed between 2003 and 2008, resulting in a cartridge design that meets the project's challenging requirements. The cartridge design remains essentially unchanged for production, while the production and test processes developed during pre-production have been fine-tuned to address the biggest new challenge for this phase – ramping up production to a rate of 2 cartridges per month over 2009-2012.

Abstract: The underlying physics of the generation and detection of terahertz (THz) waves in gases are described. The THz wave generation process takes place in two steps: asymmetric gas ionization by two-frequency laser fields, followed by interaction of the ionized electron wave packets with the surrounding medium, producing an intense ‘echo' with tunable spectral content. In order to clarify the physical picture at the moment of ionization, the laser–atom interaction is treated through solution of the time-dependent Schrödinger equation, yielding an ab initio understanding of the release of the electron wave packets. The second step, where the electrons interact with the surrounding plasma is treated analytically. The resulting pressure dependence of the THz radiation is explored in detail. The THz wave detection process is shown to be the result of four-wave mixing, leading to analytical expressions of the signal obtained which allow for improved optimization of systems that exploit these effects.

Abstract: This paper presents how photonics associated with new arising detection technologies is able to provide fully integrated instrument for coherent beam combination applied to astrophysical interferometry. The feasibility and operation of on-chip coherent beam combiners has been already demonstrated using various interferometric combination schemes. More recently we proposed a new detection principle aimed at directly sampling and extracting the spectral information of an input signal together with its flux level measurement. The so-called SWIFTS demonstrated concept that stands for Stationary-Wave Integrated Fourier Transform Spectrometer, provides full spectral and spatial information recorded simultaneously thanks to a motionless detecting device. Due to some newly available detection principles considered for the implementation of the SWIFTS concept, some technologies can even provide photo-counting operation that brought a significant extension of the interferometry domain of investigation in astrophysics. The proposed concept is applicable to most of the interferometric instrumental modes including fringe tracking, fast and sensitive detection, Fourier spectral reconstruction and also to manage a large number of incoming beams. The paper presents three practical implementations, two dealing with pair-wise integrated optics beam combinations and the third one with an all-in-one 8 beam combination. In all cases the principles turned into a pair wise baseline coding after proper data processing.

Abstract: SIS junction mixers were developed for SMA 400-520 GHz band. The results show receiver noise temperature around 100 K across the band, with noise contribution from RF loss and IF estimated to be around 50 K and 20K, respectively. Two schemes were used to tune out junction's parasitic capacitance. When a parallel inductor is employed, the input impedance is close to Rn, which facilitates impedance matching between the junction and the waveguide probe. Waveguide probes were designed to achieve a low feed-point impedance to match to the junction resistance. Optimum embedding impedances for lower receiver noise temperature were investigated. Performances of two schemes and composition of receiver noise were also discussed.

Abstract: We have performed a study of how direct detection affects the linearity and hence the calibration of an HEB mixer. Two types of waveguide HEB devices have been used: a 0.8 THz HEB mixer and a 1.0 THz HEB mixer which is ~5 times smaller than the former. Two independent experimental approaches were used. In the ΔG/G method, the conversion gain of the HEB mixer is first measured as a function of the bias current for a number of bias voltages. At each bias setting, we carefully measure the change in the operating current when the input loads are switched. From the measured data, we can derive the expected difference in gain between the hot and cold loads. In the second method (injection method [1]), the linearity of the HEB mixer is independently measured by injecting a modulated signal for different input load temperatures. The results of both approaches confirm that there is gain compression in the operation of HEB mixers. Based on the results of our measurements, we discuss the impact of direct detection effects on the operation of HEB mixers.

Abstract: We present a new photon number resolving detector (PNR), the Parallel Nanowire Detector (PND), which uses spatial multiplexing on a subwavelength scale to provide a single electrical output proportional to the photon number. The basic structure of the PND is the parallel connection of several NbN superconducting nanowires (100 nm-wide, few nm-thick), folded in a meander pattern. Electrical and optical equivalents of the device were developed in order to gain insight on its working principle. PNDs were fabricated on 3-4 nm thick NbN films grown on sapphire (substrate temperature TS=900C) or MgO (TS=400C) substrates by reactive magnetron sputtering in an Ar/N2 gas mixture. The device performance was characterized in terms of speed and sensitivity. The photoresponse shows a full width at half maximum (FWHM) as low as 660ps. PNDs showed counting performance at 80 MHz repetition rate. Building the histograms of the photoresponse peak, no multiplication noise buildup is observable and a one photon quantum efficiency can be estimated to be QE=3% (at 700 nm wavelength and 4.2 K temperature). The PND significantly outperforms existing PNR detectors in terms of simplicity, sensitivity, speed, and multiplication noise.

Abstract: A review of development and characterization of the nanostructures consisting of several meander sections, all connected in parallel was presented. Such geometry leads to a significant decrease of the kinetic inductance, without a decrease of the SSPD active area. A new type of SSPDs possess the QE of large-active- area devices, but, simultaneously, allows achieving short response times and the GHz-counting rate. This new generation of superconducting detectors has another significant advantage for quantum key distribution, they have a photon number resolving capability and can distinguish more photons.

Abstract: Coherence-domain imaging systems can be operated in a single-photon-counting mode, offering low detector noise; this in turn leads to increased sensitivity for weak light sources and weakly reflecting samples. We have demonstrated that excellent axial resolution can be obtained in a photon-counting coherence-domain imaging (CDI) system that uses light generated via spontaneous parametric downconversion (SPDC) in a chirped periodically poled stoichiometric lithium tantalate (chirped-PPSLT) structure, in conjunction with a niobium nitride superconducting single-photon detector (SSPD). The bandwidth of the light generated via SPDC, as well as the bandwidth over which the SSPD is sensitive, can extend over a wavelength region that stretches from 700 to 1500 nm. This ultrabroad wavelength band offers a near-ideal combination of deep penetration and ultrahigh axial resolution for the imaging of biological tissue. The generation of SPDC light of adjustable bandwidth in the vicinity of 1064 nm, via the use of chirped-PPSLT structures, had not been previously achieved. To demonstrate the usefulness of this technique, we construct images for a hierarchy of samples of increasing complexity: a mirror, a nitrocellulose membrane, and a biological sample comprising onion-skin cells.

Abstract: The dependence of the noise equivalent temperature difference (NETD) of a superconducting integrated receiver (SIR) on the receiver noise temperature and the inputsignal level has been investigated. An unprecedented NETD of 13±2 mK has been measured at a SIR noise temperature of 200 K, intermediate-frequency bandwidth of 4 GHz, and time constant of 1 s. With a decrease in the input signal, an improvement in the NETD is observed. This effect is explained by a reduction in the influence of the instabilities of the receiver power supply and the amplification circuit that occur when the input signal is decreased.

Abstract: Terahertz time-domain-spectroscopy (THz-TDS) has emerged as a versatile spectroscopic technique, and an alternative to powder X-ray diffraction in the characterization of molecular crystals. We tested the ability of terahertz spectroscopy to distinguish between chiral and racemic hydrogen-bonded cocrystals that are similar in molecular and supramolecular structure. Terahertz spectroscopy readily distinguished between the isostructural cocrystals of theophylline with chiral and racemic forms of malic acid which are almost identical in molecular structure and supramolecular architecture. Similarly, the cocrystals of theophylline with chiral and racemic forms of tartaric acid, which are similar at the molecular level but dissimilar in crystal packing, were distinguished unequivocally. The investigation of the same cocrystals using X-ray powder diffraction and Raman spectroscopy suggested that THz-TDS is comparable in sensitivity to diffraction methods and more sensitive than Raman spectroscopy to changes in cocrystal architecture. The differences in spectra acquired by THz-TDS could be further enhanced by cooling the samples to 109 K.

Abstract: We review radiometric techniques that take advantage of photon counting and stem from the quantum laws of nature. We present a brief history of metrological experiments and review the current state of experimental quantum radiometry.

Abstract: The Atacama Pathfinder EXperiment (APEX) 12m telescope is operating on the Llano Chajnantor, Chile, since 2003 and a set of state of the art sub-millimeter receivers have been installed for frequencies spanning from 150 GHz to 1500 GHz. In 2008, a balanced 1.3 THz Hot Electron Bolometer (HEB) receiver was installed for the atmospheric window 1250-1380 GHz. This instrument is part of a 4-channel receiver cryostat with the other channels being 211-275 GHz, 275-370 GHz and 380-500 GHz Sideband Separating (SSB) SIS receivers. This paper presents the first observations obtained so far with the 1.3 THz band during its first months of operation. The sky measurements were taken during opportunistic commissioning and science verification phases, when the weather conditions were sufficiently good with a Precipitable Water Vapor (PWV) below 0.25 mm, which was the case only a few nights during these months. We present the first observations of the molecular transition CO J=(11-10) line on different sources such as Orion-FIR4, CW-Leo and SgrB2(M). We describe the many challenges and difficulties encountered for achieving successful THz observations from a large sub-millimeter ground-based telescope.

Abstract: We develop and study a hot-electron bolometer mixer made of a two-layer NbN–Au film in situ deposited on a silicon substrate. The double-sideband noise temperature of the mixer is 750 K at a frequency of 2.5 THz. The conversion efficiency measurements show that at the superconducting transition temperature, the intermediate-frequency bandwidth amounts to about 6.5 GHz for a mixer 0.112 μm long. These record-breaking characteristics are attributed to the improved contacts between a sensitive element and a helical antenna and are reached due to using the in situ deposition of NbN and Au layers at certain stages of the process.

Abstract: We present the results of direct measurements of the temperature resolution of an HEB receiver operating at 810 GHz, in both continuum and spectroscopic modes. In the continuum mode, the input of the receiver was switched between black bodies with different physical temperatures. With a system noise temperature of around 1100 K, the receiver was able to resolve loads which differed in temperature by about 1 K over an integration time of 5 seconds. This resolution is significantly worse than the value of 0.07 K given by the radiometer equation. In the spectroscopic mode, a gas cell filled with carbonyl sulphide (OCS) gas was used and the emission line at 813.3537060 GHz was measured using the receiver in conjunction with a digital spectrometer. From the observed spectra, we determined that the measurement uncertainty of the equivalent emission temperature was 2.8 K for an integration time of 0.25 seconds and a spectral resolution of 12 MHz, compared to a 1.4 K temperature resolution given by the radiometer equation. This relative improvement is due to the fact that at short integration times the contribution from 1/f noise and drift are less dominant. In both modes, the temperature resolution was improved by about 40% with the use of a feedback loop which adjusted the level of an injected microwave radiation to maintain a constant operating current of the HEB mixer. This stabilization scheme has proved to be very effective to keep the temperature resolution of the HEB receiver to close to the theoretical value given by the radiometer equation.

Abstract: This review surveys the physical principles and recent developments in manufacturing single-photon sources. Special emphasis is placed on important potential applications such as linear optical quantum computing (LOQC), quantum key distribution (QKD) and quantum metrology that drive the development of these sources of single photons. We discuss the quantum-mechanical properties of light prepared in a quantum state of definite photon number and compare it with coherent light that shows a Poissonian distribution of photon numbers. We examine how the single-photon fidelity directly influences the ability to transmit secure quantum bits over a predefined distance. The theoretical description of modified spontaneous decay, the main principle behind single-photon generation, provides the background for many experimental implementations such as those using microresonators or pillar microcavities. The main alternative way to generate single photons using postselection of entangled photon pairs from parametric down-conversion, will be discussed. We concentrate on describing the underlying physical principles and we will point out limitations and open problems associated with single-photon production.

Abstract: A counterexample to the 'additivity question', the most celebrated open problem in the mathematical theory of quantum information, casts doubt on the possibility of finding a simple expression for the information capacity of a quantum channel.

Abstract: We present a fully automated quantum key distribution prototype running at 625 MHz clock rate. Taking advantage of ultra low loss fibres and low-noise superconducting detectors, we can distribute 6,000 secret bits per second over 100 km and 15 bits per second over 250km.

Abstract: We are developing the Atacama Large Millimeter/Submillimeter Array (ALMA) Band 10 (787-950 GHz) receiver cartridge. The incoming beam from the 12-m antenna is reflected by a pair of two ellipsoidal mirrors placed in the cartridge, and then split into two orthogonal polarizations by a free-standing wire-grid. Each beam enters a corrugated feed horn attached to a double-side-band (DSB) mixer block. The mixer uses a full-height waveguide and an NbTiN- or NbN-based superconductor-insulator-superconductor (SIS) mixer chip. We are testing the following three types of mixer chips: 1) Nb SIS junctions + NbTiN/SiO2/Al tuning circuits on a quartz substrate, 2) Nb SIS junctions + NbN/SiO2/Al tuning circuits on an MgO substrate, and 3) NbN SIS junctions + NbN or NbTiN tuning circuits on an MgO substrate. The IF system uses a 4-12-GHz cooled low-noise InP-based MMIC amplifier developed by Caltech. So far, the type 1) has shown the best performance. At LO frequencies from 800 to 940 GHz, the mixer noise temperatures measured by using the standard Y-factor method were below 240 K at an operating physical temperature of 4 K. The lowest noise temperature, 169 K, was obtained at the center frequency of the band 10, as designed. These well-developed technologies will be implemented in the band 10 cartridge to achieve the ALMA specifications.

Abstract: Superconducting nanowire single-photon detectors (SNSPDs or SSPD) are highly promising devices in the growing field of quantum information and communications technology. We have developed a practical SSPD system with our superconducting thin films and devices fabrication, optical coupling packaging, and cryogenic technology. The SSPD system consists of six-channel SSPD devices and a compact Gifford-McMahon (GM) cryocooler, and can operate continuously on 100 V ac power without the need for any cryogens. The SSPD devices were fabricated from high-quality niobium nitride (NbN) ultrathin films that were epitaxially grown on single-crystal MgO substrates. The packaged SSPD devices were temperature stabilized to 2.96 K ± 10 mK. The system detection efficiency for an SSPD device with an area of 20 × 20 ¿m2 was found to be 2.6% and 4.5% at wavelengths of 1550 and 1310 nm, respectively, at a dark count rate of 100 Hz, and a jitter of 100 ps full-width at half maximum. We also performed ultrafast BB84 quantum key distribution (QKD) field testing and entanglement-based QKD experiments using these SSPD devices.

Abstract: We designed superconducting nanowire single-photon detectors (SNSPDs) integrated with silver optical antennae for free-space coupling and a dielectric waveguide for fiber coupling. According to our finite-element simulation, (1) for the free-space coupling, the absorptance of the NbN nanowire for TM-polarized photons at the wavelength of 1550 nm can be as high as 96% by adding silver optical antennae; (2) for the fiber coupling, the absorptance of the NbN nanowire for TE-like-polarized photons can reach 76% including coupling efficiency at the wavelength of 1550 nm by adding a silicon nitride waveguide and an inverse-taper coupler.

Abstract: Microwave kinetic inductance detectors have great potential for large, very sensitive detector arrays for use in, for example, submillimeter imaging. Being intrinsically readout in the frequency domain, they are particularly suited for frequency domain multiplexing allowing ~1000 s of devices to be readout with one pair of coaxial cables. However, this moves the complexity of the detector from the cryogenics to the warm electronics. We present here the concept and experimental demonstration of the use of fast Fourier transform spectrometer readout, showing no deterioration of the noise performance compared to the low noise analog mixing while allowing high multiplexing ratios.

Abstract: Quantum Darwinism describes the proliferation, in the environment, of multiple records of selected states of a quantum system. It explains how the quantum fragility of a state of a single quantum system can lead to the classical robustness of states in their correlated multitude; shows how effective `wave-packet collapse' arises as a result of the proliferation throughout the environment of imprints of the state of the system; and provides a framework for the derivation of Born's rule, which relates the probabilities of detecting states to their amplitudes. Taken together, these three advances mark considerable progress towards settling the quantum measurement problem.

Abstract: Interest in research in the terahertz range is driven by a great number of various applications, where terahertz instruments may play a leading role. To name just a few, such applications include study of the cosmic microwave background radiation and the distribution of the dark matter, medicine, navigation, fire alarm, security systems and environmental monitoring. The paper discusses the possibility of using a receiver based on the hot-electron effect in superconducting films as an imaging system. We present the results of the noise equivalent temperature difference (NETD) measurements performed with a hot-electron bolometer mixer made from a thin superconducting film. The receiver with a noise temperature of ~ 3800 K at a local oscillator frequency of 300 GHz a bandwidth of 500 MHz and an integration time of 1 s has offered an NETD of 0.5 K. We have also developed a technique that enabled us to reduce the contribution of the mixer gain fluctuations to the overall system instability. As of this writing, the above value of the NETD is the lowest value offered for this type of receiver, which indicates the possibility to use such receivers in real-time imaging systems. The technique offered in the paper for achieving the limiting value of the NETD offers an alternative to the phase-locking scheme.
Представены результаты измерения флуктуационной чувствительности (NETD – noise equivalent temperature difference) болометрического смесителя на эффекте разогрева электронного газа в тонких сверхпроводящих пленках. Получено предельное значение NETD, равное 0,5 К, при шумовой температуре приемника 3800 К, ширине полосы преобразования 500 МГц, постоянной времени 1 с и частоте гетеродина 300 ГГц. Разработана методика достижения предельной флуктуационной чувствительности, позволяющая избежать влияния нестабильности коэффициента преобразования смесителя.

Abstract: Разработан и исследован смеситель на горячих электронах, изготовленный из двуслойной плёнки NbN-Au, осаждённой на кремневую подложку in situ. Двухполосная шумовая температура устройства составила 750 К на частоте 2.5 ТГц. Измерения эффективности преобразования для смесителя длиной 0.112 мкм вблизи температуры сверхпроводящего перехода показали полосу промежуточных частот около 6.5 ГГц. Эти результаты являются рекордными и были получены за счёт улучшения контактов между чувствительным элементом и спиральной антенной при замене технологического маршрута с нанесением слоёв NbN и Au в отдельных процессах на технологический процесс, в котором данные слои наносятся in situ без нарушения вакуума.

Abstract: Этап №1 (дата окончания: 30.09.2009)
Разработана методика изготовления сверхпроводниковых однофотонных детекторов (SSPD) с монокристаллической структурой пленки сверхмалой толщины. Изготовлены экспериментальные образцы сверхпроводниковых однофотонных детекторов (SSPD). Разработана методика пакетирования сверхпроводникового однофотонного детектора в оптический узел с одномодовым оптоволокном. Изготовлены экспериментальные образцы приемных модулей на основе однофотонных сверхпроводниковых детекторов из NbN-нанопленок.
Этап №2 (дата окончания: 28.10.2009)
Разработаны методы диагностики КМОП микросхем, гетероструктур и лазеров на квантовых точках и методика измерения мощности излучения полупроводниковых лазеров на квантовых точках с использованием сверхпроводниковых однофотонных детекторов (SSPD). Проведена технико-экономическая оценка рыночного потенциала полученных результатов.