WPASM5

22 Jun 2016, 09:00 → 24 Jun 2016, 17:25 Europe/Rome

U4/08 (University of Milano-Bicocca)

Andrea Giachero (MIB), Angelo Enrico Lodovico Nucciotti (MIB)

In the last decade the interest in superconductive microresonator detectors has increased thanks to their broad spectrum of possible applications. Currently arrays of these detectors are being developed together with frequency multiplexed readouts and ultra-low noise parametric amplifiers for different applications such as photon and dark-matter detection, neutrino and double-beta decay experiments, quantum information and homeland security applications. The workshop will be dedicated to superconductive microresonators detectors and related topics, with the purpose of exchanging knowledge, new ideas, to present recent advancements and improvements, and to discuss their applications.

The workshop will be divided in the following sections:

1. Physical effects in superconductive microresonators;
2. Materials and Fabrication;
3. MKIDs for optical, infrared, and millimeter wave telescopes;
4. MKIDs for other applications;
5. Electronics and multiplexed readout;

The workshop agenda is now available.


The poster of WPASM5 workshop can be downloaded here.


 Scientific Committee

● Andrea Giachero	INFN Milano-Bicocca
● Angelo Nucciotti	University and INFN Milano-Bicocca
● Angiola Orlando	INFN Genova
● Marco Vignati	INFN Roma1

Local Organizer Committee (LOC)

● Elena Ferri	INFN Milano-Bicocca
● Andrea Giachero	INFN Milano-Bicocca
● Angelo Nucciotti	University and INFN Milano-Bicocca

Workshop Secretariat

● Marco Faverzani	University and INFN Milano-Bicocca
● Andrei Puiu	University and INFN Milano-Bicocca

Wednesday, 22 June

09:00 → 09:30 Registration

09:30 → 12:05 Session 1: MKIDs for optical, infrared, and millimeter wave telescopes - Part 1

Chairs:
Erik Shirokoff: 9:30 - 10:45;
Johannes Hubmayr: 11:15 - 12:30;

09:30 MKIDs for IR, optical and X-ray astronomy

The Mazin Lab at UC Santa Barbara develops MKID arrays for astronomical applications in the optical to IR wavelength range. I will present results from ARCONS, a 2024 pixel MKID array and the first optical MKID camera used for astronomical observations. I will further give an overview over the development and commissioning of DARKNESS and MEC, MKID cameras with 10.000 and 20.000 pixel respectively that we are developing for direct exoplanet imaging behind coronagraphs at the Hale telescope at Palomar Observatory and the Subaru telescope on Mauna Kea.

Speaker: Dr Gerhard Ulbricht (UCSB)

Slides 01.G.Ulbricht.WPASM5.MKIDsForInfraredToOpticalAstronomy.pdf

09:55 Development of DESHIMA: Superconducting on-chip spectrometer for submillimeter wave cosmology

Ultra-wideband millimeter-submillimeter wave spectrometry can become a very efficient method for rapidly determining the redshift of dusty starbutst galaxies in the early Universe. We are developing a new instrument, DESHIMA (Deep Spectroscopic High-redshift Mapper), which takes advantage of the multiplexibility of KIDs to realize a spectrometer that covers the entire submillimeter band (326-905 GHz), with a frequency resolution of f/df = 500, and up to 7 spatial pixels. DESHIMA is remarkably compact, thanks to the on-chip filterbank spectrometer design, and also the adoption of an adiabatic demagnetization refrigerator (ADR) to operate the KIDs at 150 mK. The filterbank spectrometer chip consists of the following components: (1) a leaky-lens antenna to couple a linearly polarized beam to a coplanar waveguide (CPW) over the wide DESHIMA band, (2) an array of superconducting narrow band filters, each being a quarter-wavelength CPW resonator made of superconducting NbTiN, and (3) NbTiN/Al hybrid CPW KIDs. In the conference we will give an overview on the recent progress of DESHIMA, focusing especially on the development of the on-chip filterbank.

Speaker: Dr Akira Endo (TU Delft)

10:20 GroundBIRD - KIDs meet the cosmic inflation

The cosmic inflation is a promising scenario to describe the origin of the Big Bang universe. Precise measurements of the cosmic microwave background (CMB) radiation, in particular its polarization patterns larger than one degree-scale, are the best experimental approach to prove it. The GroundBIRD is one of the CMB polarization experiments, we plan to start observation at Canary Island from 2017. To measure such large angular scale patterns, we implement some own features, e.g. high-speed scan modulation and kinetic inductance detectors (KIDs). The high-speed scan modulation mitigates effects of 1/f noise due to instruments, atmospheric fluctuation and so on. The scan speed is roughly two orders of magnitude faster than the speed of conventional telescopes. A patent pending technology, continuous rotation of the telescope along the azimuth with the maintenance of the cold temperature, realizes this scan strategy. Because the scan speed is fast, it is natural to use fast time response detector, KID. We have horn antenna coupled KID arrays in 145 and 220 GHz bands. The signal via each horn is picked up by planar OMT, and it is transmitted to KIDs. A combined simulation using three types of simulators, named ``hybrid simulation,'' allows us to optimize millimeter-wave circuits: components from the OMT to the resonator. In the KID fabrication stage, we also perform ``hybrid processing'': a combination of an aligner and stepper for exposure of the photo-resist. Single KID-array wafer consists of one feed-line, 110 (224) resonators, and 55 (112) millimeter-wave circuits for 145 GHz (220 GHz) band. Since each resonator has a different design, the aligner is the natural solution to fabricate the feed-line and resonators. On the other hand, the millimeter-wave circuits require finer resolution than specifications of the aligner, and we use the stepper for their fabrication. We will present development status of the detector and other instruments.

Speaker: Prof. Osamu Tajima (KEK)

Slides 03.O.Tajima.WPASM5.GroundBIRD.pdf

10:45 Coffee break

11:15 Laboratory Evaluation of DESHIMA: A Submillimeter Wave On-chip Filterbank Spectrometer

DESHIMA is an on-chip filter bank spectrometer that utilizes NbTiN superconducting resonant filters. The output signal of each filter is read out by microwave kinetic inductance detectors (MKIDs). The high multiplexing capability of MKIDs enables us to realize wide-band coverage with moderate frequency resolution. The target frequency band of DESHIMA is 326-905 GHz with frequency resolution of F/dF = 500. The first generation of DESHIMA, covering a frequency range of 326-368 GHz, is planned to be installed on the ASTE telescope in the Atacama desert. The main components of the DESHIMA instrument are 4 K cold optics cooled down by a pulse tube cooler, 100 mK light-tight box for MKIDs cooled down by an adiabatic demagnetization refrigerator (ADR), and an FFT based multi-tone readout circuits. The design, fabrication, assembly, and cool down test of the instrument have been successfully carried out by collaboration between Delft University of Technology and SRON. Laboratory-based tests to characterize the whole DESHIMA system are being carried out with a photomixing THz CW source. In this talk, we would like to present about the DESHIMA instrument focusing on cryostat integration and characteristics of the filter bank evaluated in the test system.

Speaker: Dr Kenichi Karatsu (TU Delft)

Slides 04.K.Karatsu.WPASM5.LaboratoryEvaluationOfDESHIMA.pdf

11:40 Kinetic Inductors for Measurements of the Cosmic Microwave Background

We are developing kinetic inductance detectors (KIDs) for measurements of the polarization of the cosmic microwave background (CMB) radiation. Our goal is to extend the range of applicability of KIDs to wavelengths as long as 1 cm. As a first step, we have designed, fabricated, and tested a 20-pixel prototype LEKID array using a simple quasi-lumped element microstrip design optimized for detecting 100 GHz (3 mm) signals. The devices include superconducting micro-resonators formed from TiN/Ti/TiN trilayers which are deposited by pulsed DC reactive magnetron-sputtering. We discuss design considerations for the array, as well as preliminary detector characterization measurements and results from a study of TiN trilayer properties.

Speaker: Prof. Peter Timbie (University of Wisconsin - Madison)

Slides 05.P.Timbie.WPASM5.KIDforCMB.pdf

12:05 → 14:00 Lunch

14:00 → 15:45 Session 1: MKIDs for optical, infrared, and millimeter wave telescopes - Part 2

Chair: Martino Calvo

14:00 LEKID for space applications

Kinetic Inductance Detectors (KID) are now routinely used in ground-based telescopes. Large arrays, deployed in formats up to kilopixels, exhibit state-of-the-art performance at millimeter (e.g. 120-300 GHz, NIKA and NIKA2 on the IRAM 30-meters) and sub-millimeter (e.g. 350-850 GHz AMKID on APEX) wavelengths. In view of future utilizations above the atmosphere, we have studied in detail the interaction of ionizing particles with LEKID (Lumped Element KID) arrays. We have constructed a dedicated cryogenic setup that allows to reproduce the typical observing conditions of a space-borne observatory. We will report the details and conclusions from a number of measurements. We give a brief description of our short term project, consisting in flying LEKID on a stratospheric balloon named B-SIDE.

Speaker: Dr Alessandro Monfardini (CNRS Grenoble)

Slides 01.A.Monfardini.WPASM5.FromNIKA2ToAboveAtmosphere.pdf

14:25 Study of Microwave Kinetic Inductance Detectors made of Crystalline Niobium

During these last decades, MKIDs have been increasingly used in the field of astrophysics. These superconductive coplanar waveguide resonators continue to be developed to improve their sensitivity to radiation from submillimetre to X-ray wavelengths. The Advanced Technology Centre of NAOJ is developing MKIDs for astronomical observations such as CMB B-mode search. One of the parameters that characterizes a MKID is the quality factor Q of the resonance peak. This Q factor, which is determined by the losses in the system, can reach values as high as 10^6. The maximum quality factor Q of superconducting resonators is often not limited by the superconducting material or radiation, but instead by dissipation due to an amorphous dielectric. In this contribution, we would like to present our new study on MKIDs made of crystalline niobium. The realization of the detectors is all carried out in the ATC clean room. Nb layer is deposited on sapphire wafer by sputtering process using a direct target. During the deposition, the substrate is heated up to 800 °C. The important parameters are the vacuum quality and the speed of the rate deposition in order to obtain the purest possible crystalline layer. Then, we fabricate MKIDs based on this crystalline Nb layer. In a first step, the characterization of the crystalline Nb layer itself gave a critical temperature of 9,4 K and a resistivity of 15,8 µm.cm that are not far from the theoretical values. Most important was the result of the Residual Resistivity Ratio measurement. RRR reached values ranging from 50 up to 100. In a second step, the MKIDs presented very nice resonance peaks with internal quality factor Qi up to 10^6. We will present a larger characterization of crystalline Nb MKID and compare our results to similar MKIDs that we already fabricated with Nb layer but not a crystalline one.

Speaker: Dr Agnes Dominjon (NAOJ)

Slides 02.A.Dominjon.WPASM5.SingleCrystalNiobium.pdf

14:50 Responsivity and electrothermal feedback in Kinetic Inductance Detectors

We review and present simulations of our complete (large-signal, small-signal, and noise) electrothermal model of Kinetic Inductance Detectors [1]. Our geometry-independent model includes both the behaviour of the microwave resonator as well as the heat capacities of and thermal conductances between the superconductor quasiparticles, superconductor phonons, substrate phonons, and thermal bath. Using our previous results on microwave readout power heating, we quantify the electrothermal feedback due to the dependence of readout power absorbed on quasiparticle effective temperature. With this model we calculate the large-signal, small-signal, and noise dynamical behaviour of KIDs, in particular the changes in mixer I and Q output due to signal power, for a range of device operating parameters including varying thermal isolation from the bath. We use this to find optimal operating points for detection of signal power as measured by responsivity and NEP, including combinations of I and Q channel readout, for both symmetric and highly asymmetric resonance curves. We also discuss how the electrothermal feedback affects responsivity and NEP, and how changes to the thermal configuration are related to the response time of the detector and noise measured in the detector output. We briefly comment on how the model can be use to analyse the behaviour of KIDs operating in a phonon detection mode. [1] Thomas, C. N., Withington, S. & Goldie, D. J. Electrothermal model of kinetic inductance detectors. Supercond. Sci. Technol. 28, 045012 (2015).

Speaker: Mr Tejas Guruswamy (University of Cambridge)

Slides 03.T.Guruswamy.WPASM5.ResponsivityAndElectrothermalFeedbackInKID.pdf

15:15 Coffee break

15:45 → 18:00 Session 2: Materials and Fabrication

Chair: Gerhard Ulbricht

15:45 Uniform sub-stoichiometric titanium nitride films for mm-wave kinetic inductance detectors

We describe the fabrication of homogeneous sub-stoichiometric titanium nitride films for microwave kinetic inductance detector (KID) arrays. Using a 6” sputtering target and a homogeneous nitrogen inlet, the variation of the critical temperature over a 2” wafer was reduced to <25 %. Measurements of a 132-pixel KID array from these films reveal a sensitivity of 16 kHz/pW in the 100 GHz band, comparable to the best aluminium KIDs. We measured a noise equivalent power of NEP = 3.6×10-15 W/sqrt(Hz). Finally, we describe possible routes to further improve the performance of these TiN KID arrays

Speaker: Dr Eduard Driessen (IRAM)

Slides 01.E.Driessen.WPASM5.Sub-stoichiometricTiN.pdf

16:10 UVOIR MKID Design and Material Developments

We report on the development of microwave kinetic inductance detectors (MKIDs) for the ultra-violet, optical, and near-IR (UVOIR) wavelength regime. UVOIR MKIDs have been rapidly evolving in terms of resonator geometry, array size, and even choice of superconductor material. We detail this recent history of UVOIR MKID development and examine the detector design goals and challenges put forth by the next generation of MKID instruments. The first generation of UVOIR MKID instruments had a variety of array issues, such as lower than desired feedline and pixel yields, energy resolution, and quantum efficiency. Most notably, we worked on increasing the total pixel yield by switching the superconducting film to PtSi, which was expected to be spatially much more uniform, but less well understood than many of its low TC superconductor counterparts. We have had extremely promising results with PtSi thin films on sapphire substrates, such as resonator internal quality factors of over one million and spatial uniformity in sheet resistance about an order of magnitude better than that of the previously used TiN films. We are currently in the process of adapting these films in our kilopixel MKID array designs and are awaiting the initial testing of these devices.

Speaker: Mr Paul Szypryt (University of California, Santa Barbara)

Slides 02.P.Szypryt.WPASM5.UVOIRMKID.pptx

16:35 Fabrication of the CALDER light detectors

The goal of the CALDER (Cryogenic wide-Area Light Detectors with Excellent Resolution) project is the development of light detectors with large active area and noise energy resolution smaller than 20 eV RMS using phonon-mediated Kinetic Inductance Detectors (KIDs). The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work we present the fabrication process, starting from the silicon wafer arriving to the single chip. In the first part of the project we designed and fabricated KID detectors using aluminum. Detectors are designed by means of state-of- art software for electromagnetic analysis (SONNET). The Al thin films (40 nm and 60 nm) are evaporated on high quality, high resistivity (higher than 10 kΩ*cm) Si(100) substrates using an electron beam evaporator in a HV chamber. Detectors are made in direct-write mode, using Electron Beam Lithography (EBL), positive tone resist poly-methyl methacrylate (PMMA) and lift off process. To increase the energy resolution of our detectors we are changing the superconductor to sub-stoichiometric TiN, deposited by means of DC-magnetron reactive sputtering. For this kind of materials the fabrication method is subtractive and patterning occurs through negative tone resist Ar-n 7700 and Deep reactive Ion Etching (DRIE) process in SF 6 gas. Finally the chip is diced into 20x20 mm 2 chip and assembled in a oxigen free copper (OFC) holder using PTFE support and measured in dilution refrigerator with base temperature of 10 mK.

Speaker: Ivan Colantoni

Slides 03.I.Colantoni.WPASM.CALDERLightDetectors.pdf

17:00 Compact and high quality microwave resonators made from superconducting aluminium-oxide wires.

One aspect of state of the art superconducting circuits are low loss inductive elements, e.g. for resonators or qubit loop inductances. We present a novel approach for compact and high quality microwave circuits using thin film wires made from superconducting aluminium-oxide. Due to the nano-scale grain size, the material was mostly investigated with the focus on the intrinsic granularity and at low frequencies in the past. The in the film growth process added oxygen impurities alter the sheet resistance, superconducting transition temperature and therefore also the kinetic inductance of a wire. At moderate film thicknesses of around 20nm, sheet resistances in the kOhm range can be obtained, such that the kinetic inductance of superconducting wires dominates the total inductance. We show measurements of microwave coplanar waveguide resonators with high wave impedance and therefore compact design. At milli-Kelvin temperatures, quality factors as high as 1M have been obtained.

Speaker: Hannes Rotzinger (KIT Germany)

Slides 04.H.Rotzinger.WPASM.Aluminium-oxide.pdf

Thursday, 23 June

09:30 → 11:15 Session 3: MKIDs for optical, infrared, and millimeter wave telescopes

Chair: Andrea Tartari

09:30 The NIKA2 camera: commissioning and first results

The New IRAM KID Array 2 (NIKA2) instrument is a camera installed at the IRAM 30-meters telescope based on superconducting Kinetic Inductance Detectors. Reaching a total of more than 3000 pixels split between two separate bands (2mm and 1.15mm), and the ability to make polarization-sensitive observations in the lower wavelength channel, NIKA2 will be an fundamental tool for a wide spectra of astronomical applications in the years to come. Since its installation in September 2015, the instrument has been undergoing a series of commissioning campaigns. We describe the NIKA2 design and key features, and report on its successful installation on site. We conclude by showing some of the first results obtained during the commissioning. The state-of-the-art performance achieved by NIKA2 have paved the path for the many KID-based instruments that are currently under development, both for ground-based and space applications.

Speaker: Dr Martino Calvo (Institut Néel - CNRS Grenoble)

Slides 01.M.Calvo.WPASM5.NIKA2.pdf

09:55 New results from SuperSpec: developing an on-chip, mm-wave, KID-based, filter-bank spectrometer.

SuperSpec is a novel, ultra-compact spectrometer-on-a-chip for millimeter and submillimeter wavelength astronomy. Its very small size, wide spectral bandwidth, and highly multiplexed detector readout will enable construction of powerful multibeam spectrometers for high-redshift observations of dusty star forming galaxies and intensity mapping of spectral lines from unresolved sources. SuperSpec employs a filter bank consisting of planar, lithographed superconducting transmission line resonators. Each mm-wave resonator is weakly coupled to both the feedline and to the inductive portion of a lumped element Kinetic Inductance Detector (MKID). The design is realized using thin film lithographic structures on a Si wafer, with titanium nitride MKID resonators. Prototypes consisting of sparse arrays have demonstrated background-limited operation at a resolving power of R~100, adequate suppression of out-of-band pickup, and well characterized mm-wave filter bank channels. I'll discuss the most recent optical test results for 50-channel, field-ready, prototype die, and plans for the deployment of a four pixel, R=400 demonstration instrument covering the 195-310GHz band in 2017.

Speaker: Prof. Erik Shirokoff (University of Chicago)

Slides 02.E.Shirokoff.WPASM5.ResultsFromSuperSpec.pdf

10:20 The SpaceKIDs Project: Development of Kinetic Inductance Detector Arrays for Space Applications

Kinetic Inductance Detectors (KIDs) offer the unique combination of excellent sensitivity to THz radiation along with minimal cryogenic complexity. The goal of the SpaceKIDs project is to work on the developments needed to enable this technology for both low-background (astrophysical) and high-background (Earth-observing) applications. Two laboratory demonstrator systems have been built to evaluate array characteristics and performance in an environment representative of the two applications. In this talk I will present an overview of the SpaceKIDs programme, describe in detail the performance of the demonstrator systems, and highlight some of the major results, which are set to have a significant impact on the design and characterisation of the next generation KID arrays.

Speaker: Dr Pete Barry (Cardiff University)

Slides 03.P.Barry.WPASM5.SpaceKIDs.pdf

10:45 Coffee Break

11:15 → 12:30 Session 4: MKIDs for other applications - Part 1

Chair: Andreas Fleischmann

11:15 TKIDs: MKIDs (not only) for X-ray astronomy

The Mazin Lab at UC Santa Barbara develops Thermal Kinetic Inductance Detectors (TKIDs) for X-ray imaging spectroscopy. I will present our recent progress developing TKIDs for X-ray imaging spectroscopy in the 0.5 to 20 keV band. TKIDs are optimized for X-ray detection by suspending their inductor and a separate X-ray absorber on a freestanding Si3N4 membrane and by operating them as microcalorimeters. They have the potential to achieve time and energy resolutions comparable to TESs while retaining the passive multiplexibility of MKIDs, thus offering a promising and feasible way to kilo- or even mega-pixel X-ray detector arrays. With considerably saturated prototypes we have already demonstrated a TKID energy resolution of 75 eV at 5.9 keV, and I will elaborate on our plans to further improve our TKID design in order to find out how close to the projected TKID energy resolution of less then 0,1% we can get.

Speaker: Dr Gerhard Ulbricht (UCSB)

Slides 01.G.Ulbricht.WPASM5.TKID.pdf

11:40 CALDER: high sensitivity cryogenic light detector.

The current bolometric experiments searching for rare events as neutrino-less double beta decay or dark matter interaction demand for cryogenic light detectors with high sensitivity, large active area and excellent scalability and radio-purity in order to reduce their background budget. The CALDER project aims to develop such kind of light detectors implementing phonon-mediated Kinetic Inductance Detectors (KIDs). The goal for this project is the realization of a $5\times5$~cm$^2$ light detector working between 10 and 100~mK with a baseline resolution RMS below 20~eV. KIDs have already demonstrated their potentiality as direct detectors of photons for different astrophysical applications. The aim of our project is to apply this technology in Particle Physics, using indirect detection. These devices can be operated in a phonon-mediated approach, in which KIDs are coupled to a large insulating substrates in order to increase the active surface from a few mm$^2$ to 25~cm$^2$ We have already demonstrated the feasibility of a phonon-mediated KIDs-based light detectors, using aluminum sensors. These device reached a baseline sensitivity of 80~eV with an overall efficiency of about 10\%. Currently we are testing new materials (e.g. Ti-Al and non stoichiometric TiN) to enhance the sensitivity and reach the goal of our project. We will present our results and the physical interpretation of the device behaviour.

Speaker: Nicola Casali (ROMA1)

Slides 02.N.Casali.WPASM5.CALDER.pdf

12:05 General Purpose Terahertz Imaging Systems With Lumped Element KIDs

We are developing a terahertz imaging system based on arrays of lumped element kinetic inductance detectors (LEKIDs) for general purpose commercial/industrial applications. The recent demonstration of KID-Cam [1] has proven that this detector technology is suitable for deployment in a range of fields where high sensitivity, fast response, broad spectral coverage and low susceptibility to EMI are desirable. In this talk, I will present some of the results from our demonstration system and I will describe our progress - so far - towards the commercially ready system which we aim to have complete within the next 18-24 months. [1] Rowe, S., Pascale, E., Doyle, et al, “A passive terahertz video camera based on lumped element kinetic inductance detectors”, Review of Scientific Instruments, 87(3), p.033105., 2016

Speaker: Dr Sam Rowe (Cardiff University)

12:30 → 14:00 Lunch

14:00 → 14:25 Session 4: MKIDs for other applications - Part 2

Chair: Andreas Fleischmann

14:00 MKIDs for x-ray spectroscopy and neutrino mass measurement

Speaker: Mr Marco Faverzani (MIB)

Slides 04.M.Faverzani.WPASM5.Xrays.pdf

14:25 → 17:00 Session 5: Electronics and multiplexed readout

Chair: Akira Endo

14:25 Time domain simulator for KID arrays and their associated readout systems

We have developed a model for calculating the linear and non-linear behaviour of Kinetic Inductance Detectors (KIDs) in the time domain. Crucially, the simulator works in `real time', producing the time-sequence data that would be measured in an experiment. In other words, the value of every independent variable is specified at an instant in time, and then the value of every dependent variable is calculated at the same instant in time. It is not necessary to capture a long time sequence and then to analyse it as a single block of data, say through an FFT. It is straightforward to simulate large arrays and to include all aspects of readout tone generation and analysis: waveform synthesis, digitisation, up and down conversion, I-Q mixers, filters. The method is able to calculate the response to slowly time varying signals, as are found at submillimetre and far-infrared wavelengths, and fast transient signals, as are found at optical and x-ray wavelengths. We used the time-domain simulator to study the transient response, small-signal response, and pulsed response of single KIDs and their readout systems. It is straightforward to track the I and Q outputs as a function of time as independent parameters are varied. We have modelled large arrays, concentrating on effects such as phase delays in transmission lines, and cross talk between different pixels caused by overlapping resonances and sideband generation. The method is able to reproduce a wide range of complex phenomena seen experimentally. In the paper, we will review the theoretical background to the method, and describe a range of illustrative simulations.

Speaker: Ms Isabel Maria Bonachera Martin (Cavendish Laboratory, University of Cambridge)

Slides 01_WPASM_IsabelMariaBonacheraMartin.pdf

14:50 Readout of the BLAST-TNG MKID detectors

I will describe the status of the readout software and electronics for the BLAST-TNG linear polarization sensitive MKIDs arrays. The Balloon-borne Large Aperture Submillimeter Telescope (The Next Generation) will fly more than 3000 pixels combined with a 2.5m carbon fiber primary mirror to make diffraction limited observation at 250, 350 and 500 microns. It will map mearby molecular clouds and the diffuse galactic dust polarized emission with unprecedented detail. The 250 micron array has been integrated in the new cryostat and it is under test to establish the optical and polarization characteristics of the instrument. BLAST-TNG will demostrate the effectiveness of kilo-pixel MKID arrays for applications in submillimeter astronomy. It will fly from Antarctica in December 2017 for 28 days and it will be the first balloon borne telescope to offer a quarter of the flight for "shared risk" observing for the community.

Speaker: Dr Federico Nati (University of Pennsylvania)

Slides 02.F.Nati.WPASM.ReadoutOfBLAST-TNG.pdf

15:15 Coffee Break

15:45 Microwave SQUID multiplexing for high-speed applications

The Microwave SQUID Multiplexer combines dissipationless rf-SQUIDs and superconducting microwave resonators, encoding the signal from each input channels in its own microwave tone, summing many tones onto a common output channel. Its principal advantage over existing multiplexing technologies is the large (~4 GHz) available output bandwidth. This bandwidth allows the multiplexed readout of large numbers of conventional detectors, but also of faster detectors than could be usefully multiplexed before. For high-bandwidth applications such as the HOLMES neutrino mass experiment and x-ray beamline science we present a new microwave SQUID multiplexer design. This device targets an effective per-pixel sampling rate of 1 MHz and a multiplexing factor of 256 pixels per cryogenic amplifier, far exceeding existing technologies and enabling new measurements. We will discuss the performance of this device and our work with the room-temperature demultiplexing electronics to utilize its full per-pixel bandwidth capacity.

Speaker: Dr John Mates (NIST)

Slides 03.B.Mates.WPASM5.MSquid.pdf

16:10 Microwave SQUID multiplexing of large MMC detector arrays

Metallic magnetic calorimeters (MMCs) are the devices of choice for many spectroscopic applications since they provide a very good energy resolution, a very fast intrinsic signal rise time as well as an excellent linearity. While single MMCs or small detector arrays are typically read out by dc-SQUIDs, the readout of very large arrays requires a cryogenic multiplexing technique to reduce the parasitic heat load to the cold stage of the cryostat, the system complexity as well as cost. A very promising approach for the readout of very large MMC arrays is microwave SQUID multiplexing. Here, the initial detector signal is transduced into a resonance frequency shift of a related superconducting λ/4 microwave resonator by means of a non-hysteretic, unshunted rf-SQUID. By coupling many resonators - each with unique resonance frequency - to a common transmission line, this frequency domain multiplexing technique allows for the readout of hundreds or thousand pixels with only one HEMT amplifier and two coaxial cables. In this contribution we discuss the performance of a recently developed 64 pixel MMC detector array that is read out by means of an on-chip multiplexer and demonstrate the simultaneous readout of two MMCs by means of a microwave SQUID multiplexe

Speaker: Dr Andreas Fleischmann (Heidelberg University)

Slides 04.A.Fleischmann.WPASM5.muSQUID.pdf

16:35 Development and Performance of the Microwave SQUID Multiplexed TES Array for MUSTANG2

MUSTANG2 is a 90 GHz feedhorn-coupled, microwave SQUID-multiplexed TES bolometer array, with 215 unpolarized pixels. The microstrip-coupled detector technology was developed by a collaboration consisting of NIST, Princeton, the University of Chicago, the University of Colorado, and the University of Michigan. The collaboration has already produced detectors that have been thoroughly tested and deployed on SPTpol, ACTpol, and ABS. The microwave SQUID readout system developed for MUSTANG2 will eventually allow thousands of detectors to be read out with a single coaxial cable. This microwave SQUID multiplexer combines the proven abilities of millimeterwave TES detectors with the multiplexing capabilities of KIDs with no degradation in noise performance of the detectors. Each multiplexing device is read out using warm electronics consisting of a commercially available ROACH board, a DAC/ADC card, and an Intermediate Frequency mixer circuit. The hardware was originally developed by the UC Berkeley Collaboration for Astronomy Signal Processing and Electronic Research (CASPER) group, whose primary goal is to develop scalable FPGA-based hardware with the flexibility to be used in a wide range of radio signal processing applications. We present on the design and performance of the MUSTANG2 array, including the microwave SQUID multiplexed devices as well as the readout system and results from commissioning of MUSTANG2.

Speaker: Ms Sara Stanchfield (University of Pennsylvania)

Slides 05.S.Stanchfield.WPASM5.MUSTANG-2.pdf

17:00 → 17:25 Session 3a: MKIDs for optical, infrared, and millimeter wave telescopes

17:00 Superconducting resonators and integrated spectrometers for submillimeter spectroscopy in space

We are developing a highly integrated photonic spectrometer-on-chip called Microspec for application on space or balloon telescopes for submillimeter/THz astrophysics. All components including the detectors and optical dispersion elements are integrated into a single photonic chip, and utilize a highly confined microstrip architecture for immunity to stray radiation. We use low-loss superconducting niobium transmission lines with a 0.45 μm single-crystal silicon dielectric to produce a synthetic grating with spectral resolution and efficiency ultimately only limited by the intrinsic loss of crystalline Si at cryogenic temperatures. The photon detectors are half-wave resonator microstrip-line KIDs with aluminum top and Nb ground plane on 0.45 µm Si. We have built a laboratory demonstration version of Microspec in the 400—600 GHz band with 48 optical channels that operates with resolution R=64. We report on the optical measurements of the spectrometer channels, and on dark characterization of the KIDs. We successfully demonstrate end-to-end optical performance that matches the expected resolution of 64, achieve channel yield of 47 out of 48, and obtain uniform channel response. In addition we demonstrate high contrast in overlapping adjacent channels with zero out-of-band response in the 100-800 GHz range. The KIDs exhibit significantly reduced sensitivity performance due to smaller than expected internal quality factors. We present cryogenic microwave loss data that supports the existence of a contaminating hydrocarbon layer at the Si/Nb interface that is supported by transmission electron microscope images.

Speaker: Dr Omid Noroozian (NASA Goddard Space Flight Center / UMD)

Slides 04.O.Noroozian.WPASM5.microSPEC.pptx

Friday, 24 June

09:30 → 12:05 Session 6: MKIDs for optical, infrared, and millimeter wave telescopes

Chairs:
Peter Timbie: 09:30 - 10:45;
Omid Noroozian: 11:15 - 12:30;

09:30 Polarization-sensitive MKID arrays fabricated from TiN/Ti multilayers

In recent years, NIST has started a program to develop microwave kinetic inductance detectors (MKIDs) for polarimetric imaging applications over a broad range of observation frequencies (~90 GHz to 1.4 THz). In this talk, we overview the current status of feedhorn-coupled and dual-polarization sensitive MKIDs fabricated from Ti/TiN multilayer films. We describe extensive materials development, which has enabled uniform, Tc-tunable arrays on 100mm diameter substrates. We detail the lumped-element, dual-polarization sensitive pixel design and present measurements that demonstrate photon-noise limited sensitivity for thermal loads > 0.5 pW and polarization sensitivity with <2% cross-polarization at 250 micron. We discuss several aspects of low frequency device stability, including the dependence on LC resonator geometry and under different optical loading conditions. The impact in both the frequency and dissipation quadrature will be presented. Arrays of this architecture have been fabricated for the balloon-borne polarimeter BLAST-TNG. One challenge of this implementation is how to achieve the required, high multiplexed density when operating the devices from a 300 mK bath temperature, where one must be concerned with degraded quality factors from thermal quasiparticles. We present the 250 micron array design, which overcomes this challenge and contains 918 spatial pixels (1836 resonators) within a 100 mm diameter footprint and uses three microwave feedlines for readout. We also show initial measurement results, including photon-noise sensitivity, achieved coupling and total quality factors, and frequency collision rate. Lastly, we discuss how this design scales to other wavebands for other applications such as precision measurements of the polarization of the cosmic microwave background.

Speaker: Dr Johannes Hubmayr (NIST)

Slides 01.J.Hubmayr.WPASM5.TiN-TiMultilayerFilms.pdf

09:55 MoBiKID - Kinetic Inductance Detectors for upcoming B-mode satellite missions

Our comprehension of the dawn of universe grew incredibly during last years, pointing to the existence of the cosmic inflation. The primordial B-mode polarization of the Cosmic Microwave Background (CMB) represents a unique probe to confirm this hypothesis. The detection of such small perturbations of the CMB is a challenge that will be faced in the near future by a new dedicated satellite mission. In this talk I will describe MoBiKID, a new project recently funded by INFN, to develop an array of Kinetic Inductance Detectors able to match the requirements of a next-generation experiment. The detectors will feature a Noise Equivalent Power better than 5 10^(-18) W/Hz^0.5 and will be designed to minimize the background induced by cosmic rays, which could be the main limit to the sensitivity.

Speaker: Angelo Cruciani (ROMA1)

Slides 02.A.Cruciani.WPASM5.MoBiKID.pdf

10:20 Development of Octave-band Planar Ortho-Mode Transducer with MKID for LiteBIRD

LiteBIRD is a next-generation satellite mission for measuring the primordial B-modes polarization signals of CMB. We describe a design of octave-band corrugated horn coupled planar ortho-mode transducer (OMT) with Microwave Kinetic Inductance Detector (MKID) as a candidate detection technology for LiteBIRD. In our design, each single pixel contains 90 and 150 GHz two frequency bands, covering the maximum power part of CMB polarization signal. Through a 2.4 mm diameter circular waveguide, polarization signal are coupled to the 4-probe planar OMT structure silicon membrane, below which a backshort structure with quarter wavelength is fabricated by deep reaction-ion etching from the backside of silicon on insulator wafer. After planar OMT, a broadband coplanar waveguide (CPW) 180-degree hybrid is used to cancel higher modes from circular waveguide. An Al/Ti center strip acts as absorber to absorb higher modes signal and TE11 signal is transmitted to a CPW-to-microstrip (MS) transition structure for connecting MS 5-element Chebyshev diplexer and following MKID. For coupling signal to MKID, the center strip of MKID acts as ground of MS and absorber to generate quasi-particle. For testing, a 4-pixel model is designed, containing 16 MKIDs and 4 dark MKIDs. MKIDs are designed with Nb ground plane and Al/Ti bilayer center strip line to achieve low frequency response and high sensitivity. The 4-pixel broadband corrugated horn array is fabricated with high accuracy direct machining. Measurement shows that S11 parameter is lower than -10 dB from 80 GHz to 170 GHz and agree well with simulation. After calibration and testing, this prototype will be installed on Nobeyama 45-m telescope.

Speaker: Mr Shibo Shu (The University of Tokyo)

Slides 03.S.Shu.WPASM5.LiteBIRD.pdf

10:45 Coffee Break

11:15 Design and simulation of the Kinetic Inductance Detector based spectrograph (KIDSpec) demonstrator

We present the design of the demonstrator for KIDSpec, the Kinetic Inductance Detector based medium resolution spectrograph in the optical through near-IR band. This instrument uses the intrinsic energy resolution of MKIDs to distinguish photons from multiple diffraction orders using an échelle grating as the dispersion element. KIDSpec will use this order resolving capability to replace the cross-disperser in a traditional échelle spectrograph. A technology demonstrator is being built with a monochromator based light source, a low line density optical grating and an optical fibre feed into a custom-built cryostat which will cool the MKID array down to 100 mK. The readout is based on the Reconfigurable Open Architecture Computing Hardware (ROACH) board with a Python based data analysis pipeline. We have simulated the demonstrator in Python where we have explored the effects of the finite energy resolution (λ/Δλ) of MKIDs, choice of optical grating and size of the MKID array. The ability of the demonstrator to separate light from different orders and spectral reconstruction of various astrophysical sources is strongly dependent on the energy resolution. A low energy resolution leads to the misidentification of the order to which detected photons belong to, limits the highest order which can be identified and also affects the final spectral resolution. We will also present the effect of sky background on the signal to noise performance of the spectrograph and the potential of the instrument on current and future extremely large telescopes.

Speaker: Dr Sumedh Mahashabde (Department of Physics - Astrophysics, University of Oxford, OX1 3RH, Oxford, United Kingdom)

Slides 04.S.Mahashabde.WPASM5.KIDSpec.pdf

11:40 Horn-coupled LEKID arrays for balloon-borne measurements of the CMB

We are developing Horn-coupled Lumped Element Kinetic Inductance Detector Arrays close to the photon noise limit in the stratospheric environment for multi band Cosmic Microwave Background (CMB) balloon-borne experiments. For this reason, we are focused on four spectral bands: two bands at 150 and 200 GHz, able to characterize the CMB emission; and two bands at 350 and 480 GHz, able to characterize foreground emissions from residual atmosphere and interstellar dust. Our arrays have been designed to be sensitive to both polarizations of the incident radiation, and to operate in Background Limited Infrared Photodetection (BLIP) conditions with background power ranging from 3 to 60 pW (depending on the optical band of interest), making it possible to use them in the typical observing conditions at balloon-borne altitude. Multi-band focal planes with a large aperture telescope as OLIMPO, equipped with a Fourier Transform Spectrometer, for the study of the Sunyaev-Zeldovich effect in galaxy clusters, would be a natural implementation of this technology. We describe here the design and the electrical and optical simulations of these LEKID arrays and the status of their tests.

Speaker: Alessandro Paiella (Sapienza & ROMA1)

Slides 05.A.Paiella.WPASM5.Horn-coupledLEKID.pdf

12:05 → 12:30 Concluding Remarks