SuperSpec prototype device

Welcome to the Shirokoff lab

We build novel superconducting detectors, and use them to study high redshift galaxies and the CMB.

Introduction

Detectors for astronomy at millimeter and submillimeter wavelength reached the background limit - the point at which photon counting statistics dominate instrumental noise - years ago. It's no longer possible to build a more sensitive detector. The best we can do is pack more detectors into a receiver. As a result, focal planes have grown from single hand-assembled pixels to lithographically defined arrays comprised of hundreds of detectors. To meet the science goals of the coming decade, future instruments will need to employ massive focal planes and hundred-kilopixel arrays.

While we can't build a more sensitive detector, there's still plenty of opportunity to build a better one. One strategy is to make each pixel do more: using on-chip microwave circuits and broad-band antennas and optics to enable multichroic detectors and integral-field spectrometers, packing more bandwidth into each physical device. Alternatively, we can make each pixel cheaper, more robust, and easier to read out with multiplexed hardware.

Our lab is working on both goals. Using modern thin-film processes and electromagnetic simulation software, we're working to move optical elements on-chip, replacing bulky and expensive mechanical hardware with planar circuits. When it comes to simple fabrication and low cost multiplexing, few technologies can compete with kinetic inductance detectors (KIDs). These pair-breaking superconducting detectors can be fabricated in a few layers and read-out at densities of thousands of channels per coax cable, and are approaching the sensitivity required for even low-loading applications at mm wavelengths.

Current projects

Here are some of the projects that we're currently collaborating on.

SuperSpec

SuperSpec is a novel, ultra-compact spectrograph-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. 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 (KID). Incoming mm-wave radiation breaks Cooper pairs in the MKID, modifying its kinetic inductance and resonant frequency, allowing for frequency-multiplexed readout. The design is realized using thin film lithographic structures on a Si wafer, with titanium nitride MKID resonators. Today we have working prototypes that demonstrate narrow spectral bands, sufficiently low losses at mm-wavelength, and out-of-band absorption at less than 1 part in 10'000. We're currently testing several designs which should approach the background photon noise limit. We're currently preparing to fabricate and test a third generation design. In the next two years we will deploy a demonstration instrument with two 500-channel, R=700 spectrometers, one operating in the 1-mm atmospheric window and the other covering the 650 and 850 micron bands. Eventually we expect the same technology to enable a multi-object spectrometer with hundreds of pixels for a large telescope such as CCAT.

SPT-3G

SPT-3G, is the the third generation receiver for the 10 meter South Pole Telescope. SPT-3G will enable high signal-to-noise measurements of CMB B-mode polarization. This will lead to precise (∼0.06 eV) constraints on the sum of neutrino masses with the potential to directly address the neutrino mass hierarchy. It will allow a separation of the lensing and inflationary B-mode power spectra, improving constraints on the amplitude and shape of the primordial signal. Other science goals include the precise measurement of small-scale temperature anisotropy which will provide new constraints on the duration of the epoch of reionization, and information about large scale structure, galaxy cluster abundance based upon joint analysis with the overlapping Dark Energy Survey (DES). The SPT-3G detector design program is currently underway at Argonne National Labs, and we'll be working on device testing and receiver integration at the University of Chicago in the coming year.

TIME and TIME-Pilot

TIME, the Tomographic Ionized-Carbon Mapping Experiment (TIME) and the pathfinder project, TIME-Pilot, are a proposed imaging spectrometers that will measure reionization and large scale structure at redshifts 5-9. These instruments will measure the power spectrum of the emission from unresolved galaxies in narrow redshift slices, exploiting the 158 μm rest-frame emission of [CII], which becomes measurable at 200-300 GHz at reionization redshifts. The TIME-Pilot cryostat and grating spectrometers are currently being built at Caltech and JPL, with plans to observe from the JCMT within three years. Prototypes designs for on-chip spectrometers for TIME are now being tested.

Open positions

We're looking for new lab members at every level, from undergraduate to postdoc.

Want to work with us? If the idea of hands-on, table-top cosmology appeals to you, don't hesitate to send us a note or stop by to say hello.

There are plenty of opportunities for both short-term and long-term projects in our lab. At the moment most of our work is focused on designing, fabricating and testing new detectors and superconducting microwave circuits, and in commissioning new lab hardware. In the next few years there will be opportunities for instrument integration, deploying to the telescope, and analyzing astronomical data.

Publications

COMING SOON

Group Members

Contact

Interested in joining the lab, collaborating with us, or asking a question? Don't hesitate to stop by and say hello.

Email and telephone

Email: shiro@uchicago.edu
Voice: 773-834-5399
Fax: 773-834-8279
Office: 132 LASR
Lab: 022 LASR

US Postal mail

Erik Shirokoff, LASR 132
University of Chicago
5640 South Ellis Avenue,
Chicago, IL 60637

Packages (UPS/FedEx)

University of Chicago
PSD - CIS Shipping Dock
5741 South Drexel
Chicago, IL 60637
Attn: Erik Shirokoff, LASR 132

We're a part of the Astronomy & Astrophysics Department and the Kavli Institute for Cosmological Physics at the University of Chicago.