Antennacoupled Microwave Kinetic Inductance Detectors MKIDs

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Antenna-coupled Microwave Kinetic Inductance
Detectors (MKIDs)

• JPL Peter Day, Rick Leduc, Ben Mazin, Alexey
  Goldin
• Caltech Anastasos Vayonakis, Shwetank Kumar,
  Jiansong Gao, Jonas Zmuidzinas

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MKID Principle of Operation

• Non-equilibrium superconducting detector
• Microwave readout of quasiparticles
• Quasiparticles change the surface impedance
• Ls Kinetic inductance
• Rs Dissipation
• Use a thin-film resonator to sense LS, RS
• Measure changes in resonance frequency
• Phase shifts

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Thin Film Resonator Circuit
output
input

• CPW Al on Sapphire
• 200nm thick, V 2000mm3,
• L 3mm, fres 10 GHz,
• Q 55,000

CPW geometry
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Coupling to Radiation

• Antenna coupling
• Up to 700 GHz
• Microstrip coupling of power from planar antennas

Broad- band array antenna
Key
Nb Ground plane
Nb Microstrip
MKID detector
Aluminum MKID
Slots
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Antenna-coupled Devices

• Dual-polarization 350GHz slot array antenna
• Detector and antenna fabricated in 3 mask levels

Slot array antenna (single pixel)
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Efficiency Measurements
Antenna
Band- Pass filter
Black- body

• Self Recombination

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Multiplexing
In
Out

• Powerful multiplexing strategy
• Many detectors are coupled to a single feedline
• Microwave readout means lots of bandwidth per
  detector
• Many channels per microwave amplifier

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Multiplexed Readout Electronics

• Digital techniques
• Recently demonstrated with MKIDs (see talk E54 by
  B. Mazin.)
• Commercially available PCI cards make up nearly
  the entire system.
• 256 channels per board possible (eg. Pentek
  7640).

• Practically, 100MHz bandwidth limits us to 50
  channels
• More bandwidth coming

Pentek Dual Digital Up/Downconverter PCI with
FPGA
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Sensitivity

• Sensitivity is limited from intrinsic noise
  from the detector
• Dielectric noise

• Sensitivity depends on power absorbed because
  of self-recombination
• Sensitivity is now good enough for ground based
  imaging where atmospheric noise is 3 times the
  BLP
• Approaching sensitivity required for CMB-pol

Ground-based mm/submm imaging
CMPpol
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Plans

• Multicolor pixels with microstrip band-defining
  filters 1.4mm 750mm

• Polarimeters with integrated polarization
  modulators

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Summary

• Demonstrated working submillimeter detectors
• Advantages of MKIDs
• Ease of fabrication
• High multiplexing factor
• gt 1000 per cold amplifier
• Digital readouts 50 or more channels/ board
• Simplified array development
• Warm electronics
• Interchangeable, reusable

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Improve SensitivityEtching the Substrate

• Remove the dielectric in regions of high field

20 mm