Progress at the LBNLXinran Li

09/14/20212021 LBNL QuantISED Collaboration Meeting

Outline

● Progress on the LBNL cryogenic test environment○ Tc measurements○ TES measurements/ environment improvement○ Development of RF sensors and readout system

● RF resonators, readout and noise○ Where multiplexing would help?○ TES with RF multiplexing, MKIDs.○ Readout: VNA / SMURF / GroundBIRD

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Current SPICE/HeRALD Progress at Lawrence Berkeley Lab

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Aritoki SuzukiPhysicist Staff Scientist

LBLGroup Lead

Vetri VelanPh.D. Candidate

UC BerkeleyAdvisor: D. McKinsey

Xinran LiChamberlain Fellow

LBLSPICE/HeRALD, QIS

Ryan GibbonsPh.D. StudentUC Berkeley

Advisor: P. Sorensen

TES characterization

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Tc measurement

Lakeshore 372 4-point resistance measurement.

Less than fW AC (~10Hz) excitation current with phase-lock amplification.

Low noise environment with mu-metal EM shield.

Cycle the bath temperature slowly and measure R(T) curves. Thermometers calibrated down to 7mK.

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Tc measurement

Lowering Tc increases TES energy resolution.

Tc depends on sputtering chamber ion composition. One interesting set of Tungsten samples with Ar/Xe mixture.

See full presentation here

A collection of samples can be found here

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Example tungsten film R(T) curve with 100% Xe in deposition chamber.

TES measurement setup

Customized bias circuit operated with battery for low noise

Quantum Design SQUID model 550• ~1pA/rtHz current noise previously installed for CMB sensors • Low 1/f noise need down to ~0.3 Hz• Planning to upgrade to faster SQUID readout system

Helium battery option to achieve clean noise spectrum.

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TES measurements

• IV curve for bias power, parasitic power, loop gain– Measured DM TES for the 1st time – R measurement matching expectations– Able to drop most TESs in transition, working on understanding parasitic power

200 um x 50 um TES

40fW bias power

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• Noise– Observed low noise that matches with expected noise level– Clean spectrum with helium battery

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Superconducting

Above transition

In transition

TES measurements

• Time constant– Stepped voltage bias to measure time constant– Observed exponential response - working on understanding results– Upgrading SQUID readout system and DAQ for faster measurement

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TES measurements

Normal

Deep in transition

Superconducting Resonators

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Where multiplexing would help?

Signal type Energy Propagation time scale Collection efficiency

Crystal athermal phonon O(10) meV O(10) ~ O(100) us Prop to (sensor coverage)-1

Sensor efficiency (QET), Surface down-conversion (Defects/dead area)

Crystal (GaAs) IR photon 900 meV O(10) us (or instant) Absorber (or sensor) coverage

He phonon / roton (Quantum evaporation)

~ 1 meV( O(10) meV )

~ 1 ms Surface down-conversion, QE efficiency, Surface absorption gain...

He IR photon ~ 1 eV O(10) us (or instant) Absorber (or sensor) coverage

He UV photon 16eV O(10) us (or instant) Absorber (or sensor) coverage

Triplate state He*2 16eV ~ 10 ms, v = 2 m/s Absorber (or sensor) coverage

Sensor, AbsorberDetector

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Signal type Energy Propagation time scale Collection efficiency

Crystal athermal phonon O(10) meV O(10) ~ O(100) us Prop to (sensor coverage)-1

Sensor efficiency (QET), Surface down-conversion (Defects/dead area)

Crystal (GaAs) IR photon 900 meV O(10) us (or instant) Absorber (or sensor) coverage

He phonon / roton (Quantum evaporation)

~ 1 meV( O(10) meV )

~ 1 ms Surface down-conversion, QE efficiency, Surface adsorption gain...

He IR photon ~ 1 eV O(10) us (or instant) Absorber (or sensor) coverage

He UV photon 16eV O(10) us (or instant) Absorber (or sensor) coverage

Triplate state He*2 16eV O(10) ms, v = 2 m/s Absorber (or sensor) coverage

Integration mode: Individual energy quanta non resolvable. Optimal signal bandwidth should match with signal propagation time.

Counting mode: Individual energy quanta resolvable. Localized signal. Signal bandwidth defined by sensor bandwidth. Multi-channel & multiplexing will improve SNR.

Single channel sensor energy threshold: O(10) meV

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An example of SPICE TES optimization

The detector energy resolution:

If the single TES channel is divided into n small channels, for each small channel:G’ = G/n, 𝜏sensor’ = C’/G’ = 𝜏sensor

Summing all channels together, 𝜎E_total’ = sqrt(n) 𝜎E’ = 𝜎E

But, if the event energy is localized in one single channel: 𝜎E_total’ = 𝜎E’ = 𝜎E/sqrt(n)

Equivalent to divide the active detector volume into multiple small crystals. Similar improvement due to timing (𝜏sensor+𝜏collect→𝜏sensor’) applies. Both built on the assumption that individual energy quanta are resolvable in time and location.

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Where multiplexing would help?High energy (>100 meV) quanta with definitive energy:

Photons (IV, UV) and He2* triplet states direct absorption in sensors.

Could reach with a little jump? He adsorption energy: 40 meV.

Multiplexing will allow large sensor coverage and small individual pixels. Small pixels can improve the energy resolution of each pixel, satisfying the single quantum resolution requirement.

Require detailed investigation into all sensor technology candidates.

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TES with RF multiplexing, MKIDs

TES noise dominated by thermal fluctuation noise (TFN). Energy resolution ~ NEP*sqrt(𝜏)𝜏 ~ C/G

TES array with resonator coupling for RF multiplexing

Microwave kinetic inductance detector (MKIDs)

The Microwave SQUID Multiplexer, thesis by J. Mates

MKIDs noise dominated by quasiparticle generation-recombination (g-r) noise.Energy resolution ~ NEP*sqrt(𝜏)𝜏 =

Phys. Rev. B 15, 3567 (1977)

Noise performance of the multiplexing circuit:Learning in progress. 16

Multiplexing readout

The RF circuit will be characterized with VNA first.

Also exploring Sunil’s group’s setup

SMuRF (SLAC Microresonator Radio Frequency), provided by SLAC. 1809.03689.pdf (arxiv.org)FPGA based. 4000 channels between 4 to 8 GHz.Developed for TES arrays

GroundBird readout systemAn CMB experiment with MKIDs

120 channels between 4 to 8 GHz.Developed for MKIDs.Ready to assemble & test.

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Current developments on RF devices

Experiment

Preparing the readout electronics

Chip-level resonator design

Design and layout chips with desirable performance.

Example of a resonator design

Test environment

Study the resonance/interference of the device with the mounting box. Design the mounting structures inside the dilution fridge.

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Conclusion

We achieved a very clean system for the TES sample characterization. We are actively working on understanding and fixing a few remaining issues in the system.

We are preparing the readout electronics for RF sensors. Meanwhile, we are actively investigating the possible applications of TES RF multiplexing and MKIDs in the TESSERACT detectors.

Please let us know if you have any sensors that want to be tested!

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