Low-Mass Dark Matter Searches Using Quantum Sensing and Readout with MKIDs and Paramps Ritoban Basu Thakur on behalf of Golwala-group New Directions in the Search for Light Dark Matter Particles 2019/06/06
Overview Detector requirements for various detection channels Kinetic inductance detector basics KID-based architectures for different science goals and expected energy resolutions Small detectors focused on energy resolution for low-mass reach (< GeV, << GeV) Large detectors focused on ER/NR rejection and position reconstruction for neutrino floor reach at 0.5-5 GeV Progress to date and plans With thanks to: SuperCDMS Pyle, Zurek, Kurinsky, McKinsey et al 2 Basu Thakur/Golwala New Directions in Searches for Light DM
Rapid Introduction
Motivation for Small Sub-eV 10 − 10 Stellar constraints Resolution Detectors Direct detection constraints dark photon absorption M 10 − 12 o Al SC l Current technologies ~1 eV threshold e c u l e s MeV thermal relics, eV dark photons κ 10 − 14 phonon Need new technologies to access excitation keV thermal relics, meV dark photons! i S Ge 10 − 16 e � Dirac material excitation Sharp targets due to simplicity: 1 kg-yr, Sapphire 1 kg-yr, GaAs same diagrams for annih. and scatt. 10 − 18 10 − 3 10 − 2 10 − 1 10 0 10 1 10 2 no accidental cancellations m A � [eV] DM-electron scattering (light mediator) DM-nucleon scattering 10 − 34 10 � 32 10 � 33 ω > 1 meV BBN 10 − 35 Xenon10 ω > 25 meV 10 � 34 Stellar bounds ω > 50 meV 10 − 36 10 � 35 ω > 75 meV Al SC 10 � 36 10 − 37 Freeze-in Al 2 O 3 10 � 37 σ e [cm 2 ] σ n (cm 2 ) LBECA 10 − 38 10 � 38 H e ( r m o t a u l l l t SENSEI-100g i 10 � 39 t i n p i h c s o 10 − 39 n o n DAMIC-1K ) 10 � 40 SuperCDMS G2 n 10 − 40 10 � 41 o n o h p 10 � 42 ZrTe 5 10 − 41 10 � 43 GaAs 10 − 42 10 � 44 Al 2 O 3 Dark photon mediator m A 0 ⌧ keV Al 2 O 3 (mod) 10 � 45 10 − 43 10 � 3 10 � 2 10 � 1 10 0 10 1 10 2 10 3 10 1 10 2 10 3 m χ [MeV] m X (keV) 4 Basu Thakur/Golwala New Directions in Searches for Light DM
Basics of Kinetic Inductance Detectors Frequency sub-meV IQ Mixers Synthesizers pair- I breaking Q energy Cryostat ... ... Mazin Day Superconductors have an AC inductance due to inertia of Cooper pairs alternately, due to magnetic energy stored in screening supercurrent Changes when Cooper pairs broken by energy, creating quasiparticles (qps) Sense the change by monitoring a resonant circuit Key point: superconductors provide very high Q (Q i > 10 7 achieved), so thousands of such resonators can be monitored with a single feedline enormous cryogenic multiplex technology relative to existing ones very simple cryogenic readout components 5 Basu Thakur/Golwala New Directions in Searches for Light DM
Basics of Kinetic Inductance Detectors Frequency sub-meV IQ Mixers Synthesizers pair- I breaking Q energy Cryostat ... ... Mazin Day Superconductors have an AC inductance due to inertia of Cooper pairs alternately, due to magnetic energy stored in screening supercurrent Changes when Cooper pairs broken by energy, creating quasiparticles (qps) Sense the change by monitoring a resonant circuit Key point: superconductors provide very high Q (Q i > 10 7 achieved), so thousands of such resonators can be monitored with a single feedline enormous cryogenic multiplex technology relative to existing ones very simple cryogenic readout components 6 Basu Thakur/Golwala New Directions in Searches for Light DM
Detector physics
Quasiparticles to Conductivity Mattis-Bardeen Relations 10 0 MB gives characteristic T and ℏ ω / ∆ = 0.06 10 -5 ℏ 𝜕 / ∆ dependence n qp /(2N 0 Δ ) | | 10 -10 ⇥ ¯ ⇥ ¯ thermally | σ (0) | = 4 σ 1 n qp 1 h ω ⇤ h ω ⇤ sinh K 0 generated π 2 N 0 ∆ ⌦ 2 kT 2 kT 2 π kT 10 -15 quasiparticle ∆ ⇥ ¯ ⌅ ⇤⇧ ↵ density n qp 2 ∆ ⇥ − ¯ h ω ⇤ h ω σ 2 | σ (0) | = 1 − 1 + π kT exp I 0 10 -20 10 0 2 N 0 ∆ 2 kT 2 kT ⇥ ¯ ⇥ ¯ | | Recall σ (0) = j σ n ( πΔ /h ν ) (0) ) � 2 4 1 ⇤ ⇤ ∆ � 10 -5 conductivity fully 2 N 0 ∆ ∂ ( σ 1 / | σ (0) | ) � = 2 N 0 ∆ | σ (0) | = 4 σ 1 [ σ - σ (0)]/| σ (0)| � inductive � ∂ n qp n qp π quiescent fractional � T at T = 0 10 -10 conductivity deviation � 2 N 0 ∆ ∂ ( σ 2 / | σ (0) | ) = 2 N 0 ∆ σ 2 − σ 2 (0) � from T=0 value = � ∂ n qp n qp | σ (0) | � T 10 -15 real part Key features -(imaginary part) 10 -20 5 fractional [2N 0 Δ /n qp ] [ σ - σ (0)]/| σ (0)| Quiescent n qp exponentially suppressed = [2N 0 Δ ] ∂ ( σ /| σ (0)|)/ ∂ n qp real part responsivity 4 -(imaginary part) as T decreases* 3 * as long as no anomalous qp recombination physics 2 weak T -dependence * as long as no anomalous qp creation 1 Responsivity only weakly T -dependent 0 (not exponential!) 0.1 T/T c 8 Basu Thakur/Golwala New Directions in Searches for Light DM
Nonidealities: Quasiparticle Density and Lifetime Limits asymptotic regime; limiting excess qp density n ∗ , or something else? Quasiparticle response related to disorder? (Barends et al implantation experiment) governed by quasiparticle ≥ δ 10 2 10 3 BCS theory lifetime, observed to as reproduced in Zmuidzinas, ARCMP (2012) follow τ max τ qp = 1 + n qp /n ∗ Ta relaxation time (µs) Al relaxation time (µs) where n ∗ may be a 100 1,000 Barends et al PRL (2008) limiting qp density 10 2 10 1 Ta relaxation time (µs) Al relaxation time (µs) 750 75 Frequently written as 1 1 500 50 = 2 R n qp + τ qp τ max with the recombination 250 25 constant R = (2 n ∗ τ max ) − 1 0 Al f lms 0 0 0.05 0.10 0.15 0.20 0.25 Ta f lms T / T c 10 1 10 0 0.03 0.3 Reduced temperature ( T / T c ) Sets bandwidth over which noise integrated: Lifetime (msec) larger 𝜐 qp is better Many ms lifetimes achievable but perhaps only at Noroozian low readout powers Need to make conservative assumptions about 𝜐 qp to avoid optimistic predictions 9 Basu Thakur/Golwala New Directions in Searches for Light DM devel τ τ §4.2.2
Science: goals & prospects
b) no quasiparticle Small-Detector (gram-scale) Architectures trapping!* 2 cm Goal: detection of sub-eV energies from: 1 g *of the conventional kind with collector >> KID Dark phonon absorption, DM-e scattering, scalar-mediated nucleon scattering at very low recoil energies, directly producing phonons w/o e-h pairs KID Methods: Detection of qp creation in superconducting target via phonon or qp collection (Hochberg, Zhao, Zurek, arXiv:1504.07237) DM-produced phonon Phonons appropriate when 2 ∆ substrate > h ν phonon : phonons insulating propagate quasi-ballistically with long decay times crystal (100 µs - ms: SuperCDMS, Gaitskell thesis w/high RRR Nb) Quasiparticles appropriate when 2 ∆ substrate < h ν phonon : KID phonons cannot propagate, but qp’s can, w/long decay times KID insulator (e.g.: probably Al, other low T superconductors: untested!) qp trap insulator Detection of optical phonon production in polar materials: phonon GaAs (Knapen, Lin, Pyle, Zurek, arXiv:1712.06598) quiescent qp Al 2 O 3 (Griffin, Knapen, Lin, Zurek, arXiv:1807.10291) DM-produced qp Architecture: Single mm-scale KID on gm-scale, few-mm target substrate superconducting crystal Lower-gap superconductor for KID (e.g., AlMn) and/or better amplifiers promise meV-scale resolution 11 Basu Thakur/Golwala New Directions in Searches for Light DM
no quasiparticle trapping! Small-Detector Architecture Characteristic Energy Resolution: Optimistic Prediction r Assume “efficiency factors” all assumed to be unity by design (optimistic) delta-function-like energy deposition χ c = 4 Q 2 qp population dominated by readout power generation r 1 Q i Q c dissipation readout (no TLS noise) Q i χ qp = 1 amplifier noise dominant over g-r noise (T ~ 0.1 T c required) Q i,qp quasiparticle lifetime >> phonon absorption time, τ qp >> τ ph,abs ~ 100 µs τ qp χ BW = 1 optimistic, requires increasing τ qp from ~100 µs τ abs + τ qp Reduce ∆ , T N to get well below eV resolution normal state efficiency of superconducting single-spin qp creation by gap energy density of states readout power resonator effective r η read volume (weighted by s s σ E = 2 ∆ N 0 V r k B T N amplifier noise current 2 ) temperature γ s S 1 ( f r , T qp , ∆ ) Q i,qp η ph αχ c χ qp χ BW ✓ 0 . 3 ◆ s s r η read ◆ ✓ 10 6 0 . 1 ∆ V r T N 1 . 6 σ E = (0 . 9 eV) 10 4 ( µ m) 3 200 µ eV 5 K S 1 ( f r , T qp , ∆ ) η ph p t α Q i,qp 1 mm 2 x 10 nm efficiency for probability for superconductivity ~ aluminum quality factor converting phonon to enter fraction of factor gap due to phonons to qps KID per try inductance quasiparticles due to KI 12 Basu Thakur/Golwala New Directions in Searches for Light DM
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