Decay Times of Optical Pulses for Aluminum CPW KIDs

Fyhrie, Adalyn; Day, Peter; Glenn, J.; Leduc, H. G.; McKenney, Christopher; Perido, Joanna; Žmuidzinas, J.

doi:10.1007/s10909-020-02377-7

Cited by 7 publications

(7 citation statements)

References 14 publications

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“…Impurities and disorder in superconductors are known to reduce the recombination time at low temperatures [10,11] and can fundamentally change the relation between the quasiparticle number and recombination time. The low-temperature recombination time is typically limited from tens of microseconds [11,12] to milliseconds [2,13], depending on the material. However, these experiments only measure the recombination time from a nonequilibrium pulse decay, or suffer from excess quasiparticles.…”

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confidence: 99%

“…Correspondingly, the intrinsic quasiparticle recombination lifetime (τ qp ) goes exponentially up with decreasing temperature [3]. In practice, it is typically found that the quasiparticle lifetime saturates for low temperatures, to tens of microseconds [4,5] or milliseconds [6,7], depending on the material. For Al superconducting resonators, non-equilibrium quasiparticles have been put forward as a cause [6], which are thought to be generated by stray light [8], cosmic rays [9] or microwave read power [10,11], and limits the sensitivity of Microwave Kinetic Inductance Detectors (MKIDs) [12].…”

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confidence: 99%

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Strong reduction of quasiparticle fluctuations in a superconductor due to decoupling of the quasiparticle number and lifetime

et al. 2021

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We measure temperature-dependent quasiparticle fluctuations in a small Al volume, embedded in a NbTiN superconducting microwave resonator. The resonator design allows for readout close to equilibrium. By placing the Al film on a membrane, we enhance the fluctuation level and separate quasiparticle effects from phonon effects. When lowering the temperature, the recombination time saturates and the fluctuation level reduces by a factor ∼100. From this we deduce that the number of free quasiparticles is still thermal. Therefore, the theoretical, inverse relation between the quasiparticle number and recombination time is invalid in this experiment. This is consistent with quasiparticle trapping, where on-trap recombination limits the observed quasiparticle lifetime.

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confidence: 99%

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Strong reduction of quasiparticle fluctuations in a superconductor due to decoupling of the quasiparticle number and lifetime

et al. 2021

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“…pulse shape that are independent of energy. Some suspected sources of these energy-independent shape changes are phonon loss into the substrate 22 and a position-dependent detector response. 23,24 Further improvements to the detectors themselves are likely required before the full benefits of using this analysis technique can be realized.…”

Section: Optical To Near-ir Mkid Data Analysismentioning

confidence: 99%

Improving the energy resolution of photon counting Microwave Kinetic Inductance Detectors using principal component analysis

Miller,

Zobrist,

Ulbricht

et al. 2021

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We develop a photon energy measurement scheme for single photon counting Microwave Kinetic Inductance Detectors (MKIDs) that uses principal component analysis (PCA) to measure the energy of an incident photon from the signal ("photon pulse") generated by the detector. PCA can be used to characterize a photon pulse using an arbitrarily large number of features and therefore PCA-based energy measurement does not rely on the assumption of an energy-independent pulse shape that is made in standard filtering techniques. A PCA-based method for energy measurement is especially useful in applications where the detector is operating near its saturation energy and pulse shape varies strongly with photon energy. It has been shown previously that PCA using two principal components can be used as an energy-measurement scheme. We extend upon these ideas and develop a method for measuring the energies of photons by characterizing their pulse shapes using any number of principal components and any number of calibration energies. Applying this technique with 50 principal components, we show improvements to a previouslyreported energy resolution for Thermal Kinetic Inductance Detectors (TKIDs) from 75 eV to 43 eV at 5.9 keV. We also apply this technique with 50 principal components to data from an optical to near-IR MKID and achieve energy resolutions that are consistent with the best results from existing analysis techniques.

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“…Figure 1 presents the parameters of an aluminum MKID as a function of T c , where we display the plots of the device temperature at approximately 0.3 K. They are sensitive to T c . Various previous studies have used different T c , with the deviation being approximately 10% 9,13,14 . Understanding the reason of this difference is a recent research topic, e.g., Fyhrie et al 13 discusses the relation between T c and film thickness.…”

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confidence: 99%

“…Various previous studies have used different T c , with the deviation being approximately 10% 9,13,14 . Understanding the reason of this difference is a recent research topic, e.g., Fyhrie et al 13 discusses the relation between T c and film thickness. Monitoring the transmittance of the readout microwaves with the device temperature variation is a conventional method to measure the T c of an MKID 15,16 .…”

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A method to measure superconducting transition temperature of microwave kinetic inductance detector by changing power of readout microwaves

et al. 2020

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A microwave kinetic inductance detector (MKID) is a cutting-edge superconducting detector, and its principle is based on a superconducting resonator circuit. The superconducting transition temperature (Tc) of the MKID is an important parameter because various MKID characterization parameters depend on it. In this paper, we propose a method to measure the Tc of the MKID by changing the applied power of the readout microwaves. A small fraction of the readout power is deposited on the MKID, and the number of quasiparticles in the MKID increases with this power. Furthermore, the quasiparticle lifetime decreases with the number of quasiparticles. Therefore, we can measure the relation between the quasiparticle lifetime and the detector response by rapidly varying the readout power. From this relation, we evaluate the intrinsic quasiparticle lifetime. This lifetime is theoretically modeled by Tc, the physical temperature of the MKID device, and other known parameters. We obtain Tc by comparing the measured lifetime with that acquired using the theoretical model. Using an MKID fabricated with aluminum, we demonstrate this method at a 0.3 K operation. The results are consistent with those obtained by Tc measured by monitoring the transmittance of the readout microwaves with the variation in the device temperature. The method proposed in this paper is applicable to other types, such as a hybrid-type MKID.

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Decay Times of Optical Pulses for Aluminum CPW KIDs

Cited by 7 publications

References 14 publications

Strong reduction of quasiparticle fluctuations in a superconductor due to decoupling of the quasiparticle number and lifetime

Strong reduction of quasiparticle fluctuations in a superconductor due to decoupling of the quasiparticle number and lifetime

Improving the energy resolution of photon counting Microwave Kinetic Inductance Detectors using principal component analysis

A method to measure superconducting transition temperature of microwave kinetic inductance detector by changing power of readout microwaves

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