Photon-noise limited sensitivity in titanium nitride kinetic inductance detectors

Hubmayr, Johannes; Beall, James A.; Becker, D.; Cho, H. M.; Devlin, Mark J.; Dober, Bradley; Groppi, Christopher; Hilton, G. C.; Irwin, K. D.; Li, D.; Mauskopf, Philip Daniel; Pappas, David P.; Lanen, Jeff Van; Vissers, Michael; Wang, Yiwen; Wei, L. F.

doi:10.1063/1.4913418

Cited by 72 publications

(77 citation statements)

References 26 publications

(29 reference statements)

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“…3. No sign of photon noise was observed in these experiments in contrast to recent experiments in which photon noise was reported [24], which may be related to different photon-power densities [25].…”

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confidence: 54%

“…Since the noise is independent of radiation power, the optical NEP is also a strong function of the radiation power. At high radiation powers, comparable to the incident radiation in ground-based telescopes, the optical NEP approaches the requirements for ground-based instruments (recently achieved by increasing the received power per unit volume of the KIDs [24]). Despite the fact that the TiN is a good absorber, the difference between the electrical NEP and the measured optical NEP at the lowest radiation power is a factor of 100.…”

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confidence: 99%

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Anomalous response of superconducting titanium nitride resonators to terahertz radiation

Bueno

Coumou

Zheng

et al. 2014

Applied Physics Letters

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We present an experimental study of KIDs fabricated of atomic layer deposited TiN films, and characterized at radiation frequencies of 350 GHz. The responsivity to radiation is measured and found to increase with increasing radiation powers, opposite to what is expected from theory and observed for hybrid niobium titanium nitride / aluminium (NbTiN/Al) and all-aluminium (allAl) KIDs. The noise is found to be independent of the level of the radiation power. The noise equivalent power (NEP) improves with higher radiation powers, also opposite to what is observed and well understood for hybrid NbTiN/Al and all-Al KIDs. We suggest that an inhomogeneous state of these disordered superconductors should be used to explain these observations. Superconducting resonators have been proposed as kinetic inductance detectors (KIDs) for sensitive multipixel radiation detection [1]. Antenna-coupled hybrid niobium titanium nitride / aluminium (NbTiN/Al) KIDs [2,3] and all-aluminium (all-Al) [4] have shown generationrecombination noise and photon noise limited performance. KIDs can also be constructed as lumped element kinetic inductance detectors (LEKIDs) [5] in which the KID is arranged as a photon absorbing area matched to free space. Aluminium LEKIDs have also shown generation-recombination and photon noise limited performance [6]. However, the low normal-state resistivity of Al makes the design of the absorber for very high frequency radiation complex. Therefore, superconductors with a high normal state resistivity have recently become of particular interest [9].A figure of merit F to optimize the responsivity of KIDs is defined as, with α sc the kinetic inductance fraction, τ the quasiparticle recombination time, Q i the internal quality factor, F res the resonance frequency, N (0) is the single spin electron density of states at the Fermi level, and V the volume of the KID. For example, Al KIDs have a long quasiparticle recombination time (a few milliseconds) and high internal quality factors (above one million), but their kinetic inductance fraction is low and their volume large.Superconducting materials with a high resistivity in the normal-state are promising because of their high quality factor and a long enough relaxation time. The high normal resistance implies a large sheet inductance, resulting in a large kinetic inductance fraction, which lowers the KID volume. The high surface impedance also eases matching to free space and optimises the photon absorption. Given the high quality NbTiN resonators pioneered by Barends et al. [7,8], titanium nitride (TiN) has been proposed, because it has the previously mentioned properties in addition to a tuneable critical temperature, which facilitates a relatively long quasiparticle lifetime [9]. Currently, several groups are studying the implementation of TiN KID devices and instruments [10][11][12][13][14]. However, a material like TiN has also drawn the attention of the condensed matter physics community, interested in the disorder-induced superconductorto-insulator transitio...

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confidence: 99%

Anomalous response of superconducting titanium nitride resonators to terahertz radiation

Bueno

Coumou

Zheng

et al. 2014

Applied Physics Letters

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“…Here, P opt is the applied optical power and ∆ the band gap of the LED. This linear optical response for TiN MKID has been reported earlier in submillimeter wave measurement and the underlying physics is now an active area of research [11]. It is interesting to observe the linear response of TiN MKID to optical photons whose energy is 3 orders of magnitude higher than mm-wave photons.…”

Section: Methodsmentioning

confidence: 71%

“…For example, we are developing feed-horn coupled dual-polarization sensitive MKID [11] arrays made from titanium-nitride/titanium (TiN/Ti) multilayer films with target T c ≈ 1.4 K for the BLAST-TNG experiment [12]. We have made a 90 pixel hexagonal close-packed TiN MKID array on a 76.2 mm intrinsic Si wafer to study the wafer uniformity ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Cryogenic LED pixel-to-frequency mapper for kinetic inductance detector arrays

Liu

Guo

Wang

et al. 2017

Journal of Applied Physics

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We present a cryogenic wafer mapper based on light emitting diodes (LEDs) for spatial mapping of a large microwave kinetic inductance detector (MKID) array. In this scheme, an array of LEDs, addressed by DC wires and collimated through horns onto the detectors, is mounted in front of the detector wafer. By illuminating each LED individually and sweeping the frequency response of all the resonators, we can unambiguously correspond a detector pixel to its measured resonance frequency. We have demonstrated mapping a 76.2 mm 90-pixel MKID array using a mapper containing 126 LEDs with 16 DC bias wires. With the frequency to pixel-position correspondence data obtained by the LED mapper, we have found a radially position-dependent frequency non-uniformity 1.6% over the 76.2 mm wafer. Our LED wafer mapper has no moving parts and is easy to implement. It may find broad applications in superconducting detector and quantum computing/information experiments.

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“…MKIDs are photon noise limited for various frequencies [10][11][12][13][14][15] . The level of experimental detail that has now been achieved 13,16,17 calls for a more detailed understanding of the absorption of radiation.…”

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confidence: 99%

The non-equilibrium response of a superconductor to pair-breaking radiation measured over a broad frequency band

Visser

Yates

Guruswamy

et al. 2015

Applied Physics Letters

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We have measured the absorption of terahertz radiation in a BCS superconductor over a broad range of frequencies from 200 GHz to 1.1 THz, using a broadband antenna-lens system and a tantalum microwave resonator. From low frequencies, the response of the resonator rises rapidly to a maximum at the gap edge of the superconductor. From there on the response drops to half the maximum response at twice the pairbreaking energy. At higher frequencies, the response rises again due to trapping of pair-breaking phonons in the superconductor. In practice this is the first measurement of the frequency dependence of the quasiparticle creation efficiency due to pair-breaking in a superconductor. The efficiency, calculated from the different nonequilibrium quasiparticle distribution functions at each frequency, is in agreement with the measurements.In a superconductor at low temperature, most of the electrons are bound in Cooper pairs. These pairs can be broken into quasiparticles by absorbing photons with an energy larger than the binding energy. This mechanism is frequently used to detect submillimetre and terahertz radiation using conventional superconductors such as aluminium. Pair-breaking detectors are usually assumed to measure the number of quasiparticles created by the absorbed radiation. The observable that measures the number of quasiparticles varies from the complex conductivity for microwave kinetic inductance detectors 1 (MKIDs), the current through a tunnel junction 2 to the capacitance of a small superconducting island 3 . These observables are mainly sensitive to quasiparticles with an energy close to the gap energy of the superconductor, ∆. The working principle of these detectors is usually explained in terms of an effective number of quasiparticles which is maintained by a balance between the radiation power and electron-phonon interaction (recombination) 4 . To convert the power (P ) into a number of quasiparticles (N qp ), the quasiparticle creation efficiency η pb is introduced, which compares the actual N qp with the maximum possible N qp when all created quasiparticles would have an energy ∆. Since Cooper pairs have a binding a) Electronic mail: p.j.devisser@tudelft.nl; Current address: Department of Quantum Matter Physics, University of Geneva, Geneva 1211, Switzerland energy of 2∆, a photon with an energy in between 2∆ and 4∆ can still only create two quasiparticles. The rest of the energy is lost through electron-phonon scattering, hence η pb < 1. For higher energies η pb depends on the phonon trapping factor, which determines whether high energy phonons are directly lost or can break an additional pair. η pb is therefore not an efficiency in the sense that photons are lost, but it reduces the detector responsivity. MKIDs are superconducting microwave resonators which sense the number of quasiparticles through the complex conductivity of the superconductor. The phase response (θ) of such a resonator can be approximated bywhere σ 2 is the imaginary part of the complex conductivity. For the last propo...

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Photon-noise limited sensitivity in titanium nitride kinetic inductance detectors

Cited by 72 publications

References 26 publications

Anomalous response of superconducting titanium nitride resonators to terahertz radiation

Anomalous response of superconducting titanium nitride resonators to terahertz radiation

Cryogenic LED pixel-to-frequency mapper for kinetic inductance detector arrays

The non-equilibrium response of a superconductor to pair-breaking radiation measured over a broad frequency band

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