High optical efficiency and photon noise limited sensitivity of microwave kinetic inductance detectors using phase readout

Janssen, R. M. J.; Baselmans, J. J. A.; Endo, Akira; Ferrari, L.; Yates, S. J. C.; Baryshev, A.; Klapwijk, T. M.

doi:10.1063/1.4829657

Cited by 77 publications

(100 citation statements)

References 17 publications

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“…Therefore the 350 GHz radiation responsivity δx/δP opt (where x is either amplitude or phase response) is expected to be proportional to the square root of the absorbed power δx/δP opt ∝ P −1/2 opt . These dependences were recently verified both for hybrid NbTiN/Al as well as and for the all-Al KIDs [3,4]. A spurious contribution in the phase response (shown in the inset in Fig.…”

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confidence: 81%

“…In the conventional response the responsivity of a KID decreases with the increase of radiation power due to the reduction in life time of quasiparticles at higher quasiparticle densities. This has been clearly shown for both hybrid NbTiN/Al [3] and all-Al [4] KIDs. In contrast, the TiN KIDs reported in this paper become more responsive at higher radiation powers, as shown in Fig.…”

mentioning

confidence: 81%

“…The same experimental setup is described in more detail by Janssen et al [3] and by de Visser et al [4]. A schematic picture of the experimental setup and device is shown in Fig.…”

mentioning

confidence: 97%

“…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.…”

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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: 81%

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confidence: 81%

“…The same experimental setup is described in more detail by Janssen et al [3] and by de Visser et al [4]. A schematic picture of the experimental setup and device is shown in Fig.…”

mentioning

confidence: 97%

mentioning

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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“…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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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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Superconducting Coplanar Waveguide Filters for Submillimeter Wave On-Chip Filterbank Spectrometers

et al. 2016

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We show the first experimental results which prove that superconducting NbTiN coplanar–waveguide resonators can achieve a loaded Q factor in excess of 800 in the 350 GHz band. These resonators can be used as narrow band pass filters for on-chip filter bank spectrometers for astronomy. Moreover, the low-loss coplanar waveguide technology provides an interesting alternative to microstrip lines for constructing large scale submillimeter wave electronics in general.

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High optical efficiency and photon noise limited sensitivity of microwave kinetic inductance detectors using phase readout

Cited by 77 publications

References 17 publications

Anomalous response of superconducting titanium nitride resonators to terahertz radiation

Anomalous response of superconducting titanium nitride resonators to terahertz radiation

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

Superconducting Coplanar Waveguide Filters for Submillimeter Wave On-Chip Filterbank Spectrometers

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