Co-sputtered MoRe thin films for carbon nanotube growth-compatible superconducting coplanar resonators

Circuit QED techniques have been instrumental to manipulate and probe with exquisite sensitivity the quantum state of superconducting quantum bits coupled to microwave cavities. Recently, it has become possible to fabricate new devices where the superconducting quantum bits are replaced by hybrid mesoscopic circuits combining nanoconductors and metallic reservoirs. This mesoscopic QED provides a new experimental playground to study the light-matter interaction in electronic circuits. Here, we present the experimental state of the art of Mesoscopic QED and its theoretical description. A first class of experiments focuses on the artificial atom limit, where some quasiparticles are trapped in nanocircuit bound states. In this limit, the Circuit QED techniques can be used to manipulate and probe electronic degrees of freedom such as confined charges, spins, or Andreev pairs. A second class of experiments consists in using cavity photons to reveal the dynamics of electron tunneling between a nanoconductor and fermionic reservoirs. For instance, the Kondo effect, the charge relaxation caused by grounded metallic contacts, and the photo-emission caused by voltage-biased reservoirs have been studied. The tunnel coupling between nanoconductors and fermionic reservoirs also enable one to obtain split Cooper pairs, or Majorana bound states. Cavity photons represent a qualitatively new tool to study these exotic condensed matter states.

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“…In this diagonal case, it is possible to reduce the number of Green's function in expression (67) by using the identity…”

Section: B Effective Admittance Of a Single Quantum Dot With Normal mentioning

confidence: 99%

Cavity QED with hybrid nanocircuits: from atomic-like physics to condensed matter phenomena

Cottet¹,

Dartiailh²,

Desjardins³

et al. 2017

J. Phys.: Condens. Matter

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“…While our thin film deposition via co‐sputtering from two sources has the advantage of adjustable alloy composition (), other published results using pre‐alloyed sputter targets display significantly higher quality factors (). Given our excellent results using niobium, we can exclude problems with substrate, lithography, and detection circuitry.…”

Section: Discussionmentioning

confidence: 96%

“…The resonance frequency

f_{r}

decreases strongly with temperature, as does the total quality factor. A quantitative description of this is given by the so‐called Mattis–Bardeen theory . The temperature dependence of

f_{r}

and

Q_{i}

can be expressed as

\frac{f_{normalr} - f_{0}}{f_{0}} = \frac{α_{0}}{2} \frac{δ σ_{2}}{σ_{2}},

δ (\frac{1}{Q_{i}}) = α_{0} \frac{δ σ_{1}}{σ_{2}},

with

f_{0}

and

α_{0}

as the zero‐temperature limit of resonance frequency and kinetic inductance fraction.…”

Section: Temperature Dependence Of Resonator Propertiesmentioning

confidence: 99%

“…

σ_{1}

and

σ_{2}

are the real and imaginary part of the complex conductivity

σ

of the device. We use analytical approximations for both parts of the complex conductivity in the low temperature limit , containing the temperature dependent BCS energy gap and the normal state conductivity.…”

Section: Temperature Dependence Of Resonator Propertiesmentioning

confidence: 99%

“…For high‐frequency experiments, where a suspended carbon nanotube is to be coupled to, e.g., a coplanar microwave resonator, a physically and chemically stable metal is required that remains superconducting even after incorporation of carbon and possible segregation processes during the high‐temperature step. We characterize coplanar waveguide resonators fabricated from the co‐sputtered molybdenum–rhenium alloy

{Mo}_{20} {Re}_{80}

(). Even after CVD clear resonant behavior is observed.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Towards carbon nanotube growth into superconducting microwave resonator geometries

Blien

Götz

Stiller

et al. 2016

Physica Status Solidi (b)

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The in‐place growth of suspended carbon nanotubes facilitates the observation of both unperturbed electronic transport spectra and high‐Q vibrational modes. For complex structures integrating, e.g., superconducting rf elements on‐chip, selection of a chemically and physically resistant material that survives the chemical vapor deposition (CVD) process provides a challenge. We demonstrate the implementation of molybdenum–rhenium coplanar waveguide resonators that exhibit clear resonant behavior at cryogenic temperatures even after having been exposed to nanotube growth conditions. The properties of the MoRe devices before and after CVD are compared to a reference niobium device. (a) Schematic of the CVD growth environment; a metal thin film is exposed to a CH4 /H2 atmosphere at 850 °C. (b) MoRe coplanar waveguides still display superconductivity after this treatment, with clear resonant behavior of a λ/4 structure.

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Quartz Tuning‐Fork Based Carbon Nanotube Transfer into Quantum Device Geometries

Blien

Steger

Albang

et al. 2018

Physica Status Solidi (b)

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With the objective of integrating single clean, as‐grown carbon nanotubes into complex circuits, we have developed a technique to grow nanotubes directly on commercially available quartz tuning forks using a high‐temperature chemical vapor deposition process. Multiple straight and aligned nanotubes bridge the >100 µm gap between the two tips. The nanotubes are then lowered onto contact electrodes, electronically characterized in situ, and subsequently cut loose from the tuning fork using a high current. First quantum transport measurements of the resulting devices at cryogenic temperatures display Coulomb blockade characteristics.

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Co-sputtered MoRe thin films for carbon nanotube growth-compatible superconducting coplanar resonators

Cited by 11 publications

References 40 publications

Cavity QED with hybrid nanocircuits: from atomic-like physics to condensed matter phenomena

Cavity QED with hybrid nanocircuits: from atomic-like physics to condensed matter phenomena

Towards carbon nanotube growth into superconducting microwave resonator geometries

Quartz Tuning‐Fork Based Carbon Nanotube Transfer into Quantum Device Geometries

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