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13 results on '"Etaki S"'

1. Coupling carbon nanotube mechanics to a superconducting circuit

Author

Schneider, B. H., Etaki, S., van der Zant, H. S. J., and Steele, G. A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity, Physics - Instrumentation and Detectors, Quantum Physics
Abstract

The quantum behaviour of mechanical resonators is a new and emerging field driven by recent experiments reaching the quantum ground state. The high frequency, small mass, and large quality-factor of carbon nanotube resonators make them attractive for quantum nanomechanical applications. A common element in experiments achieving the resonator ground state is a second quantum system, such as coherent photons or superconducting device, coupled to the resonators motion. For nanotubes, however, this is a challenge due to their small size. Here, we couple a carbon nanoelectromechanical (NEMS) device to a superconducting circuit. Suspended carbon nanotubes act as both superconducting junctions and moving elements in a Superconducting Quantum Interference Device (SQUID). We observe a strong modulation of the flux through the SQUID from displacements of the nanotube. Incorporating this SQUID into superconducting resonators and qubits should enable the detection and manipulation of nanotube mechanical quantum states at the single-phonon level.

Published
2012
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2. Discrete-time quadrature feedback cooling of a radio-frequency mechanical resonator

Author

Poot, M., Etaki, S., Yamaguchi, H., and van der Zant, H. S. J.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We have employed a feedback cooling scheme, which combines high-frequency mixing with digital signal processing. The frequency and damping rate of a 2 MHz micromechanical resonator embedded in a dc SQUID are adjusted with the feedback, and active cooling to a temperature of 14.3 mK is demonstrated. This technique can be applied to GHz resonators and allows for flexible control strategies., Comment: To appear in Appl. Phys. Lett

Published
2011
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3. Tunable backaction of a dc SQUID on an integrated micromechanical resonator

Author

Poot, M., Etaki, S., Mahboob, I., Onomitsu, K., Yamaguchi, H., Blanter, Ya. M., and van der Zant, H. S. J.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity
Abstract

We have measured the backaction of a dc superconducting quantum interference device (SQUID) position detector on an integrated 1 MHz flexural resonator. The frequency and quality factor of the micromechanical resonator can be tuned with bias current and applied magnetic flux. The backaction is caused by the Lorentz force due to the change in circulating current when the resonator displaces. The experimental features are reproduced by numerical calculations using the resistively and capacitively shunted junction (RCSJ) model., Comment: Submitted to Phys. Rev. Lett

Published
2010
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4. Superconducting Quantum Interference based Electromechanical Systems

Author

Etaki, S. and Van der Zant, H.S.J.

Subjects
Josephson junctions, Condensed Matter::Superconductivity, Physics::Medical Physics, quantum mechanics, dc SQUID, superconductors, electromechanics
Abstract

Mechanical sensors are essential tools for the detection of small forces. This thesis presents the dc SQUID as a detector for the displacement of embedded micromechanical resonators. The device geometry and basic operating principle are described. The SQUID displacement detector reaches an excellent resolution, a factor of 1.5 below the standard quantum limit: It can detect one-third of a single vibrational quantum in a 129 kHz resonator. We use the high displacement sensitivity to perform feedback cooling of the temperature of the fundamental resonance mode by using a heterodyne discrete-time scheme. The thesis also studies the SQUID backaction: Because of the strong coupling between the SQUID and the resonator, the SQUID exerts forces on the resonator which change the resonator spring constant and damping depending on the current and flux bias of the SQUID. In the final chapter, the entire SQUID is mechanically suspended to form a torsional resonator. In this geometry, the backaction becomes so strong that the resonators goes into self-sustained oscillation. In conclusion, the results in this thesis show that the dc SQUID is an excellent displacement detector for micro-and nanomechanical resonators, but also that the SQUID-resonator interaction strongly influences the resonator dynamics.

Published
2012

5. Superconducting Quantum Interference based Electromechanical Systems

Author

Etaki, S. (author) and Etaki, S. (author)

Abstract

Mechanical sensors are essential tools for the detection of small forces. This thesis presents the dc SQUID as a detector for the displacement of embedded micromechanical resonators. The device geometry and basic operating principle are described. The SQUID displacement detector reaches an excellent resolution, a factor of 1.5 below the standard quantum limit: It can detect one-third of a single vibrational quantum in a 129 kHz resonator. We use the high displacement sensitivity to perform feedback cooling of the temperature of the fundamental resonance mode by using a heterodyne discrete-time scheme. The thesis also studies the SQUID backaction: Because of the strong coupling between the SQUID and the resonator, the SQUID exerts forces on the resonator which change the resonator spring constant and damping depending on the current and flux bias of the SQUID. In the final chapter, the entire SQUID is mechanically suspended to form a torsional resonator. In this geometry, the backaction becomes so strong that the resonators goes into self-sustained oscillation. In conclusion, the results in this thesis show that the dc SQUID is an excellent displacement detector for micro-and nanomechanical resonators, but also that the SQUID-resonator interaction strongly influences the resonator dynamics., Quantum Nanoscience, Applied Sciences

Published
2012

6. Discrete-time quadrature feedback cooling of a radio-frequency mechanical resonator

Author

Poot, M. (author), Etaki, S. (author), Yamaguchi, H. (author), Van der Zant, H.S.J. (author), Poot, M. (author), Etaki, S. (author), Yamaguchi, H. (author), and Van der Zant, H.S.J. (author)

Abstract

We have employed a feedback cooling scheme, which combines high-frequency mixing with digital signal processing. The frequency and damping rate of a 2 MHz micromechanical resonator embedded in a dc SQUID are adjusted with the feedback, and active cooling to a temperature of 14.3 mK is demonstrated. This technique can be applied to GHz resonators and allows for flexible control strategies., QN/Quantum Nanoscience, Applied Sciences

Published
2011
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7. Tunable Backaction of a DC SQUID on an Integrated Micromechanical Resonator

Author

Poot, M. (author), Etaki, S. (author), Mahboob, I. (author), Onomitsu, K. (author), Yamaguchi, H. (author), Blanter, Y.M. (author), Van der Zant, H.S.J. (author), Poot, M. (author), Etaki, S. (author), Mahboob, I. (author), Onomitsu, K. (author), Yamaguchi, H. (author), Blanter, Y.M. (author), and Van der Zant, H.S.J. (author)

Abstract

We have measured the backaction of a dc superconducting quantum interference device (SQUID) position detector on an integrated 1 MHz flexural resonator. The frequency and quality factor of the micromechanical resonator can be tuned with bias current and applied magnetic flux. The backaction is caused by the Lorentz force due to the change in circulating current when the resonator displaces. The experimental features are reproduced by numerical calculations using the resistively and capacitively shunted junction model., Kavli Institute of Nanoscience, Applied Sciences

Published
2010
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13. Fast and efficient photodetection in nanoscale quantum-dot junctions.

Author

Prins F, Buscema M, Seldenthuis JS, Etaki S, Buchs G, Barkelid M, Zwiller V, Gao Y, Houtepen AJ, Siebbeles LD, and van der Zant HS

Subjects
Colloids chemistry, Electrodes, Electrons, Light, Microscopy, Confocal methods, Optics and Photonics, Photochemistry methods, Time Factors, Nanotechnology methods, Quantum Dots
Abstract

We report on a photodetector in which colloidal quantum dots directly bridge nanometer-spaced electrodes. Unlike in conventional quantum-dot thin film photodetectors, charge mobility no longer plays a role in our quantum-dot junctions as charge extraction requires only two individual tunnel events. We find an efficient photoconductive gain mechanism with external quantum efficiencies of 38 electrons-per-photon in combination with response times faster than 300 ns. This compact device-architecture may open up new routes for improved photodetector performance in which efficiency and bandwidth do not go at the cost of one another.

Published
2012
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