11 research outputs found
Gradient Field Transduction of Nanomechanical Resonators
Das Forschungsgebiet nanomechanischer Systeme betrachtet die Bewegung von Strukturen, deren Länge in mindestens einer Richtung deutlich unter einem Mikrometer liegt. Meist werden dabei Auslenkungen untersucht, die in der Nähe einer mechanischen Resonanz angetrieben werden. Das wissenschaftliche Interesse an solchen Strukturen hat mehrere Gründe: aufgrund der kleinen Masse und oftmals geringen Dämpfung (d.h. hohe Güte) reagieren solche nanomechanischen Systeme sehr empfindlich auf Änderungen ihrer Umgebung oder ihrer eigenen Eigenschaften wie etwa ihrer Masse. Die große Vielfalt der nanomechanischen Systeme erlaubt die Kopplung an verschiedenste physikalische Größen wie (Umgebungs-)Druck, Licht, elektrische/magnitische Felder. Dies ermöglicht, die Wechselwirkung selbst zu untersuchen oder entsprechende Änderungen empfindlich zu detektieren.
Im Rahmen der vorliegenden Arbeit wurde die Resonator Bewegung von doppelseitig eingespannten Balken untersucht; diese wurden mit konventioneller Mikrofabrikation aus verspanntem Silizium-Nitrid gefertigt. Die große Zugspannung in den Balken führt zu einer hohen mechanischen Stabilität und ebenso zu hohen mechanischen Güten.
Ein Teil der Arbeit befasste sich mit der Entwicklung neuer Detektions- und Antriebsmechanismen. Unter Ausnutzung der Polarisierbarkeit des Resonators wurde ein lokaler Antrieb realisiert, der sich durch besondere Einfachkeit auszeichnet. Ebenso wurden Fortschritte in der optischen Detektion erzielt. Ein Photodetektor konnte innerhalb einer optischen Wellenlänge Abstand zum Resonator plaziert werden; dies ermöglicht die lokale Detektion seiner Bewegung.
Hochempfindliche Messungen nutzen oft optische Resonanzen; bisherige Umsetzungen basieren auf Reflexionen und sind daher auf Objekte beschränkt, die größer als die verwendete Wellenlänge sind. In einer Zusammenarbeit mit Prof. Kippenberge konnte diese Beschränkung umgangen werden, indem geführtes Licht in einem Mikro-Toroiden verwendet wurde.
Weiter wurde in der Arbeit die resonante Bewegung selbst untersucht. Im Bereich hoher Amplituden zeigt die rĂĽcktreibende Kraft nichtlineares Verhalten. Das sich dadurch ergebende bistabile Verhalten des Resonators wurde mit Hilfe von kurzen, resonanten Pulsen untersucht; schnelles Schalten wurde erreicht.
Die mechanische Dämpfung der Siliziumnitrid Resonatoren wurde untersucht. Die hohen Güten von Systemen unter Zugspannung konnte erklärt werden durch die sich ergebende erhöhte gespeicherte elastische Energie; im Gegensatz zu einem veränderten Dämpfungsverhalten
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Sensing Distant Nuclear Spins with a Single Electron Spin
We experimentally demonstrate the use of a single electronic spin to measure the quantum dynamics of distant individual nuclear spins from within a surrounding spin bath. Our technique exploits coherent control of the electron spin, allowing us to isolate and monitor nuclear spins weakly coupled to the electron spin. Specifically, we detect the evolution of distant individual C13 nuclear spins coupled to single nitrogen vacancy centers in a diamond lattice with hyperfine couplings down to a factor of 8 below the electronic spin bare dephasing rate. Potential applications to nanoscale magnetic resonance imaging and quantum information processing are discussed.Physic
Nonlinear Switching Dynamics in a Nanomechanical Resonator
The oscillatory response of nonlinear systems exhibits characteristic
phenomena such as multistability, discontinuous jumps and hysteresis. These can
be utilized in applications leading, e.g., to precise frequency measurement,
mixing, memory elements, reduced noise characteristics in an oscillator or
signal amplification. Approaching the quantum regime, concepts have been
proposed that enable low backaction measurement techniques or facilitate the
visualisation of quantum mechanical effects. Here we study the dynamic response
of nanoelectromechanical resonators in the nonlinear regime aiming at a more
detailed understanding and an exploitation for switching applications. Whereas
most previous investigations concentrated on dynamic phenomena arising at the
onset of bistability, we present experiments that yield insight into the
non-adiabatic evolution of the system while subjected to strong driving pulses
and the subsequent relaxation. Modeling the behaviour quantitatively with a
Duffing oscillator, we can control switching between its two stable states at
high speeds, exceeding recently demonstrated results by 10,000
Sensing distant nuclear spins with a single electron spin
We experimentally demonstrate the use of a single electronic spin to measure
the quantum dynamics of distant individual nuclear spins from within a
surrounding spin bath. Our technique exploits coherent control of the electron
spin, allowing us to isolate and monitor nuclear spins weakly coupled to the
electron spin. Specifically, we detect the evolution of distant individual
carbon-13 nuclear spins coupled to single nitrogen vacancy centers in a diamond
lattice with hyperfine couplings down to a factor of 8 below the electronic
spin bare dephasing rate. Potential applications to nanoscale magnetic
resonance imaging and quantum information processing are discussed.Comment: Corrected typos, updated references. 5 pages, 4 figures, and
supplemental materia
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Efficient Readout of a Single Spin State in Diamond via Spin-to-Charge Conversion
Efficient readout of individual electronic spins associated with atomlike impurities in the solid state is essential for applications in quantum information processing and quantum metrology. We demonstrate a new method for efficient spin readout of nitrogen-vacancy (NV) centers in diamond. The method is based on conversion of the electronic spin state of the NV to a charge-state distribution, followed by single-shot readout of the charge state. Conversion is achieved through a spin-dependent photoionization process in diamond at room temperature. Using NVs in nanofabricated diamond beams, we demonstrate that the resulting spin readout noise is within a factor of 3 of the spin projection noise level. Applications of this technique for nanoscale magnetic sensing are discussed.Physic
Universal transduction scheme for nanomechanical systems based on dielectric forces
Any polarizable body placed in an inhomogeneous electric field experiences a dielectric force. This phenomenon is well known from the macroscopic world: a water jet is deflected when approached by a charged object. This fundamental mechanism is exploited in a variety of contexts—for example, trapping microscopic particles in an optical tweezer1, where the trapping force is controlled via the intensity of a laser beam, or dielectrophoresis2, where electric fields are used to manipulate particles in liquids. Here we extend the underlying concept to the rapidly evolving field of nanoelectromechanical systems3, 4 (NEMS). A broad range of possible applications are anticipated for these systems5, 6, 7, but drive and detection schemes for nanomechanical motion still need to be optimized8, 9. Our approach is based on the application of dielectric gradient forces for the controlled and local transduction of NEMS. Using a set of on-chip electrodes to create an electric field gradient, we polarize a dielectric resonator and subject it to an attractive force that can be modulated at high frequencies. This universal actuation scheme is efficient, broadband and scalable. It also separates the driving scheme from the driven mechanical element, allowing for arbitrary polarizable materials and thus potentially ultralow dissipation NEMS10. In addition, it enables simple voltage tuning of the mechanical resonance over a wide frequency range, because the dielectric force depends strongly on the resonator–electrode separation. We use the modulation of the resonance frequency to demonstrate parametric actuation11, 12. Moreover, we reverse the actuation principle to realize dielectric detection, thus allowing universal transduction of NEMS. We expect this combination to be useful both in the study of fundamental principles and in applications such as signal processing and sensing
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Coherent Sensing of a Mechanical Resonator with a Single-Spin Qubit
Mechanical systems can be influenced by a wide variety of small forces, ranging from gravitational to optical, electrical, and magnetic. When mechanical resonators are scaled down to nanometer-scale dimensions, these forces can be harnessed to enable coupling to individual quantum systems. We demonstrate that the coherent evolution of a single electronic spin associated with a nitrogen vacancy center in diamond can be coupled to the motion of a magnetized mechanical resonator. Coherent manipulation of the spin is used to sense driven and Brownian motion of the resonator under ambient conditions with a precision below 6 picometers. With future improvements, this technique could be used to detect mechanical zero-point fluctuations, realize strong spin-phonon coupling at a single quantum level, and implement quantum spin transducers.Physic