Publications and Awards
05. February 2021
Membrane-Based Scanning Force Microscopy
David Hälg*, Thomas Gisler*, Yeghishe Tsaturyan, Letizia Catalini, Urs Grob, Marc-Dominik Krass, Martin Héritier, Hinrich Mattiat, Ann-Katrin Thamm, Romana Schirhagl, Eric C. Langman, Albert Schliesser, Christian L. Degen, and Alexander Eichler * These authors contributed equally to this work.
We report the development of a scanning force microscope based on an ultrasensitive silicon nitride membrane optomechanical transducer. Our development is made possible by inverting the standard microscope geometry—in our instrument, the substrate is vibrating and the scanning tip is at rest. We present topography images of samples placed on the membrane surface. Our measurements demonstrate that the membrane retains an excellent force sensitivity when loaded with samples and in the presence of a scanning tip. We discuss the prospects and limitations of our instrument as a quantum-limited force sensor and imaging tool.
21. July 2020
Travel Award
David Hälg
David Hälg was awarded one out of 3 travel grants (CHF 1500) by Zurich Instruments for his work on "Membrane-based scanning-force microscopy". Congrats David!
21. July 2020
Spin Detection via Parametric Frequency Conversion in a Membrane Resonator
Jan Košata, Oded Zilberberg, Christian L. Degen, R. Chitra, and Alexander Eichler
Recent demonstrations of ultracoherent nanomechanical resonators introduce the prospect of developing protocols for solid-state sensing applications. Here, we propose to use two coupled ultracoherent resonator modes on a Si3N4 membrane for the detection of small nuclear spin ensembles. To this end, we employ parametric frequency conversion between nondegenerate modes. The nondegenerate modes result from coupled degenerate resonators, and the parametric conversion is mediated by periodic inversions of the nuclear spins in the presence of a magnetic scanning tip. We analyze potential noise sources and derive the achievable signal-to-noise ratio with typical experimental parameter values. Our proposal reconciles the geometric constraints of optomechanical systems with the requirements of scanning force microscopy and brings forth a promising platform for spin-phonon interaction and spin imaging.
21. July 2020
Soft-Clamped Phononic Dimers for Mechanical Sensing and Transduction
Letizia Catalini, Yeghishe Tsaturyan, and Albert Schliesser
Coupled micro and nanomechanical resonators are of significant interest within a number of areas of research, ranging from synchronization, nonlinear dynamics and chaos, to quantum sensing and transduction. Building upon our work on soft-clamped membrane resonators, here we present a study on phononic dimers, consisting of two defects embedded in a phononic crystal membrane. These devices exhibit widely tunable (2–100 kHz) interdefect coupling strengths, leading to delocalized hybrid modes with mechanical Q*f products >10^14 Hz at room temperature, ensuring low thermomechanical force noise. The mode splitting exhibits a strong dependence on the dimer orientation within the crystal lattice, as well as the spatial separation between the two defects. Given the importance of dynamic range for sensing applications, we characterize the relevant mechanical nonlinearities, specifically the self- and cross-Duffing parameters, as well as self- and cross-nonlinear dampings. This work establishes soft-clamped resonators with engineered spatial and spectral multimode structure as a versatile mechanical platform both in the classical and quantum regimes. Applications in microwave-to-optical transduction and magnetic resonance force microscopy are particularly attractive prospects.
20. February 2020
Magnetic resonance force microscopy with a one-dimensional resolution of 0.9 nanometers
U. Grob, M. D. Krass, M. Héritier, R. Pachlatko, J. Rhensius, J. Kosata, B. A. Moores, H. Takahashi, A. Eichler, and C. L. Degen
Magnetic resonance force microscopy (MRFM) is a scanning probe technique capable of detecting MRI signals fromnanoscale sample volumes, providing a paradigm-changing potential for structural biology and medical research. Thus far, however, experiments have not reached sufficient spatial resolution for retrieving meaningful structural information from samples. In this work, we report MRFM imaging scans demonstrating a resolution of 0.9 nm and a localization precision of 0.6 nm in one dimension. Our progress is enabled by an improved spin excitation protocol furnishing us with sharp spatial control on the MRFM imaging slice, combined with overall advances in instrument stability. From a modeling of the slice function, we expect that our arrangement supports spatial resolutions down to 0.3 nm given sufficient signal-to-noise ratio. Our experiment demonstrates the feasibility of subnanometer MRI and realizes an important milestone toward the three-dimensional imaging of macromolecular structures.
19. December 2019
Rapid Flipping of Parametric Phase States
Martin Frimmer, Toni L. Heugel, Žiga Nosan, Felix Tebbenjohanns, David Hälg, Abdulkadir Akin, Christian L. Degen, Lukas Novotny, R. Chitra, Oded Zilberberg, and Alexander Eichler
We experimentally demonstrate flipping the phase state of a parametron within a single period of its oscillation. A parametron is a binary logic element based on a driven nonlinear resonator. It features two stable phase states that define an artificial spin. The most basic operation performed on a parametron is a bit flip between these two states. Thus far, this operation involved changing the energetic population of the resonator and therefore required a number of oscillations on the order of the quality factor Q. Our technique takes a radically different approach and relies on rapid control of the underlying potential. Our work represents a paradigm shift for phase-encoded logic operations by boosting the speed of a parametron bit flip to its ultimate limit.
23. October 2019
Quantum Transducer Using a Parametric Driven-Dissipative Phase Transition
Toni L. Heugel, Matteo Biondi, Oded Zilberberg, and R. Chitra
We study a dissipative Kerr resonator subject to both single- and two-photon detuned drives. Beyond a critical detuning threshold, the Kerr resonator exhibits a semiclassical first-order dissipative phase transition between two different steady states that are characterized by a π phase switch of the cavity field. This transition is shown to persist deep into the quantum limit of low photon numbers. Remarkably, the detuning frequency at which this transition occurs depends almost linearly on the amplitude of the single-photon drive. Based on this phase-switching feature, we devise a sensitive quantum transducer that translates the observed frequency of the parametric quantum phase transition to the detected single-photon amplitude signal. The effects of noise and temperature on the corresponding sensing protocol are addressed, and a realistic circuit-QED implementation is discussed.
19. September 2019
Classical Many-Body Time Crystals
Toni L. Heugel, Matthias Oscity, Alexander Eichler, Oded Zilberberg, and R. Chitra
Discrete time crystals are a many-body state of matter where the extensive system’s dynamics are slower than the forces acting on it. Nowadays, there is a growing debate regarding the specific properties required to demonstrate such a many-body state, alongside several experimental realizations. In this work, we provide a simple and pedagogical framework by which to obtain many-body time crystals using parametrically coupled resonators. In our analysis, we use classical period-doubling bifurcation theory and present a clear distinction between single-mode time-translation symmetry breaking and a situation where an extensive number of degrees of freedom undergo the transition. We experimentally demonstrate this paradigm using coupled mechanical oscillators, thus providing a clear route for time crystal realizations in real materials.
02. July 2019
Gate-controlled phase switching in a parametron
Ž. Nosan, P. Märki, N. Hauff, C. Knaut, and A. Eichler
The parametron, a resonator-based logic device, is a promising physical platform for emerging computational paradigms. When the parametron is subject to both parametric pumping and external driving, complex phenomena arise that can be harvested for applications. In this paper, we experimentally demonstrate deterministic phase switching of a parametron by applying frequency tuning pulses. To our surprise, we find different regimes of phase switching due to the interplay between a parametric pump and an external drive. We provide full modeling of our device with numerical simulations and find excellent agreement between model and measurements. Our result opens up new possibilities for fast and robust logic operations within large-scale parametron architectures.
07. June 2018
Swiss Nanoconvention Poster Award 2018
D. Hälg, T. Gisler, H. Mattiat, U. Grob, M.-D. Krass, M. Héritier, A. Eichler, C. Degen, Y. Tsaturyan, A. Schliesser
David Hälg received the Swiss Nanoconvention Poster Award 2018 for his poster 'Development of a membrane-based AFM'.
06. June 2018
A parametric symmetry breaking transducer
Alexander Eichler, Toni L. Heugel, Anina Leuch, Christian L. Degen, R. Chitra, and Oded Zilberberg
Force detectors rely on resonators to transduce forces into a readable signal. Usually, these resonators operate in the linear regime and their signal appears amidst a competing background comprising thermal or quantum fluctuations as well as readout noise. Here, we demonstrate a parametric symmetry breaking transduction method that leads to a robust nonlinear force detection in the presence of noise. The force signal is encoded in the frequency at which the system jumps between two phase states which are inherently protected against phase noise. Consequently, the transduction effectively decouples from readout noise channels. For a controlled demonstration of the method, we experiment with a macroscopic doubly clamped string. Our method provides a promising paradigm for high-precision force detection.