22 research outputs found
Coherent manipulation of nuclear spins in the strong driving regime
Spin-based quantum information processing makes extensive use of spin-state
manipulation. This ranges from dynamical decoupling of nuclear spins in quantum
sensing experiments to applying logical gates on qubits in a quantum processor.
Here we present an antenna for strong driving in quantum sensing experiments
and theoretically address challenges of the strong driving regime. First, we
designed and implemented a micron-scale planar spiral RF antenna capable of
delivering intense fields to a sample. The planar antenna is tailored for
quantum sensing experiments using the diamond's nitrogen-vacancy (NV) center
and should be applicable to other solid-state defects. The antenna has a broad
bandwidth of 22 MHz, is compatible with scanning probes, and is suitable for
cryogenic and ultrahigh vacuum conditions. We measure the magnetic field
induced by the antenna and estimate a field-to-current ratio of
G/A, representing a x6 increase in efficiency compared to the state-of-the-art.
We demonstrate the antenna by driving Rabi oscillations in H spins of an
organic sample on the diamond surface and measure H Rabi frequencies of
over 500 kHz, i.e., -pulses shorter than 1 - faster than
previously reported in NV-based nuclear magnetic resonance (NMR). Finally, we
discuss the implications of driving spins with a field tilted from the
transverse plane in a regime where the driving amplitude is comparable to the
spin-state splitting, such that the rotating wave approximation does not
describe the dynamics well. We present a recipe to optimize pulse fidelity in
this regime based on a phase and offset-shifted sine drive, that may be
optimized without numerical optimization procedures or precise modeling of the
experiment. We consider this approach in a range of driving amplitudes and show
that it is particularly efficient in the case of a tilted driving field
Coherent manipulation of nuclear spins in the strong driving regime
Spin-based quantum information processing makes extensive use of spin-state manipulation. This ranges from dynamical decoupling of nuclear spins in quantum sensing experiments to applying logical gates on qubits in a quantum processor. Fast manipulation of spin states is highly desirable for accelerating experiments, enhancing sensitivity, and applying elaborate pulse sequences. Strong driving using intense radio-frequency (RF) fields can, therefore, facilitate fast manipulation and enable broadband excitation of spin species. In this work, we present an antenna for strong driving in quantum sensing experiments and theoretically address challenges of the strong driving regime. First, we designed and implemented a micron-scale planar spiral RF antenna capable of delivering intense fields to a sample. The planar antenna is tailored for quantum sensing experiments using the diamond's nitrogen-vacancy (NV) center and should be applicable to other solid-state defects. The antenna has a broad bandwidth of 22 MHz, is compatible with scanning probes, and is suitable for cryogenic and ultrahigh vacuum conditions. We measure the magnetic field induced by the antenna and estimate a field-to-current ratio of 113 +/- 16 G/A, representing a six-fold increase in efficiency compared to the state-of-the-art, crucial for cryogenic experiments. We demonstrate the antenna by driving Rabi oscillations in 1H spins of an organic sample on the diamond surface and measure 1H Rabi frequencies of over 500 kHz, i.e. pi -pulses shorter than 1 mu s -an order of magnitude faster than previously reported in NV-based nuclear magnetic resonance (NMR). Finally, we discuss the implications of driving spins with a field tilted from the transverse plane in a regime where the driving amplitude is comparable to the spin-state splitting, such that the rotating wave approximation does not describe the dynamics well. We present a simple recipe to optimize pulse fidelity in this regime based on a phase and offset-shifted sine drive, which may be optimized in situ without numerical optimization procedures or precise modeling of the experiment. We consider this approach in a range of driving amplitudes and show that it is particularly efficient in the case of a tilted driving field. The results presented here constitute a foundation for implementing fast nuclear spin control in various systems
Towards Quantum Sensing of Chiral-Induced Spin Selectivity: Probing Donor-Bridge-Acceptor Molecules with NV Centers in Diamond
Photoexcitable donor-bridge-acceptor (D-B-A) molecules that support
intramolecular charge transfer are ideal platforms to probe the influence of
chiral-induced spin selectivity (CISS) in electron transfer and resulting
radical pairs. In particular, the extent to which CISS influences spin
polarization or spin coherence in the initial state of spin-correlated radical
pairs following charge transfer through a chiral bridge remains an open
question. Here, we introduce a quantum sensing scheme to measure directly the
hypothesized spin polarization in radical pairs using shallow nitrogen-vacancy
(NV) centers in diamond at the single- to few-molecule level. Importantly, we
highlight the perturbative nature of the electron spin-spin dipolar coupling
within the radical pair, and demonstrate how Lee-Goldburg decoupling can
preserve spin polarization in D-B-A molecules for enantioselective detection by
a single NV center. The proposed measurements will provide fresh insight into
spin selectivity in electron transfer reactions.Comment: 7 pages and 4 pages appendix including an extensive description of
the initial spin state of photo-generated radical pair
Single Nitrogen-Vacancy-NMR of Amine-Functionalized Diamond Surfaces
Nuclear magnetic resonance (NMR) imaging with shallow nitrogen-vacancy (NV)
centers in diamond offers an exciting route toward sensitive and localized
chemical characterization at the nanoscale. Remarkable progress has been made
to combat the degradation in coherence time and stability suffered by
near-surface NV centers using suitable chemical surface termination. However,
approaches that also enable robust control over adsorbed molecule density,
orientation, and binding configuration are needed. We demonstrate a diamond
surface preparation for mixed nitrogen- and oxygen-termination that
simultaneously improves NV center coherence times for emitters <10-nm-deep and
enables direct and recyclable chemical functionalization via amine-reactive
crosslinking. Using this approach, we probe single NV centers embedded in
nanopillar waveguides to perform NMR sensing of covalently
bound trifluoromethyl tags in the ca. 50-100 molecule regime. This work
signifies an important step toward nuclear spin localization and structure
interrogation at the single-molecule level.Comment: 21 pages and 16 pages supporting informatio
Multicone Diamond Waveguides for Nanoscale Quantum Sensing
The long-lived electronic spin of the nitrogen-vacancy (NV) center in diamond
is a promising quantum sensor for detecting nanoscopic magnetic and electric
fields in a variety of experimental conditions. Nevertheless, an outstanding
challenge in improving measurement sensitivity is the poor signal-to-noise
ratio (SNR) of prevalent optical spin-readout techniques. Here, we address this
limitation by coupling individual NV centers to optimized diamond nanopillar
structures, thereby improving optical collection efficiency of fluorescence.
First, we optimize the structure in simulation, observing an increase in
collection efficiency for tall ( 5 m) pillars with tapered
sidewalls. We subsequently verify these predictions by fabricating and
characterizing a representative set of structures using a reliable and
reproducible nanofabrication process. An optimized device yields increased SNR,
owing to improvements in collimation and directionality of emission.
Promisingly, these devices are compatible with low-numerical-aperture,
long-working-distance collection optics, as well as reduced tip radius,
facilitating improved spatial resolution for scanning applications.Comment: 22 pages, five figure
Diamond surface engineering for molecular sensing with nitrogen-vacancy centers
Quantum sensing using optically addressable atomic-scale defects, such as the
nitrogen--vacancy (NV) center in diamond, provides new opportunities for
sensitive and highly localized characterization of chemical functionality.
Notably, near-surface defects facilitate detection of the minute magnetic
fields generated by nuclear or electron spins outside of the diamond crystal,
such as those in chemisorbed and physisorbed molecules. However, the promise of
NV centers is hindered by a severe degradation of critical sensor properties,
namely charge stability and spin coherence, near surfaces (< ca. 10 nm deep).
Moreover, applications in the chemical sciences require methods for covalent
bonding of target molecules to diamond with robust control over density,
orientation, and binding configuration. This forward-looking Review provides a
survey of the rapidly converging fields of diamond surface science and
NV-center physics, highlighting their combined potential for quantum sensing of
molecules. We outline the diamond surface properties that are advantageous for
NV-sensing applications, and discuss strategies to mitigate deleterious effects
while simultaneously providing avenues for chemical attachment. Finally, we
present an outlook on emerging applications in which the unprecedented
sensitivity and spatial resolution of NV-based sensing could provide unique
insight into chemically functionalized surfaces at the single-molecule level.Comment: Review paper, 36 page
Parallel time integration using Batched BLAS (Basic Linear Algebra Subprograms) routines
We present an approach for integrating the time evolution of quantum systems. We leverage the computation power of graphics processing units (GPUs) to perform the integration of all time steps in parallel. The performance boost is especially prominent for small to medium-sized quantum systems. The devised algorithm can largely be implemented using the recently-specified batched versions of the BLAS routines, and can therefore be easily ported to a variety of platforms. Our PARAllelized Matrix Exponentiation for Numerical Time evolution (PARAMENT) implementation runs on CUDA-enabled graphics processing units.
Program summary
Program Title: PARAMENT
CPC Library link to program files: https://doi.org/10.17632/zy5v4xs89d.1
Developer's repository link: https://github.com/parament-integrator/parament
Licensing provisions: Apache 2.0
Programming language: C / CUDA / Python
Nature of problem: Time-integration of the Schrödinger equation with a time-dependent Hamiltonian for quantum systems with a small Hilbert space but many time-steps.
Solution method: A 4th order Magnus integrator, highly parallelized on a GPU, implemented using a small subset of BLAS functions for improved portability.ISSN:0010-4655ISSN:1879-294
Deployment of cooperative ITS in Germany (C-ITS Corridor)
Die Initiative der Einführung kooperativer Systeme in einem Korridor von Rotterdam über Frankfurt/Main nach Wien, dem sogenannten C-ITS Corridor, und damit auch in Deutschland wurde im Juni 2013 durch die Unterzeichnung einer entsprechenden Absichtserklärung des Bundesministeriums für Verkehr, Bau und Stadtentwicklung mit den Verkehrsministern der Niederlande und Österreichs offiziell gestartet. In vielen Forschungsprojekten wurden vorher die Grundlagen erarbeitet, um eine solche Einführung technisch überhaupt erst möglich zu machen. Im Beitrag werden diese Ergebnisse nochmals kurz aufgegriffen und um den aktuellen Stand bei den Entwicklungen im C-ITS Corridor erweitert. Als erstes Einführungsszenario wurden die Baustellenwarnung und Kooperatives Verkehrsmanagement unter Einbeziehung von Fahrzeugdaten gewählt. Nicht verschwiegen werden sollen hierbei auch die wesentlichen Herausforderungen, die im Übergang von Forschung und Feldtests zu realen Anwendungen liegen.The initiative for the deployment of cooperative ITS in a corridor from Rotterdam via Frankfurt/M. to Vienna; the so called C-ITS Corridor, and by association in Germany, officially started in June 2013 with the signing of the corresponding memorandum of understanding by the BMVBS and the ministers of transport from the Netherlands and Austria. Many research projects did work hard for the fundamentals to technically enable the deployment at all. In the following these results are shortly taken up once more and will be expanded by the current status of the developments in the C-ITS Corridor. As a first deployment scenario Road Works Warning and Cooperative Traffic Management based on vehicle data were selected. Not kept secret shall be the major challenges which lie within the transition from research and field operational tests to real implementation
Double resonance calibration of g factor standards: Carbon fibers as a high precision standard
The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than gfree with g=2.002644=gfree·(1+162ppm) with a relative uncertainty of 15ppm. This precisely known g factor and their inertness qualify them as a high precision g factor standard for general purposes. The double resonance experiment for calibration is applicable to other potential standards with a hyperfine interaction averaged by a process with very short correlation time.ISSN:1090-780
Tracking the precession of single nuclear spins by weak measurements
ISSN:0028-0836ISSN:1476-468