OmniVision Technologies (Germany)

Solid-state quantum systems that utilize optical and spin degrees of freedom in a spin–photon interface have found widespread application in emerging quantum technologies. Recently, molecular qubits have gained center stage as precisely tunable entities that present a compelling alternative to well-established, yet structurally less flexible point defects in solid-state systems. In this work, we disclose ground-state triplet (GST) carbenes embedded in a molecular matrix as organic qubits comprising two unpaired electrons in close proximity that can be optically initialed and read out. In-situ photoactivation enables the precise allo- cation of the carbene position and tuning of its density in the crystalline matrix and lays the ground for optically detected magnetic resonance (ODMR) with high fluorescence contrast of more than 40%, as well as record- high spin coherence times for a molecular spin–photon interface of T2 = 157(4) μs at a temperature of around 5 K. In addition, we show how state-of-the-art quantum chemical calcu- lations including multiscale geometry predictions and complete active space self-consistent field (CASSCF) computations offer comprehensive insight into fundamental spin characteristics. With that, for the first time a series of attractive properties could be united in a single solid-state qubit material: Exclusive usage of light elements (C,H,O,N), optical spin-selective excitations and relaxation pathways, and large zero-field splitting (ZFS) parameters on the order of a few GHz resulting in protection against decoherence sources at low magnetic fields. In this study, we take first steps into a hitherto dormant playground for the design and fabrication of molecular solid-state color centers made of purely organic compounds.

Abstract Nitrogen vacancy (NV) color centers in diamond have shown great potential for various applications in quantum technology due to their long coherence times, high sensitivity to magnetic fields and atomic scale resolution. However, one major challenge in utilizing near surface NV centers is the decoherence caused by spins and charges fluctuating on the surface, which affects the spin properties of the sensors. To reduce the induced noise, various oxygen surface treatments such as low power oxygen plasma treatment and annealing under oxygen atmosphere have been explored to terminate the diamond surface and reduce its impact on NV coherence. We showed that the NV center’s coherence time can be enhanced up to a factor of 3 over a large spectral range of noise. Double electron–electron resonance measurements revealed an extra source of decoherence, scaling similarly as the P1 spin bath. The improvement in coherence times is accompanied with an increase in measured ketone/ether content and reduction of sp 2 signal in x-ray photoelectron spectroscopy measurements. Finally we compared the performance of different NV ensembles and surface treatments for sensing external proton spins. The oxygen annealing is an effective procedure of enhancing the spin coherence times and reducing broad band spin noise experienced by shallow implanted ensemble NV centers in diamond.

Hyperpolarization techniques significantly enhance the sensitivity of magnetic resonance (MR) and thus present fascinating new directions for research and applications with in vivo MR imaging and spectroscopy (MRI/S). Hyperpolarized 13C MRI/S, in particular, enables real-time non-invasive assessment of metabolic processes and holds great promise for a diverse range of clinical applications spanning fields like oncology, neurology, and cardiology, with a potential for improving early diagnosis of disease, patient stratification, and therapy response assessment. Despite its potential, technical challenges remain for achieving clinical translation. This paper provides an overview of the discussions that took place at the international workshop “New Horizons in Hyperpolarized 13C MRI,” in March 2023 at the Bavarian Academy of Sciences and Humanities, Munich, Germany. The workshop covered new developments, as well as future directions, in topics including polarization techniques (particularly focusing on parahydrogen-based methods), novel probes, considerations related to data acquisition and analysis, and emerging clinical applications in oncology and other fields.

Solid-state magnetometers based on color centers in diamond are emerging as one of the leading quantum sensors due to their outstanding room-temperature properties, such as high sensitivity and calibration-free long-term stability. However, their integration into compact systems is still an active area of research. To tackle this challenge, in this paper, we present a quantum magnetometer based on negatively charged nitrogen-vacancy (NV) centers using a custom-designed, chip-integrated 4-way transmitter. In combination with a custom-designed microcoil array, the 4-way transmitter delivers microwave magnetic fields up to 226 µT for carrier frequencies around 7 GHz with a conversion gain of ≥32 dB to NV centers. The local oscillator (LO) signal required to drive the on-chip quadrature upconversion mixer is generated by a custom-designed quadrature PLL, which provides a 22% tuning range between 6.4 and 8 GHz, and a low phase noise of -122 dBc/Hz at 1 MHz offset from a 7 GHz carrier, to enable broadband, low-noise magnetometry. To verify the excellent performance of the integrated electronics, we have embedded them into a widefield diamond magnetometer using off-chip scanning optics, achieving a state-of-the-art AC-magnetic field limit of detection of 300 pT/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> .

There is a fundamental issue with the use of dynamic nuclear polarization (DNP) to enhance nuclear spin polarization: the same polarizing agent (PA) needed for DNP is also responsible for shortening the lifetime of the hyperpolarization. As a result, long-term storage and transport of hyperpolarized samples is severely restricted and the apparatus for DNP is necessarily located near or integrated with the apparatus using the hyperpolarized spins. In this paper, we demonstrate that naphthalene single crystals can serve as a long-lived reservoir of proton polarization that can be exploited to enhance signals in benchtop and high-field NMR of target molecules in solution at a site 300 km away by a factor of several thousand. The naphthalene protons are polarized using short-lived optically excited triplet states of pentacene instead of stable radicals. In the absence of optical excitation, the electron spins remain in a singlet ground state, eliminating the major pathway of nuclear spin-lattice relaxation. The polarization decays with a time constant of about 50 h at 80 K and 0.5 T or above 800 h at 5 K and 20 mT. A module based on a Halbach array yielding a field of 0.75 T and a conventional cryogenic dry shipper, operating at liquid nitrogen temperature, allows storage and long distance transport of the polarization to a remote laboratory, where the polarization of the crystal is transferred after dissolution to a target molecule of choice by intermolecular cross-relaxation. The procedure has been executed repeatedly and has proven to be reliable and robust.

RANdom SAmple Consensus (RANSAC) is widely used in computer vision and automotive related applications. It is an iterative method to estimate parameters of mathematical model from a set of observed data that contains outliers. In computer vision, such observed data is usually a set of features (such as feature points, line segments) extracted from images. In automotive related applications, RANSAC can be used to estimate lane vanishing point, camera rotation angles, ground plane etc. In such applications, changing content of road scene makes stable online model estimation very difficult. In this paper, we propose a framework called tRANSAC to dynamically accumulate features across time so that online RANSAC model estimation can be stably performed. Feature accumulation across time is done in such a dynamic way that when RANSAC tends to perform robustly and stably, accumulated features are discarded fast so that fewer redundant features are used for RANSAC estimation; when RANSAC tends to perform poorly, accumulated features are discarded slowly so that more features can be used for better RANSAC estimation. Experiment results on road scene dataset for camera angle estimation show that the proposed method gives more stable and accurate model compared to baseline method in online RANSAC estimation.

Hyperpolarization of nuclear spins enhances nuclear magnetic resonance signals, which play a key role for imaging and spectroscopy in the natural and life sciences. This signal amplification unlocks previously inaccessible techniques, such as metabolic imaging of cancer cells. In this paper, electron spins from the photoexcited triplet state of pentacene-doped naphthalene crystals are used to polarize surrounding protons. As existing strategies are rendered less effective by experimental constraints, they are replaced with optimal control pulses designed with redcrab. In contrast to previous optimal control approaches, which consider one or two effective nuclei, this closed-loop optimization is macroscopic. A 26% improvement in signal and 15% faster polarization rate are observed. Additionally, a strategy called autonomously optimized repeated linear sweep (ARISE) is introduced to efficiently tailor existing hyperpolarization sequences in the presence of experimental uncertainty to enhance their performance. ARISE is expected to be broadly applicable in many experimental settings.

It is known that poly(arylethersulfone)-based dialyzers can elute poly( N -vinyl-2-pyrrolidone) (PVP). With regard to chronic renal replacement therapy, this is a burden for the patient, because PVP is deposited in different organs and cannot be degraded or released from there; so elutable PVP has to be minimized. Usually, the iodine method is used for quantification of extractable PVP. To overcome the chain length dependency of this method, we used an ultraviolet method that is independent from the PVP chain lengths; so the absolute amount of eluted PVP can be quantified. The current study shows the amount of eluted PVP on differently sterilized low flux dialyzers (1.6 m 2 , similar storage time, n = 12)-PS160 (Allmed, Egypt), F7HPS (Fresenius Medical Care, Germany), F16 (Wego, China), and B-16P (Bain, China). Using the ultraviolet method, the irradiated filters show a sum total of approximately 9 mg more eluted PVP compared with the steam-sterilized ones, whereas the iodine method shows a value about three times lower between different types of sterilization. The boundary conditions during the radiation sterilization could lead to PVP degradation instead of cross-linking. The resulting shorter PVP chains can be more easily rinsed out and can falsely decrease the calculated eluted PVP amount by using the iodine complexation method.

This paper reviews and discusses the design of a low-power single-full-band (3.1–10.6 GHz) noncarrier impulse-radio ultra wideband (UWB) transmitter featuring 5th-order Gaussian derivative pulse shaping, integrated BPSK modulation, and 2.5 kV whole-chip ESD (electrostatic discharge) protection. The UWB transmitter design has been implemented in a commercial 0.18 μm CMOS technology with a very small die size of 0.25 mm2. The fabricated chips have demonstrated full functionality, extremely low power consumption of 0.14 pJ/p-mV, and an ultra short pulse width of 394 ps. This ESD-protected UWB transmitter has the potential to support wireless streaming to gigabit per second (Gbps).