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Publications in Physics & Astronomy by NOMIS researchers

Mesoscale properties of protein clusters determine the size and nature of liquid-liquid phase separation (LLPS)

NOMIS Researcher(s)

Published in

June 2, 2025

The observation of Liquid-Liquid Phase Separation (LLPS) in biological cells has dramatically shifted the paradigm that soluble proteins are uniformly dispersed in the cytoplasm or nucleoplasm. The LLPS region is preceded by a one-phase solution, where recent experiments have identified clusters in an aqueous solution with 102-103 proteins. Here, we theoretically consider a core-shell model with mesoscale core, surface, and bending properties of the clusters’ shell and contrast two experimental paradigms for the measured cluster size distributions of the Cytoplasmic Polyadenylation Element Binding-4 (CPEB4) and Fused in Sarcoma (FUS) proteins. The fits to the theoretical model and earlier electron paramagnetic resonance (EPR) experiments suggest that the same protein may exhibit hydrophilic, hydrophobic, and amphiphilic conformations, which act to stabilize the clusters. We find that CPEB4 clusters are much more stable compared to FUS clusters, which are less energetically favorable. This suggests that in CPEB4, LLPS consists of large-scale aggregates of clusters, while for FUS, clusters coalesce to form micron-scale LLPS domains.

Research field(s)
Biological Physics, Chemical Physics

DOI
10.1038/s42005-025-02134-w

Large closed-basin lakes sustainably supplied phosphate during the origins of life

NOMIS Researcher(s)

Published in

February 19, 2025

The origin of life on Earth required a supply of phosphorus (P) for the synthesis of universal biomolecules. Closed lakes may have accumulated high P concentrations on early Earth. However, it is not clear whether prebiotic P uptake in such settings would then have been sustainable. We show that large closed-basin lakes can combine high P concentrations at steady state with extremely high rates of biological productivity. Our case study is Mono Lake in California, which has close to 1 millimolar dissolved P at steady state despite extremely high rates of biological productivity, in contrast to smaller closed basins where life is scarce. Hence, large closed-basin lakes offer an environment where high rates of prebiotic P productivity can plausibly coexist with high steady-state P concentrations. Such lakes should have readily formed on the heavily cratered and volcanically active surface of early Earth.

Partnership(s)
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Research field(s)
Physics & Astronomy

DOI
10.1126/sciadv.adq0027

Cosmic dust fertilization of glacial prebiotic chemistry on early Earth

NOMIS Researcher(s)

Published in

February 19, 2024

Earth’s surface is deficient in available forms of many elements considered limiting for prebiotic chemistry. In contrast, many extraterrestrial rocky objects are rich in these same elements. Limiting prebiotic ingredients may, therefore, have been delivered by exogenous material; however, the mechanisms by which exogeneous material may be reliably and non-destructively supplied to a planetary surface remains unclear. Today, the flux of extraterrestrial matter to Earth is dominated by fine-grained cosmic dust. Although this material is rarely discussed in a prebiotic context due to its delivery over a large surface area, concentrated cosmic dust deposits are known to form on Earth today due to the action of sedimentary processes. Here we combine empirical constraints on dust sedimentation with dynamical simulations of dust formation and planetary accretion to show that localized sedimentary deposits of cosmic dust could have accumulated in arid environments on early Earth, in particular glacial settings that today produce cryoconite sediments. Our results challenge the widely held assumption that cosmic dust is incapable of fertilizing prebiotic chemistry. Cosmic dust deposits may have plausibly formed on early Earth and acted to fertilize prebiotic chemistry.

Research field(s)
Earth & Environmental Sciences, Physics & Astronomy

DOI
10.1038/s41550-024-02212-z

Leaf metabolic traits reveal hidden dimensions of plant form and function

NOMIS Researcher(s)

Published in

August 30, 2023

The metabolome is the biochemical basis of plant form and function, but we know little about its macroecological variation across the plant kingdom. Here, we used the plant functional trait concept to interpret leaf metabolome variation among 457 tropical and 339 temperate plant species. Distilling metabolite chemistry into five metabolic functional traits reveals that plants vary on two major axes of leaf metabolic specialization—a leaf chemical defense spectrum and an expression of leaf longevity. Axes are similar for tropical and temperate species, with many trait combinations being viable. However, metabolic traits vary orthogonally to life-history strategies described by widely used functional traits. The metabolome thus expands the functional trait concept by providing additional axes of metabolic specialization for examining plant form and function. Copyright © 2023 The Authors,

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1126/sciadv.adi4029

Inductively shunted transmons exhibit noise insensitive plasmon states and a fluxon decay exceeding 3 hours

NOMIS Researcher(s)

Published in

July 5, 2023

Currently available quantum processors are dominated by noise, which severely limits their applicability and motivates the search for new physical qubit encodings. In this work, we introduce the inductively shunted transmon, a weakly flux-tunable superconducting qubit that offers charge offset protection for all levels and a 20-fold reduction in flux dispersion compared to the state-of-the-art resulting in a constant coherence over a full flux quantum. The parabolic confinement provided by the inductive shunt as well as the linearity of the geometric superinductor facilitates a high-power readout that resolves quantum jumps with a fidelity and QND-ness of >90% and without the need for a Josephson parametric amplifier. Moreover, the device reveals quantum tunneling physics between the two prepared fluxon ground states with a measured average decay time of up to 3.5 h. In the future, fast time-domain control of the transition matrix elements could offer a new path forward to also achieve full qubit control in the decay-protected fluxon basis. © 2023, The Author(s).

Research field(s)
Natural Sciences, Physics & Astronomy, General Physics

DOI
10.1038/s41467-023-39656-2

X-ray Thomson scattering spectra from density functional theory molecular dynamics simulations based on a modified Chihara formula

NOMIS Researcher(s)

Published in

June 14, 2023

We study ab initio approaches for calculating x-ray Thomson scattering spectra from density functional theory molecular dynamics simulations based on a modified Chihara formula that expresses the inelastic contribution in terms of the dielectric function. We study the electronic dynamic structure factor computed from the Mermin dielectric function using an ab initio electron-ion collision frequency in comparison to computations using a linear-response time-dependent density functional theory (LR-TDDFT) framework for hydrogen and beryllium and investigate the dispersion of free-free and bound-free contributions to the scattering signal. A separate treatment of these contributions, where only the free-free part follows the Mermin dispersion, shows good agreement with LR-TDDFT results for ambient-density beryllium, but breaks down for highly compressed matter where the bound states become pressure ionized. LR-TDDFT is used to reanalyze x-ray Thomson scattering experiments on beryllium demonstrating strong deviations from the plasma conditions inferred with traditional analytic models at small scattering angles. © 2023 American Physical Society.

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1103/PhysRevE.107.065207

Melting curve of superionic ammonia at planetary interior conditions

NOMIS Researcher(s)

Published in

May 29, 2023

Under high pressures and temperatures, molecular systems with substantial polarization charges, such as ammonia and water, are predicted to form superionic phases and dense fluid states with dissociating molecules and high electrical conductivity. This behaviour potentially plays a role in explaining the origin of the multipolar magnetic fields of Uranus and Neptune, whose mantles are thought to result from a mixture of H2O, NH3 and CH4 ices. Determining the stability domain, melting curve and electrical conductivity of these superionic phases is therefore crucial for modelling planetary interiors and dynamos. Here we report the melting curve of superionic ammonia up to 300 GPa from laser-driven shock compression of pre-compressed samples and atomistic calculations. We show that ammonia melts at lower temperatures than water above 100 GPa and that fluid ammonia’s electrical conductivity exceeds that of water at conditions predicted by hot, super-adiabatic models for Uranus and Neptune, and enhances the conductivity in their fluid water-rich dynamo layers. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1038/s41567-023-02074-8

Tunable directional photon scattering from a pair of superconducting qubits

NOMIS Researcher(s)

Published in

May 24, 2023

The ability to control the direction of scattered light is crucial to provide flexibility and scalability for a wide range of on-chip applications, such as integrated photonics, quantum information processing, and nonlinear optics. Tunable directionality can be achieved by applying external magnetic fields that modify optical selection rules, by using nonlinear effects, or interactions with vibrations. However, these approaches are less suitable to control microwave photon propagation inside integrated superconducting quantum devices. Here, we demonstrate on-demand tunable directional scattering based on two periodically modulated transmon qubits coupled to a transmission line at a fixed distance. By changing the relative phase between the modulation tones, we realize unidirectional forward or backward photon scattering. Such an in-situ switchable mirror represents a versatile tool for intra- and inter-chip microwave photonic processors. In the future, a lattice of qubits can be used to realize topological circuits that exhibit strong nonreciprocity or chirality. © 2023, The Author(s).

Research field(s)
Natural Sciences, Physics & Astronomy, Optics

DOI
h10.1038/s41467-023-38761-6

Curvature induces active velocity waves in rotating spherical tissues

NOMIS Researcher(s)

Published in

March 24, 2023

The multicellular organization of diverse systems, including embryos, intestines, and tumors relies on coordinated cell migration in curved environments. In these settings, cells establish supracellular patterns of motion, including collective rotation and invasion. While such collective modes have been studied extensively in flat systems, the consequences of geometrical and topological constraints on collective migration in curved systems are largely unknown. Here, we discover a collective mode of cell migration in rotating spherical tissues manifesting as a propagating single-wavelength velocity wave. This wave is accompanied by an apparently incompressible supracellular flow pattern featuring topological defects as dictated by the spherical topology. Using a minimal active particle model, we reveal that this collective mode arises from the effect of curvature on the active flocking behavior of a cell layer confined to a spherical surface. Our results thus identify curvature-induced velocity waves as a mode of collective cell migration, impacting the dynamical organization of 3D curved tissues. © 2023, The Author(s).

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1038/s41467-023-37054-2

Thermodynamics of diamond formation from hydrocarbon mixtures in planets

NOMIS Researcher(s)

Published in

February 27, 2023

Hydrocarbon mixtures are extremely abundant in the Universe, and diamond formation from them can play a crucial role in shaping the interior structure and evolution of planets. With first-principles accuracy, we first estimate the melting line of diamond, and then reveal the nature of chemical bonding in hydrocarbons at extreme conditions. We finally establish the pressure-temperature phase boundary where it is thermodynamically possible for diamond to form from hydrocarbon mixtures with different atomic fractions of carbon. Notably, here we show a depletion zone at pressures above 200 GPa and temperatures below 3000 K-3500 K where diamond formation is thermodynamically favorable regardless of the carbon atomic fraction, due to a phase separation mechanism. The cooler condition of the interior of Neptune compared to Uranus means that the former is much more likely to contain the depletion zone. Our findings can help explain the dichotomy of the two ice giants manifested by the low luminosity of Uranus, and lead to a better understanding of (exo-)planetary formation and evolution. © 2023, The Author(s).

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1038/s41467-023-36841-1

Majorana-like Coulomb spectroscopy in the absence of zero-bias peaks

NOMIS Researcher(s)

Published in

December 15, 2022

Hybrid semiconductor–superconductor devices hold great promise for realizing topological quantum computing with Majorana zero modes1–5. However, multiple claims of Majorana detection, based on either tunnelling6–10 or Coulomb blockade (CB) spectroscopy11,12, remain disputed. Here we devise an experimental protocol that allows us to perform both types of measurement on the same hybrid island by adjusting its charging energy via tunable junctions to the normal leads. This method reduces ambiguities of Majorana detections by checking the consistency between CB spectroscopy and zero-bias peaks in non-blockaded transport. Specifically, we observe junction-dependent, even–odd modulated, single-electron CB peaks in InAs/Al hybrid nanowires without concomitant low-bias peaks in tunnelling spectroscopy. We provide a theoretical interpretation of the experimental observations in terms of low-energy, longitudinally confined island states rather than overlapping Majorana modes. Our results highlight the importance of combined measurements on the same device for the identification of topological Majorana zero modes.

Research field(s)
Natural Sciences, Physics & Astronomy, Applied Physics

DOI
10.1038/s41586-022-05382-w

Downstream Effects of Mutations in SOD1 and TARDBP Converge on Gene Expression Impairment in Patient-Derived Motor Neurons

NOMIS Researcher(s)

Published in

September 1, 2022

Amyotrophic Lateral Sclerosis (ALS) is a progressive and fatal neurodegenerative disease marked by death of motor neurons (MNs) present in the spinal cord, brain stem and motor cortex. Despite extensive research, the reason for neurodegeneration is still not understood. To generate novel hypotheses of putative underlying molecular mechanisms, we used human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs) from SOD1- and TARDBP (TDP-43 protein)-mutant-ALS patients and healthy controls to perform high-throughput RNA-sequencing (RNA-Seq). An integrated bioinformatics approach was employed to identify differentially expressed genes (DEGs) and key pathways underlying these familial forms of the disease (fALS). In TDP43-ALS, we found dysregulation of transcripts encoding components of the transcriptional machinery and transcripts involved in splicing regulation were particularly affected. In contrast, less is known about the role of SOD1 in RNA metabolism in motor neurons. Here, we found that many transcripts relevant for mitochondrial function were specifically altered in SOD1-ALS, indicating that transcriptional signatures and expression patterns can vary significantly depending on the causal gene that is mutated. Surprisingly, however, we identified a clear downregulation of genes involved in protein translation in SOD1-ALS suggesting that ALS-causing SOD1 mutations shift cellular RNA abundance profiles to cause neural dysfunction. Altogether, we provided here an extensive profiling of mRNA expression in two ALS models at the cellular level, corroborating the major role of RNA metabolism and gene expression as a common pathomechanism in ALS.

Research field(s)
Natural Sciences, Physics & Astronomy, Chemical Physics

DOI
10.3390/ijms23179652

Effects of boundary layer thickness on the estimation of equivalent sandgrain roughness in zero-pressure-gradient boundary layers

NOMIS Researcher(s)

Published in

August 1, 2022

Experiments were conducted in zero-pressure-gradient boundary layers over a rough surface. Profiles of mean velocity and turbulence quantities were acquired using laser Doppler velocimetry at twelve streamwise locations for each of three different freestream velocities. Momentum thickness Reynolds numbers ranged from 1550 to 13,650. The roughness was stochastic with positive skewness, and the ratio of the boundary layer thickness, δ, to the root-mean-square roughness height varied from 55 to 141. The equivalent sandgrain roughness height, ks, was approximately 4 times the rms roughness height. In the outer region of the boundary layer, the mean velocity and turbulence results were found to be invariant with Reynolds number and δ, when scaled using δ and the friction velocity. The outer region quantities exhibited similarity with equivalent smooth-wall boundary layer quantities, in agreement with results from the literature. The equivalent sandgrain roughness was computed from the mean velocity results using a standard correlation, and was found to vary noticeably and inversely with δ when δ/ks was less than about 40. The possible existence of a modified correlation to account for the δ/ks dependence was discussed. Such a correlation might prove useful for extracting ks values from low δ/ks data and for predicting the effect of roughness with a known ks on boundary layers with varying δ/ks. Graphical abstract: [Figure not available: see fulltext.]

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1007/s00348-022-03479-6

Phase-separating RNA-binding proteins form heterogeneous distributions of clusters in subsaturated solutions

NOMIS Researcher(s)

Published in

July 12, 2022

Macromolecular phase separation is thought to be one of the processes that drives the formation of membraneless biomolecular condensates in cells. The dynamics of phase separation are thought to follow the tenets of classical nucleation theory, and, therefore, subsaturated solutions should be devoid of clusters with more than a few molecules. We tested this prediction using in vitro biophysical studies to characterize subsaturated solutions of phase-separating RNA-binding proteins with intrinsically disordered prion-like domains and RNA-binding domains. Surprisingly, and in direct contradiction to expectations from classical nucleation theory, we find that subsaturated solutions are characterized by the presence of heterogeneous distributions of clusters. The distributions of cluster sizes, which are dominated by small species, shift continuously toward larger sizes as protein concentrations increase and approach the saturation concentration. As a result, many of the clusters encompass tens to hundreds of molecules, while less than 1% of the solutions are mesoscale species that are several hundred nanometers in diameter. We find that cluster formation in subsaturated solutions and phase separation in supersaturated solutions are strongly coupled via sequence-encoded interactions. We also find that cluster formation and phase separation can be decoupled using solutes as well as specific sets of mutations. Our findings, which are concordant with predictions for associative polymers, implicate an interplay between networks of sequence-specific and solubility-determining interactions that, respectively, govern cluster formation in subsaturated solutions and the saturation concentrations above which phase separation occurs.

Research field(s)
Natural Sciences, Physics & Astronomy, Chemical Physics

DOI
10.1073/pnas.2202222119

Geometry Adaptation of Protrusion and Polarity Dynamics in Confined Cell Migration

NOMIS Researcher(s)

Published in

July 1, 2022

Cell migration in confining physiological environments relies on the concerted dynamics of several cellular components, including protrusions, adhesions with the environment, and the cell nucleus. However, it remains poorly understood how the dynamic interplay of these components and the cell polarity determine the emergent migration behavior at the cellular scale. Here, we combine data-driven inference with a mechanistic bottom-up approach to develop a model for protrusion and polarity dynamics in confined cell migration, revealing how the cellular dynamics adapt to confining geometries. Specifically, we use experimental data of joint protrusion-nucleus migration trajectories of cells on confining micropatterns to systematically determine a mechanistic model linking the stochastic dynamics of cell polarity, protrusions, and nucleus. This model indicates that the cellular dynamics adapt to confining constrictions through a switch in the polarity dynamics from a negative to a positive self-reinforcing feedback loop. Our model further reveals how this feedback loop leads to stereotypical cycles of protrusion-nucleus dynamics that drive the migration of the cell through constrictions. These cycles are disrupted upon perturbation of cytoskeletal components, indicating that the positive feedback is controlled by cellular migration mechanisms. Our data-driven theoretical approach therefore identifies polarity feedback adaptation as a key mechanism in confined cell migration.

Research field(s)
Natural Sciences, Physics & Astronomy, General Physics

DOI
10.1103/PhysRevX.12.031041

Sequence-dependent surface condensation of a pioneer transcription factor on DNA

NOMIS Researcher(s)

Published in

March 1, 2022

Biomolecular condensates are dense assemblies of proteins that form distinct biochemical compartments without being surrounded by a membrane. Some, such as P granules and stress granules, behave as droplets and contain many millions of molecules. Others, such as transcriptional condensates that form on the surface of DNA, are small and contain thousands of molecules. The physics behind the formation of small condensates on DNA surfaces is still under discussion. Here we investigate the nature of transcription factor condensates using the pioneer transcription factor Krüppel-like factor 4 (Klf4). We show that Klf4 can phase separate on its own at high concentrations, but at low concentrations, Klf4 only forms condensates on DNA. Using optical tweezers, we demonstrate that these Klf4 condensates form on DNA as a type of surface condensation. This surface condensation involves a switch-like transition from a thin adsorbed layer to a thick condensed layer, which shows hallmarks of a prewetting transition. The localization of condensates on DNA correlates with sequence, suggesting that the condensate formation of Klf4 on DNA is a sequence-dependent form of surface condensation. Prewetting together with sequence specificity can explain the size and position control of surface condensates. We speculate that a prewetting transition of pioneer transcription factors on DNA underlies the formation and positioning of transcriptional condensates and provides robustness to transcriptional regulation.

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1038/s41567-021-01462-2

Nanomaterials as Ultrasound Theragnostic Tools for Heart Disease Treatment/Diagnosis

NOMIS Researcher(s)

Published in

February 1, 2022

A variety of different nanomaterials (NMs) such as microbubbles (MBs), nanobubbles (NBs), nanodroplets (NDs), and silica hollow meso-structures have been tested as ultrasound contrast agents for the detection of heart diseases. The inner part of these NMs is made gaseous to yield an ultrasound contrast, which arises from the difference in acoustic impedance between the interior and exterior of such a structure. Furthermore, to specifically achieve a contrast in the diseased heart region (DHR), NMs can be designed to target this region in essentially three different ways (i.e., passively when NMs are small enough to diffuse through the holes of the vessels supplying the DHR, actively by being associated with a ligand that recognizes a receptor of the DHR, or magnetically by applying a magnetic field orientated in the direction of the DHR on a NM responding to such stimulus). The localization and resolution of ultrasound imaging can be further improved by applying ultrasounds in the DHR, by increasing the ultrasound frequency, or by using harmonic, sub-harmonic, or super-resolution imaging. Local imaging can be achieved with other non-gaseous NMs of metallic composition (i.e., essentially made of Au) by using photoacoustic imaging, thus widening the range of NMs usable for cardiac applications. These contrast agents may also have a therapeutic efficacy by carrying/activating/releasing a heart disease drug, by triggering ultrasound targeted microbubble destruction or enhanced cavitation in the DHR, for example, resulting in thrombolysis or helping to prevent heart transplant rejection.

Research field(s)
Natural Sciences, Physics & Astronomy, Chemical Physics

DOI
10.3390/ijms23031683

Interleukin‐17 and th17 lymphocytes directly impair motoneuron survival of wildtype and fus‐als mutant human ipscs

NOMIS Researcher(s)

Published in

August 1, 2021

Amyotrophic lateral sclerosis (ALS) is a progressive disease leading to the degeneration of motor neurons (MNs). Neuroinflammation is involved in the pathogenesis of ALS; however, interactions of specific immune cell types and MNs are not well studied. We recently found a shift toward T helper (Th)1/Th17 cell‐mediated, pro‐inflammatory immune responses in the peripheral immune system of ALS patients, which positively correlated with disease severity and progression. Whether Th17 cells or their central mediator, Interleukin‐17 (IL‐17), directly affects human motor neuron survival is currently unknown. Here, we evaluated the contribution of Th17 cells and IL‐17 on MN degeneration using the co‐culture of iPSC‐derived MNs of fused in sarcoma (FUS)‐ALS patients and isogenic controls with Th17 lymphocytes derived from ALS patients, healthy controls, and multiple sclerosis (MS) patients (positive control). Only Th17 cells from MS patients induced severe MN degeneration in FUS‐ALS as well as in wildtype MNs. Their main effector, IL‐17A, yielded in a dose‐dependent decline of the viability and neurite length of MNs. Surprisingly, IL‐17F did not influence MNs. Importantly, neutralizing IL‐17A and anti‐IL‐17 receptor A treatment re-verted all effects of IL‐17A. Our results offer compelling evidence that Th17 cells and IL‐17A do directly contribute to MN degeneration.

Research field(s)
Natural Sciences, Physics & Astronomy, Chemical Physics

DOI
10.3390/ijms22158042

The als-associated fus (P525l) variant does not directly interfere with microtubule-dependent kinesin-1 motility

NOMIS Researcher(s)

Published in

March 1, 2021

Deficient intracellular transport is a common pathological hallmark of many neuro-degenerative diseases, including amyotrophic lateral sclerosis (ALS). Mutations in the fused-in-sarcoma (FUS) gene are one of the most common genetic causes for familial ALS. Motor neurons carrying a mutation in the nuclear localization sequence of FUS (P525L) show impaired axonal transport of several organelles, suggesting that mislocalized cytoplasmic FUS might directly interfere with the transport machinery. To test this hypothesis, we studied the effect of FUS on kinesin-1 motility in vitro. Using a modified microtubule gliding motility assay on surfaces coated with kinesin-1 motor proteins, we showed that neither recombinant wildtype and P525L FUS variants nor lysates from isogenic ALS-patient-specific iPSC-derived spinal motor neurons expressing those FUS variants significantly affected gliding velocities. We hence conclude that during ALS pathogenesis the initial negative effect of FUS (P525L) on axonal transport is an indirect nature and requires additional factors or mechanisms.

Research field(s)
Natural Sciences, Physics & Astronomy, Chemical Physics

DOI
10.3390/ijms22052422

Converting microwave and telecom photons with a silicon photonic nanomechanical interface

NOMIS Researcher(s)

Published in

December 1, 2020

Practical quantum networks require low-loss and noise-resilient optical interconnects as well as non-Gaussian resources for entanglement distillation and distributed quantum computation. The latter could be provided by superconducting circuits but existing solutions to interface the microwave and optical domains lack either scalability or efficiency, and in most cases the conversion noise is not known. In this work we utilize the unique opportunities of silicon photonics, cavity optomechanics and superconducting circuits to demonstrate a fully integrated, coherent transducer interfacing the microwave X and the telecom S bands with a total (internal) bidirectional transduction efficiency of 1.2% (135%) at millikelvin temperatures. The coupling relies solely on the radiation pressure interaction mediated by the femtometer-scale motion of two silicon nanobeams reaching a Vπ as low as 16 μV for sub-nanowatt pump powers. Without the associated optomechanical gain, we achieve a total (internal) pure conversion efficiency of up to 0.019% (1.6%), relevant for future noise-free operation on this qubit-compatible platform.

Research field(s)
Natural Sciences, Physics & Astronomy, Optics

DOI
10.1038/s41467-020-18269-z

Surpassing the Resistance Quantum with a Geometric Superinductor

NOMIS Researcher(s)

Published in

October 29, 2020

Superinductors have a characteristic impedance exceeding the resistance quantum RQ≈6.45kω, which leads to a suppression of ground-state charge fluctuations. Applications include the realization of hardware-protected qubits for fault-tolerant quantum computing, improved coupling to small-dipole-moment objects, and the definition of a new quantum-metrology standard for the ampere. In this work, we refute the widespread notion that superinductors can only be implemented based on kinetic inductance, i.e., using disordered superconductors or Josephson-junction arrays. We present the modeling, fabrication, and characterization of 104 planar aluminum-coil resonators with a characteristic impedance up to 30.9 kω at 5.6 GHz and a capacitance down to ≤1 fF, with low loss and a power handling reaching 108 intracavity photons. Geometric superinductors are free of uncontrolled tunneling events and offer high reproducibility, linearity, and the ability to couple magnetically – properties that significantly broaden the scope of future quantum circuits.

Research field(s)
Natural Sciences, Physics & Astronomy, Applied Physics

DOI
10.1103/PhysRevApplied.14.044055

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