arXiv subjects

Lin Han

Publications and source records attributed to Lin Han.

30 records · Page 2Linked to original sources

arXiv2021

Radio-frequency C-V measurements with sub-attofarad sensitivity

We demonstrate the use of radio-frequency (rf) resonators to measure the capacitance of nano-scale semiconducting devices in field-effect transistor configurations. The rf resonator is attached to the gate or the lead of the device. Consequently, tuning the carrier density in the conducting channel of the device affects the resonance frequency, quantitatively reflecting its capacitance. We test the measurement method on InSb and InAs nanowires at dilution-refrigerator temperatures. The measured capacitances are consistent with those inferred from the periodicity of the Coulomb blockade of quantum dots realized in the same devices. In an implementation of the resonator using an off-chip superconducting spiral inductor we find sensitivity values reaching down to 75~zF/$\sqHz$ at 1~kHz measurement bandwidth, and noise down to 0.45~aF at 1~Hz bandwidth. We estimate the sensitivity of the method for a number of other implementations. In particular we predict typical sensitivity of about 40~zF/$\sqHz$ at room temperature with a resonator comprised of off-the-shelf components. Of several proposed applications, we demonstrate two: the capacitance measurement of several identical 80~nm-wide gates with a single resonator, and the field-effect mobility measurement of an individual nanowire with the gate capacitance measured in-situ.

cond-mat.mes-hall↗

arXiv2021

Rapid microwave-only characterization and readout of quantum dots using multiplexed gigahertz-frequency resonators

Superconducting resonators enable fast characterization and readout of mesoscopic quantum devices. Finding ways to perform measurements of interest on such devices using resonators only is therefore of great practical relevance. We report the experimental investigation of an InAs nanowire multi-quantum dot device by probing GHz resonators connected to the device. First, we demonstrate accurate extraction of the DC conductance from measurements of the high-frequency admittance. Because our technique does not rely on DC calibration, it could potentially obviate the need for DC measurements in semiconductor qubit devices. Second, we demonstrate multiplexed gate sensing and the detection of charge tunneling on microsecond time scales. The GHz detection of dispersive resonator shifts allows rapid acquisition of charge-stability diagrams, as well as resolving charge tunneling in the device with a signal-to-noise ratio of up to 15 in one microsecond. Our measurements show that GHz-frequency resonators may serve as a universal tool for fast tune-up and high-fidelity readout of semiconductor qubits.

cond-mat.mes-hall↗

arXiv2019

Revealing charge-tunneling processes between a quantum dot and a superconducting island through gate sensing

We report direct detection of charge-tunneling between a quantum dot and a superconducting island through radio-frequency gate sensing. We are able to resolve spin-dependent quasiparticle tunneling as well as two-particle tunneling involving Cooper pairs. The quantum dot can act as an RF-only sensor to characterize the superconductor addition spectrum, enabling us to access subgap states without transport. Our results provide guidance for future dispersive parity measurements of Majorana modes, which can be realized by detecting the parity-dependent tunneling between dots and islands.

cond-mat.mes-hall↗

arXiv2019

Multi-snapshot Newtonized Orthogonal Matching Pursuit for Line Spectrum Estimation with Multiple Measurement Vectors

In this paper, multi-snapshot Newtonized orthogonal matching pursuit (MNOMP) algorithm is proposed to deal with the line spectrum estimation with multiple measurement vectors (MMVs). MNOMP has the low computation complexity and state-of-the-art performance advantage of NOMP, and also includes two key steps: Detecting a new sinusoid on an oversampled discrete Fourier transform (DFT) grid and refining the parameters of already detected sinusoids to avoid the problem of basis mismatch. We provide a stopping criterion based on the overestimating probability of the model order. In addition, the convergence of the proposed algorithm is also proved. Finally, numerical results are conducted to show that the performance of MNOMP benefits from MMVs, and the effectiveness of MNOMP when compared against the state-of-the-art algorithms in terms of frequency estimation accuracy and computation complexity.

cs.IT↗

arXiv2018

Rigidity controls human desmoplastic matrix anisotropy to enable pancreatic cancer invasion via extracellular signal-regulated kinase 2

Only about 8 percent of patients with pancreatic ductal adenocarcinoma, PDAC, live up to 5 years following diagnosis; by 2020 PDAC will become the second most lethal cancer in the United States. PDAC includes an anisotropic fibrous-like stroma, desmoplasia, encompassing most of the tumor mass. Desmoplasia is produced by cancer-associated fibroblasts, CAFs, and their cell-derived extracellular matrices, CDMs. Since elimination of CAFs is detrimental to patients, CDM reprogramming, as opposed to desmoplasia ablation, is therapeutically desirable. In this study we used a human mimetic three-dimensional CAF producing CDM system and proceeded to study its dynamic architectural modifications, following underlying substrate stiffness alterations, using digital imaging analyses, atomic force microscopy, mathematical modeling, cell biology, biochemistry and human tissue quantitative simultaneous multiplex immunofluorescence. Results suggested that the architecture of CDMs can be manipulated to render a tumor-suppressive microenvironment. We posit that perhaps treatments that could reprogram desmoplasia to become tumor-restrictive or that could target tumoral ERK2 might provide future new means for treating PDAC patients.

q-bio.CB↗

arXiv2018

Binary Sparse Bayesian Learning Algorithm for One-bit Compressed Sensing

In this letter, a binary sparse Bayesian learning (BSBL) algorithm is proposed to slove the one-bit compressed sensing (CS) problem in both single measurement vector (SMV) and multiple measurement vectors (MMVs). By utilising the Bussgang-like decomposition, the one-bit CS problem can be approximated as a standard linear model. Consequently, the standard SBL algorithm can be naturally incorporated. Numerical results demonstrate the effectiveness of the BSBL algorithm.

cs.IT↗

arXiv2017

Charmless $B_{c} \to VV$ decays in the QCD factorization approach

In this paper, we studied the charmless $B_{c}\to VV$ ($V$ denotes the light ground $\rm SU(3)$ vector meson) decays within the framework of QCD factorization. In the evaluation, two different schemes for regulating the end-point divergence are adopted. One (scheme I) is to use parameterization model, which is usually employed in the QCD factorization approach; the other (scheme II) is based on the infrared finite gluon propagator of Cornwall prescription. It is found that, in the annihilation amplitudes, the end-point divergence appears only in the power-suppressed corrections related to the twist-3 distribution amplitudes of $V$-meson. The strength of annihilation amplitudes evaluated in scheme II is generally larger than the one in scheme I. Numerically, in the decay modes considered in this paper, the CKM-favored $B_{c} \to ρ^{-}ω, K^{*-}K^{*0} $ decays have the relatively large branching fractions, $\sim {\cal{O}}(10^{-7})$, and hence are likely to be the first observed by the future experiments. In addition, all of the decay modes are dominated by the longitudinal polarization state; numerically, $f_{L}(B_{c} \to VV) \gtrsim 99\%$.

hep-ph↗

arXiv2016

Study of Nonleptonic $B^{\ast}_{(s)}\to M_1 M_2$ $(M=D$, $D_s$, $π$, $K)$ Weak Decays with Factorization Approach

Motivated by the experiments of heavy flavor physics at running LHC and upgrading SuperKEKB/Belle-II in the future, the nonleptonic $B^{\ast}_{(s)}\to M_1 M_2$ $(M=D$, $D_s$, $π$, $K)$ weak decays are studied in this paper. The amplitudes are calculated with factorization approach, and the transition form factors $A_0^{B^{\ast}_{(s)}\to M_1}(0)$ are evaluated within BSW model. With the reasonable approximation $Γ_{tot}(B^*_{(s)})\simeq Γ(B^*_{(s)}\to B_{(s)}γ)$, our predictions of branching fractions are presented. Numerically, the CKM-favored tree-dominated $\bar{B}^{*0} \to D^+D^-_s$ and $\bar{B}^{*0}_s \to D^+_sD^-_s$ decays have the largest branching fractions of the order $\sim{\cal O}(10^{-8})$, and hence will be firstly observed by forthcoming Belle-II experiment. However, most of the other decay modes have the branching fractions~$<{\cal O}(10^{-9})$ and thus are hardly to be observed soon. Besides, for the possible detectable $B^{\ast}_{(s)}$ decays with branching fractions $\gtrsim{\cal O}(10^{-9})$, some useful ratios, such as $R_D$ {\it et al.,} are presented and discussed in detail.

hep-ph↗

arXiv2012

Revisiting the Annihilation Corrections in Non-leptonic $\bar{B}_s^0$ Decays within QCD Factorization

Motivated by the recent measurements of non-leptonic $\bar{B}_s^0$ decays by CDF and LHCb collaborations, especially the large ${\cal B}(\bar{B}_s^0\toπ^+π^-)$, we revisit the hard spectator and annihilation corrections in $\bar{B}_s^0$ decays within QCD factorization approach with two schemes for the possible parameters for the known end-point divergence appeared in the estimation of the hard spectator and annihilation diagrams. The first one is to conservatively estimate the possible contributions by parameterization (scheme I); another one uses an infrared finite gluon propagator (scheme II) to regulate the end-point singularity. In scheme I, with the constraints from the measured $\bar{B}_s^0\to PP (VV)$ decays, two (four) restricted solutions of the parameters spaces are found. In scheme II, we find that most of the theoretical predictions agree well with the experimental data with single parameter $m_{g}\sim 0.5{\rm GeV}$. However, within both schemes, ${\cal B}(\bar{B}_s^0\toϕϕ)$ are always much larger than ${\cal B}(\bar{B}_s^0\to K^{\ast 0}\bar{K}^{\ast 0})$ in contrast to the experimental results ${\cal B}(\bar{B}_s^0\toϕϕ)\simeq{\cal B}(\bar{B}_s^0\to K^{\ast 0}\bar{K}^{\ast 0})$. It is noted that the pattern ${\cal B}(\bar{B}_s^0\toϕϕ)>{\cal B}(\bar{B}_s^0\to K^{\ast 0}\bar{K}^{\ast 0})$ also persists in other theoretical framework, thus the present experimental result ${\cal B}(\bar{B}_s^0\toϕϕ) \simeq {\cal B}(\bar{B}_s^0\to K^{\ast 0}\bar{K}^{\ast 0})$ rises a challenge to theoretical approaches for B non-leptonic decays. Further refined measurements and theoretical studies are called for to resolve such a possible anomaly.

hep-ph↗

arXiv2011

Implications of the Anomalies in B_s^0-\bar{B}_s^0 Mixing for Anomalous Tensor Couplings

Motivated by the recently observed anomalous large dimuon charge asymmetry in neutral B decays and the unexpected large CP phase in the mixing-induced CP asymmetry for B_s-->J/ψϕdecay, we study the effects of the anomalous tensor couplings to pursue possible solution. With the constraints from the obsevables ϕ^{J/ψϕ}_s, a_{sl}^s and ΔM_s, the parameter spaces are severely restricted. Numerically, we find the anomalies in B_s^0-\bar{B}_s^0 mixing system could be moderated simultaneously by the contributions induced by the color-singlet or color-octet tensor operators with their respective nontrivial new weak phase ϕ_{T1}\approx28.0(15.6) degree or ϕ_{T8}\approx-62.1(-74.2) degree and relevant strength parameters g_{T1}\approx6.7(8.5)\times10^{-2} or g_{T8}\approx1.9(2.4)\times10^{-2} for the CP-violating phase ϕ^{J/ψϕ}_s=-0.77(+0.29,-0.37)(-2.36(+0.37,-0.29)), respectively.

hep-ph↗

arXiv2008

Concentration and Length Dependence of DNA Looping in Transcriptional Regulation

In many cases, transcriptional regulation involves the binding of transcription factors at sites on the DNA that are not immediately adjacent to the promoter of interest. This action at a distance is often mediated by the formation of DNA loops: Binding at two or more sites on the DNA results in the formation of a loop, which can bring the transcription factor into the immediate neighborhood of the relevant promoter. Though there have been a variety of insights into the combinatorial aspects of transcriptional control, the mechanism of DNA looping as an agent of combinatorial control in both prokaryotes and eukaryotes remains unclear. We use single-molecule techniques to dissect DNA looping in the lac operon. In particular, we measure the propensity for DNA looping by the Lac repressor as a function of the concentration of repressor protein and as a function of the distance between repressor binding sites. As with earlier single-molecule studies, we find (at least) two distinct looped states and demonstrate that the presence of these two states depends both upon the concentration of repressor protein and the distance between the two repressor binding sites. We find that loops form even at interoperator spacings considerably shorter than the DNA persistence length, without the intervention of any other proteins to prebend the DNA. The concentration measurements also permit us to use a simple statistical mechanical model of DNA loop formation to determine the free energy of DNA looping, or equivalently, the J-factor for looping.

q-bio.BM↗

arXiv2006

Biological Consequences of Tightly Bent DNA: The Other Life of a Macromolecular Celebrity

The mechanical properties of DNA play a critical role in many biological functions. For example, DNA packing in viruses involves confining the viral genome in a volume (the viral capsid) with dimensions that are comparable to the DNA persistence length. Similarly, eukaryotic DNA is packed in DNA-protein complexes (nucleosomes) in which DNA is tightly bent around protein spools. DNA is also tightly bent by many proteins that regulate transcription, resulting in a variation in gene expression that is amenable to quantitative analysis. In these cases, DNA loops are formed with lengths that are comparable to or smaller than the DNA persistence length. The aim of this review is to describe the physical forces associated with tightly bent DNA in all of these settings and to explore the biological consequences of such bending, as increasingly accessible by single-molecule techniques.

q-bio.BM↗