arXiv subjects

Min Li

Publications and source records attributed to Min Li.

304 records · Page 17Linked to original sources

arXiv2012

Multiple Access Channels with States Causally Known at Transmitters

It has been recently shown by Lapidoth and Steinberg that strictly causal state information can be beneficial in multiple access channels (MACs). Specifically, it was proved that the capacity region of a two-user MAC with independent states, each known strictly causally to one encoder, can be enlarged by letting the encoders send compressed past state information to the decoder. In this work, a generalization of the said strategy is proposed whereby the encoders compress also the past transmitted codewords along with the past state sequences. The proposed scheme uses a combination of long-message encoding, compression of the past state sequences and codewords without binning, and joint decoding over all transmission blocks. The proposed strategy has been recently shown by Lapidoth and Steinberg to strictly improve upon the original one. Capacity results are then derived for a class of channels that include two-user modulo-additive state-dependent MACs. Moreover, the proposed scheme is extended to state-dependent MACs with an arbitrary number of users. Finally, output feedback is introduced and an example is provided to illustrate the interplay between feedback and availability of strictly causal state information in enlarging the capacity region.

cs.IT↗

arXiv2012

Quantum random walk in periodic potential on a line

We investigated the discrete-time quantum random walks on a line in periodic potential. The probability distribution with periodic potential is more complex compared to the normal quantum walks, and the standard deviation $σ$ has interesting behaviors for different period $q$ and parameter $θ$. We studied the behavior of standard deviation with variation in walk steps, period, and $θ$. The standard deviation increases approximately linearly with $θ$ and decreases with $1/q$ for $θ\in(0,π/4)$, and increases approximately linearly with $1/q$ for $θ\in[π/4,π/2)$. When $q=2$, the standard deviation is lazy for $θ\in[π/4+nπ,3π/4+nπ],n\in Z$.

quant-ph↗

arXiv2012

Average position in quantum walks with a U(2) coin

We investigated discrete-time quantum walks with an arbitary unitary coin. Here we discover that the average position $ =\max( \sin(α+γ)$, while the initial state is $1/\sqrt{2}(\mid0L>+i\mid0R>)$. We prove the result and get some symmetry properties of quantum walks with a U(2) coin with $\mid0L>$ and $\mid0R>$ as the initial state.

quant-ph↗

arXiv2012

Nonperturbative tuning of an improved relativistic heavy-quark action with application to bottom spectroscopy

We calculate the masses of bottom mesons using an improved relativistic action for the b-quarks and the RBC/UKQCD Iwasaki gauge configurations with 2+1 flavors of dynamical domain-wall light quarks. We analyze configurations with two lattice spacings: a^{-1} = 1.729 GeV (a ~ 0.11 fm) and a^{-1} = 2.281 GeV (a ~ 0.086 fm). We use an anisotropic, clover-improved Wilson action for the b-quark, and tune the three parameters of the action nonperturbatively such that they reproduce the experimental values of the B_s and B_s* heavy-light meson states. The masses and mass-splittings of the low-lying bottomonium states (such as the eta_b and Upsilon) can then be computed with no additional inputs, and comparison between these predictions and experiment provides a test of the validity of our method. We obtain bottomonium masses with total uncertainties of ~0.5-0.6% and fine-structure splittings with uncertainties of ~35-45%; for all cases we find good agreement with experiment. The parameters of the relativistic heavy-quark action tuned for b-quarks presented in this work can be used for precise calculations of weak matrix elements such as B-meson decay constants and mixing parameters with lattice discretization errors that are of the same size as in light pseudoscalar meson quantities. This general method can also be used for charmed meson masses and matrix elements if the parameters of the heavy-quark action are appropriately tuned.

hep-lat↗

arXiv2012

Degraded Broadcast Diamond Channels with Non-Causal State Information at the Source

A state-dependent degraded broadcast diamond channel is studied where the source-to-relays cut is modeled with two noiseless, finite-capacity digital links with a degraded broadcasting structure, while the relays-to-destination cut is a general multiple access channel controlled by a random state. It is assumed that the source has non-causal channel state information and the relays have no state information. Under this model, first, the capacity is characterized for the case where the destination has state information, i.e., has access to the state sequence. It is demonstrated that in this case, a joint message and state transmission scheme via binning is optimal. Next, the case where the destination does not have state information, i.e., the case with state information at the source only, is considered. For this scenario, lower and upper bounds on the capacity are derived for the general discrete memoryless model. Achievable rates are then computed for the case in which the relays-to-destination cut is affected by an additive Gaussian state. Numerical results are provided that illuminate the performance advantages that can be accrued by leveraging non-causal state information at the source.

cs.IT↗

arXiv2011

Message and State Cooperation in a Relay Channel When the Relay Has Strictly Causal State Information

A state-dependent relay channel is studied in which strictly causal channel state information is available at the relay and no state information is available at the source and destination. Source and relay are connected via two unidirectional out-of-band orthogonal links of finite capacity, and a state-dependent memoryless channel connects source and relay, on one side, and the destination, on the other. Via the orthogonal links, the source can convey information about the message to be delivered to the destination to the relay while the relay can forward state information to the source. This exchange enables cooperation between source and relay on both transmission of message and state information to the destination. First, an achievable scheme, inspired by noisy network coding, is proposed that exploits both message and state cooperation. Next, based on the given achievable rate and appropriate upper bounds, capacity results are identified for some special cases. Finally, a Gaussian model is studied, along with corresponding numerical results that illuminate the relative merits of state and message cooperation.

cs.IT↗

arXiv2010

THz generation by dual-color pulse in prealigned molecules

We demonstrate that the THz generation in air from a dual-color pulse, composed of the fundamental and second-harmonic waves, can be coherently controlled by field-free molecular alignment. By tuning its time delay to properly match various molecular alignment revivals, the THz generation from the dual-color pulse can be promoted or decreased due to the spatial cross-(de)focusing effect and the alignment-dependent ionization probabilities of the prealigned diatomic molecules of air. For the dual-color pulse of orthogonally polarized fundamental and second-harmonic waves, the polarization of the generated THz radiation can be controlled by the field-free molecular alignment, which functions as a transient dynamic wave-plate for the dual-color pulse with different phase velocities for the orthogonally polarized field components. The plasma effect on the THz generation of the dual-color pulse is also observed, leading to additional intensity and polarization control of the THz radiation.

physics.optics↗

arXiv2010

A central limit theorem under sublinear expectations

In this paper we consider a sequence of random variables with mean uncertainty in a sublinear expectation space. Without the hypothesis of identical distributions, we show a new central limit theorem under the sublinear expectations.

math.PR↗

arXiv2009

The finite temperature QCD using 2+1 flavors of domain wall fermions at N_t = 8

We study the region of the QCD phase transition using 2+1 flavors of domain wall fermions (DWF) and a $16^3 \times 8$ lattice volume with a fifth dimension of $L_s = 32$. The disconnected light quark chiral susceptibility, quark number susceptibility and the Polyakov loop suggest a chiral and deconfining crossover transition lying between 155 and 185 MeV for our choice of quark mass and lattice spacing. In this region the lattice scale deduced from the Sommer parameter $r_0$ is $a^{-1} \approx 1.3$ GeV, the pion mass is $\approx 300$ MeV and the kaon mass is approximately physical. The peak in the chiral susceptibility implies a pseudo critical temperature $T_c = 171(10)(17)$ MeV where the first error is associated with determining the peak location and the second with our unphysical light quark mass and non-zero lattice spacing. The effects of residual chiral symmetry breaking on the chiral condensate and disconnected chiral susceptibility are studied using several values of the valence $L_s$.

hep-lat↗

arXiv2009

Quantitative Determination of Spatial Protein-protein Proximity in Fluorescence Confocal Microscopy

To quantify spatial protein-protein proximity (colocalization) in fluorescence microscopic images, cross-correlation and autocorrelation functions were decomposed into fast and slowly decaying components. The fast component results from clusters of proteins specifically labeled and the slow one from background/image heterogeneity. We show that the calculation of the protein-protein proximity index and the correlation coefficient are more reliably determined by extracting the fast-decaying component.

physics.bio-ph↗

arXiv2008

Bottom spectroscopy on dynamical 2+1 flavor domain wall fermion lattices with a relativistic heavy quark action

Following the successful application of the relativistic heavy quark(RHQ) action to the charmonium and charm-strange meson spectrum, we study here the bottom system to explore the validity of this method in a regime with larger heavy quark momenta. The spectrum is calculated using the same dynamical 2+1 flavor, $24^3\times 64$ domain wall fermion lattice configurations generated by the RBC and UKQCD collaborations and used in the earlier charm study. The 3 parameters in the RHQ action are determined by matching to the experimental bottom-strange meson masses and extrapolated to the chiral limit from three different sea quark masses. We predict the bottomonium mass spectrum and compare it with experiment. A theoretical estimation is also carried out to understand the $O(a^2p^2)$ systematic errors found in the numerical study.

hep-lat↗

arXiv2007

Q-DPM: An Efficient Model-Free Dynamic Power Management Technique

When applying Dynamic Power Management (DPM) technique to pervasively deployed embedded systems, the technique needs to be very efficient so that it is feasible to implement the technique on low end processor and tight-budget memory. Furthermore, it should have the capability to track time varying behavior rapidly because the time varying is an inherent characteristic of real world system. Existing methods, which are usually model-based, may not satisfy the aforementioned requirements. In this paper, we propose a model-free DPM technique based on Q-Learning. Q-DPM is much more efficient because it removes the overhead of parameter estimator and mode-switch controller. Furthermore, its policy optimization is performed via consecutive online trialing, which also leads to very rapid response to time varying behavior.

cs.OH↗

arXiv2007

Charm spectroscopy on dynamical 2+1 flavor domain wall fermion lattices with a relativistic heavy quark action

We present a preliminary calculation of the charmonium spectrum using the dynamical 2+1 flavor $24^3\times 64$ domain wall fermion lattice configurations generated by the RBC and UKQCD collaborations. We use the relativistic heavy quark action with 3 parameters non-perturbatively determined by matching to experimental quantities. Chiral extrapolation is done on four light sea quark masses from 0.005 to 0.03, with $m_s=0.04$ and $m_{res}=0.003$. We can either predict meson masses assuming the lattice spacing is known from other methods, or calculate the lattice spacing using those quantities.

hep-lat↗

arXiv2006

The static quark potential for dynamical domain wall fermion simulations

We present preliminary results for the static quark potential computed on some of the DWF lattice configurations generated by the RBC-UKQCD collaborations. Most of these results were obtained using Wilson lines joining spatial planes fixed into the Coulomb gauge. We compare the results from this method with the earlier ones on $16^3 \times 32$ lattices using Bresenham spatial paths with APE smeared link variables. Some preliminary results on $24^3 \times 64$ lattices are also presented.

hep-lat↗

arXiv2006

Relativistic Heavy Quark Effective Action

We study the fermion action needed to accurately describe the low energy physics of systems including heavy quarks in lattice QCD even when the heavy fermion mass $m$ is on the order of, or larger than, the inverse lattice spacing: $m \ge 1/a$. We carry out an expansion through first order in $|\vec p| a$ (where $\vec p$ is the heavy quark momentum) and all orders in $ma$, refining the analysis of the Fermilab and Tsukuba groups. We demonstrate that the spectrum of heavy quark bound states can be determined accurately through $|\vec p| a$ and $(ma)^n$ for arbitrary exponent $n$ by using a lattice action containing only three unknown coefficients: $m_0$, $ζ$ and $c_P$ (a generalization of $c_{SW}$), which are functions of $ma$. In a companion paper, we show how these three coefficients can be precisely determined using non-perturbative techniques.

hep-lat↗

arXiv2004

Scalable XSLT Evaluation

XSLT is an increasingly popular language for processing XML data. It is widely supported by application platform software. However, little optimization effort has been made inside the current XSLT processing engines. Evaluating a very simple XSLT program on a large XML document with a simple schema may result in extensive usage of memory. In this paper, we present a novel notion of \emph{Streaming Processing Model} (\emph{SPM}) to evaluate a subset of XSLT programs on XML documents, especially large ones. With SPM, an XSLT processor can transform an XML source document to other formats without extra memory buffers required. Therefore, our approach can not only tackle large source documents, but also produce large results. We demonstrate with a performance study the advantages of the SPM approach. Experimental results clearly confirm that SPM improves XSLT evaluation typically 2 to 10 times better than the existing approaches. Moreover, the SPM approach also features high scalability.

cs.DB↗