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For an interconnection network $G$, the {\it $\omega$-wide diameter} $d_\omega(G)$ is the least $\ell$ such that any two vertices are joined by $\omega$ internally-disjoint paths of length at most $\ell$, and the {\it $(\omega-1)$-fault…

Discrete Mathematics · Computer Science 2016-06-21 Meijie Ma , Douglas B. West , Jun-Ming Xu

Multi-spectral frequency combs provide frontier architectures for laser standoff spectroscopy, optical clockwork, and high-capacity optical communications. Frequency microcombs, aided by their high-quality resonances and inherent…

Let $p$ and $q$ be two distinct fixed prime numbers and $(n_i)_{i\geq 0}$ the sequence of consecutive integers of the form $p^a\cdot q^b$ with $a,b\ge 0$. Tijdeman gave a lower bound (1973) and an upper bound (1974) for the gap size…

Number Theory · Mathematics 2025-11-27 Alessandro Languasco , Florian Luca , Pieter Moree , Alain Togbé

Optical frequency combs, named for their comb-like peaks in the spectrum, are essential for various sensing applications. As the technology develops, its performance has reached the standard quantum limit dictated by the quantum…

Quantum Physics · Physics 2026-05-25 Haowei Shi , Quntao Zhuang

This paper introduces a new variant of hypercubes, which we call Z-cubes. The n-dimensional Z-cube $H_n$ is obtained from two copies of the (n-1)-dimensional Z-cube $H_{n-1}$ by adding a special perfect matching between the vertices of…

Combinatorics · Mathematics 2015-09-24 Xuding Zhu

A code $C \colon \{0,1\}^k \to \{0,1\}^n$ is a $q$-locally decodable code ($q$-LDC) if one can recover any chosen bit $b_i$ of the message $b \in \{0,1\}^k$ with good confidence by randomly querying the encoding $x := C(b)$ on at most $q$…

Computational Complexity · Computer Science 2023-08-30 Omar Alrabiah , Venkatesan Guruswami , Pravesh K. Kothari , Peter Manohar

A subset of the Hamming cube over $n$-letter alphabet is said to be $d$-maximal if its diameter is $d$, and adding any point increases the diameter. Our main result shows that each $d$-maximal set is either of size at most $(n+o(n))^d$ or…

Combinatorics · Mathematics 2025-07-16 Boris Bukh , Aleksandre Saatashvili

A frequency rectangle of type FR$(m,n;q)$ is an $m \times n$ matrix such that each symbol from a set of size $q$ appears $n/q$ times in each row and $m/q$ times in each column. Two frequency rectangles of the same type are said to be…

Combinatorics · Mathematics 2022-12-22 Fahim Rahim , Nicholas J. Cavenagh

The $n$-dimensional hypercube $Q_n$ is a graph with vertex set $\{0,1\}^n$ such that there is an edge between two vertices if and only if they differ in exactly one coordinate. For any graph $H$, define $\text{ex}(Q_n,H)$ to be the maximum…

Combinatorics · Mathematics 2025-01-08 Alexandr Grebennikov , João Pedro Marciano

In this Letter, we propose a new approach to process high-dimensional quantum information encoded in a photon frequency domain. In contrast to previous approaches based on nonlinear optical processes, no active control of photon energy is…

Quantum Physics · Physics 2020-07-16 Chaohan Cui , Kaushik P. Seshadreesan , Saikat Guha , Linran Fan

Let m be a positive integer and let G be a cubic graph of order 2n. We consider the problem of covering the edge-set of G with the minimum number of matchings of size m. This number is called excessive [m]-index of G in literature. The case…

Combinatorics · Mathematics 2012-10-16 Simona Bonvicini , Giuseppe Mazzuoccolo

A function $f:\{0,...,q-1\}^n\to\{0,...,q-1\}$ invertible in each argument is called a latin hypercube. A collection $(\pi_0,\pi_1,...,\pi_n)$ of permutations of $\{0,...,q-1\}$ is called an autotopism of a latin hypercube $f$ if…

Information Theory · Computer Science 2019-08-29 Denis Krotov , Vladimir Potapov

In this work, control over the precise state emitted by quantum cascade laser frequency combs through strong radio-frequency current modulation close to their repetition frequency is demonstrated. In particular, broadening of the spectrum…

Fast quantum data transmission faces several shortcomings such as the indistinguishability of some partly overlapping signals, the channel noises, and so on. Based on the encoded quantum data transmission protocol, an unconventional scheme…

Quantum Physics · Physics 2017-08-31 Weidong Tang , Sixia Yu

Let $T_{\epsilon}$ be the noise operator acting on functions on the boolean cube $\{0,1\}^n$. Let $f$ be a nonnegative function on $\{0,1\}^n$ and let $q \ge 1$. We upper bound the $\ell_q$ norm of $T_{\epsilon} f$ by the average $\ell_q$…

Information Theory · Computer Science 2019-11-13 Alex Samorodnitsky

The augmented cube $AQ_n$, proposed by Choudum and Sunitha [S. A. Choudum, V. Sunitha, Augmented cubes, Networks 40 (2) (2002) 71-84], is a $(2n-1)$-regular $(2n-1)$-connected graph $(n\ge 4)$. This paper determines that the 2-extra…

Combinatorics · Mathematics 2012-04-20 Meijie Ma , Yaxing Song , Jun-Ming Xu

The frequency noise power spectral density of a free-running quantum cascade laser frequency comb is investigated. A plateau is observed at high frequencies, attributed to the quantum noise limit set by the Schawlow-Townes formula for the…

Optics · Physics 2015-11-18 Francesco Cappelli , Gustavo Villares , Sabine Riedi , Jerome Faist

An upper bound on the feedback capacity of unifilar finite-state channels (FSCs) is derived. A new technique, called the $Q$-contexts, is based on a construction of a directed graph that is used to quantize recursively the receiver's output…

Information Theory · Computer Science 2016-04-08 Oron Sabag , Haim H. Permuter , Henry D. Pfister

A $q$-covering design $\mathbb{C}_q(n, k, r)$, $k \ge r$, is a collection $\mathcal X$ of $(k-1)$-spaces of $\mathrm{PG}(n-1, q)$ such that every $(r-1)$-space of $\mathrm{PG}(n-1, q)$ is contained in at least one element of $\mathcal X$ .…

Combinatorics · Mathematics 2019-04-30 Francesco Pavese

An optical frequency comb is a spectrum of optical radiation which consists of evenly spaced and phase-coherent narrow spectral lines and is initially invented in laser for frequency metrology purposes. A direct analogue of frequency combs…

Applied Physics · Physics 2023-06-16 Guan-Ting Xu , Mai Zhang , Yu Wang , Zhen Shen , Guang-Can Guo , Chun-Hua Dong