papers

Publications (134)

quant-ph2012

Improved lower bounds on genuine-multipartite-entanglement concurrence

Zhi-Hua Chen, Zhi-Hao Ma, Jing-Ling Chen +1

Genuine-multipartite-entanglement (GME) concurrence is a measure of genuine multipartite entanglement that generalizes the well-known notion of concurrence. We define an observable…

quant-ph2008

Weighing matrices and optical quantum computing

Steven T. Flammia, Simone Severini

Quantum computation in the one-way model requires the preparation of certain resource states known as cluster states. We describe how the construction of continuous-variable cluste…

quant-ph2012

Control by quantum dynamics on graphs

Chris Godsil, Simone Severini

We address the study of controllability of a closed quantum system whose dynamical Lie algebra is generated by adjacency matrices of graphs. We characterize a large family of graph…

quant-ph2018

Quantum linear systems algorithms: a primer

Danial Dervovic, Mark Herbster, Peter Mountney +3

The Harrow-Hassidim-Lloyd (HHL) quantum algorithm for sampling from the solution of a linear system provides an exponential speed-up over its classical counterpart. The problem of…

math.CO2008

Nondiscriminatory Propagation on Trees

Simone Severini

We consider a discrete-time dynamical process on graphs, firstly introduced in connection with a protocol for controlling large networks of spin 1/2 quantum mechanical particles [P…

quant-ph2013

Exclusivity structures and graph representatives of local complementation orbits

Adan Cabello, Matthew G. Parker, Giannicola Scarpa +1

We describe a construction that maps any connected graph G on three or more vertices into a larger graph, H(G), whose independence number is strictly smaller than its Lovász numbe…

q-bio.PE2013

A mathematical model of kinetoplastid mitochondrial gene scrambling advantage

Harry Buhrman, Peter van der Gulik, Simone Severini +1

We model and discuss advantages of pan-editing, the complex way of expressing mitochondrial genes in kinetoplastids. The rapid spread and preservation of pan-editing seems to be du…

cs.DM2018

Constructing graphs with limited resources

Danial Dervovic, Avinash Mocherla, Simone Severini

We discuss the amount of physical resources required to construct a given graph, where vertices are added sequentially. We naturally identify information -- distinct into instructi…

cond-mat.stat-mech2016

On moments of the integrated exponential Brownian motion

Francesco Caravelli, Toufik Mansour, Lorenzo Sindoni +1

We present new exact expressions for a class of moments for the geometric Brownian motion, in terms of determinants, obtained using a recurrence relation and combinatorial argument…

cond-mat.dis-nn2013

Network Transfer Entropy and Metric Space for Causality Inference

Christopher R. S. Banerji, Simone Severini, Andrew E. Teschendorff

A measure is derived to quantify directed information transfer between pairs of vertices in a weighted network, over paths of a specified maximal length. Our approach employs a gen…

quant-ph2011

The Kirchhoff's Matrix-Tree Theorem revisited: counting spanning trees with the quantum relative entropy

Vittorio Giovannetti, Simone Severini

By revisiting the Kirchhoff's Matrix-Tree Theorem, we give an exact formula for the number of spanning trees of a graph in terms of the quantum relative entropy between the maximal…

quant-ph2018

Entanglement properties of quantum grid states

Joshua Lockhart, Otfried Gühne, Simone Severini

Grid states form a discrete set of mixed quantum states that can be described by graphs. We characterize the entanglement properties of these states and provide methods to evaluate…

math.CO2006

Grid polygons from permutations and their enumeration by the kernel method

Toufik Mansour, Simone Severini

A grid polygon is a polygon whose vertices are points of a grid. We define an injective map between permutations of length n and a subset of grid polygons on n vertices, which we c…

math.CO2016

Permutation graphs and unique games

Monika Rosicka, Simone Severini

We study the value of unique games as a graph-theoretic parameter. This is obtained by labeling edges with permutations. We describe the classical value of a game as well as give a…

gr-qc2010

A quantum Bose-Hubbard model with evolving graph as toy model for emergent spacetime

Alioscia Hamma, Fotini Markopoulou, Seth Lloyd +3

We present a toy model for interacting matter and geometry that explores quantum dynamics in a spin system as a precursor to a quantum theory of gravity. The model has no a priori…

math.CO2003

On the digraph of a unitary matrix

Simone Severini

Given a matrix M of size n, a digraph D on n vertices is said to be the digraph of M, when M_{ij} is different from 0 if and only if (v_{i},v_{j}) is an arc of D. We give a necessa…

quant-ph2008

Lieb-Robinson bounds and the speed of light from topological order

Alioscia Hamma, Fotini Markopoulou, Isabeau Premont-Schwarz +1

We apply the Lieb-Robinson bounds technique to find the maximum speed of interaction in a spin model with topological order whose low-energy effective theory describes light [see X…

math.CO2006

Mediated Digraphs and Quantum Nonlocality

Gregory Gutin, Nick S. Jones, Arash Rafiey +2

A digraph D=(V,A) is mediated if, for each pair x,y of distinct vertices of D, either xy belongs to A or yx belongs to A or there is a vertex z such that both xz,yz belong to A. Fo…

math.CO2006

Hamilton Cycles in Digraphs of Unitary Matrices

Gregory Gutin, Arash Rafiey, Simone Severini +1

A set is called an {\em -set} ({\em -set}, respectively) if has at least two vertices and, for every , there exists such that…

math.CO2008

A further look into combinatorial orthogonality

Simone Severini, Ferenc Szöllősi

Strongly quadrangular matrices have been introduced in the study of the combinatorial properties of unitary matrices. It is known that if a (0, 1)-matrix supports a unitary then it…

math.CO2005

On the X-rays of permutations

Cecilia Bebeacua, Toufik Mansour, Alexander Postnikov +1

The X-ray of a permutation is defined as the sequence of antidiagonal sums in the associated permutation matrix. X-rays of permutation are interesting in the context of Discrete To…

quant-ph2009

Weight of quadratic forms and graph states

Alessandro Cosentino, Simone Severini

We prove a connection between Schmidt-rank and weight of quadratic forms. This provides a new tool for the classification of graph states based on entanglement. Our main tool arise…

cs.CC2006

The Quantum Separability Problem for Gaussian States

Stefano Mancini, Simone Severini

Determining whether a quantum state is separable or entangled is a problem of fundamental importance in quantum information science. This is a brief review in which we consider the…

quant-ph2011

Kochen-Specker Sets and the Rank-1 Quantum Chromatic Number

Giannicola Scarpa, Simone Severini

The quantum chromatic number of a graph is sandwiched between its chromatic number and its clique number, which are well known NP-hard quantities. We restrict our attention to…

quant-ph2012

Estimating entanglement monotones with a generalization of the Wootters formula

Zhi-Hua Chen, Zhi-Hao Ma, Otfried Gühne +1

Entanglement monotones, such as the concurrence, are useful tools to characterize quantum correlations in various physical systems. The computation of the concurrence involves, how…

quant-ph2014

Universal methods for extending any entanglement witness from the bipartite to the multipartite case

Bang-Hai Wang, Hai-Ru Xu, Simone Severini

Any bipartite entanglement witness can be written as , where is a quantum state, is the identity matrix, and is a non-negative number. We present a…

nlin.CD2003

Regular quantum graphs

Simone Severini, Gregor Tanner

We introduce the concept of regular quantum graphs and construct connected quantum graphs with discrete symmetries. The method is based on a decomposition of the quantum propagator…

q-bio.MN2013

Cellular network entropy as the energy potential in Waddington's differentiation landscape

Christopher R. S. Banerji, Diego Miranda-Saavedra, Simone Severini +4

Differentiation is a key cellular process in normal tissue development that is significantly altered in cancer. Although molecular signatures characterising pluripotency and multip…

quant-ph2006

The laplacian of a graph as a density matrix: a basic combinatorial approach to separability of mixed states

Samuel L. Braunstein, Sibasish Ghosh, Simone Severini

We study entanglement properties of mixed density matrices obtained from combinatorial Laplacians. This is done by introducing the notion of the density matrix of a graph. We chara…

quant-ph2014

Graph-Theoretic Approach to Quantum Correlations

Adan Cabello, Simone Severini, Andreas Winter

Correlations in Bell and noncontextuality inequalities can be expressed as a positive linear combination of probabilities of events. Exclusive events can be represented as adjacent…

quant-ph2006

The disentangling power of unitaries

Lieven Clarisse, Sibasish Ghosh, Simone Severini +1

We define the disentangling power of a unitary operator in a similar way as the entangling power defined by Zanardi, Zalka and Faoro [PRA, 62, 030301]. A general formula is derived…

cs.DM2003

On a composition of digraphs

Simone Severini

Many "good" topologies for interconnection networks are based on line digraphs of regular digraphs. These digraphs support unitary matrices. We propose the property "being the digr…

hep-th2008

Hidden entanglement at the Planck scale: loss of unitarity and the information paradox

Michele Arzano, Alioscia Hamma, Simone Severini

We discuss how relaxing the requirement of locality for quantum fields can equip the Hilbert space of the theory with a richer structure in its multi-particle sector. A physical co…

quant-ph2018

Universal discriminative quantum neural networks

Hongxiang Chen, Leonard Wossnig, Simone Severini +2

Quantum mechanics fundamentally forbids deterministic discrimination of quantum states and processes. However, the ability to optimally distinguish various classes of quantum data…

math.CO2006

On the structure of the adjacency matrix of the line digraph of a regular digraph

Simone Severini

We show that the adjacency matrix M of the line digraph of a d-regular digraph D on n vertices can be written as M=AB, where the matrix A is the Kronecker product of the all-ones m…

math.CO2015

Orthogonal Representations, Projective Rank, and Fractional Minimum Positive Semidefinite Rank: Connections and New Directions

Leslie Hogben, Kevin F. Palmowski, David E. Roberson +1

Fractional minimum positive semidefinite rank is defined from -fold faithful orthogonal representations and it is shown that the projective rank of any graph equals the fraction…

math.OA2016

Estimating quantum chromatic numbers

Vern I. Paulsen, Simone Severini, Daniel Stahlke +2

We develop further the new versions of quantum chromatic numbers of graphs introduced by the first and fourth authors. We prove that the problem of computation of the commuting qua…

quant-ph2005

Two-colorable graph states with maximal Schmidt measure

Simone Severini

The Schmidt measure was introduced by Eisert and Briegel for quantifying the degree of entanglement of multipartite quantum systems [Phys. Rev. A 64, 022306 (2001)]. Although gener…

q-bio.MN2012

On dynamic network entropy in cancer

James West, Ginestra Bianconi, Simone Severini +1

The cellular phenotype is described by a complex network of molecular interactions. Elucidating network properties that distinguish disease from the healthy cellular state is there…

physics.data-an2010

A characterization of horizontal visibility graphs and combinatorics on words

Gregory Gutin, Toufik Mansour, Simone Severini

An Horizontal Visibility Graph (for short, HVG) is defined in association with an ordered set of non-negative reals. HVGs realize a methodology in the analysis of time series, thei…

math.CO2009

Tensor 2-sums and entanglement

Sandi Klavzar, Simone Severini

To define a minimal mathematical framework for isolating some of the characteristic properties of quantum entanglement, we introduce a generalization of the tensor product of graph…

quant-ph2018

Hierarchical quantum classifiers

Edward Grant, Marcello Benedetti, Shuxiang Cao +5

Quantum circuits with hierarchical structure have been used to perform binary classification of classical data encoded in a quantum state. We demonstrate that more expressive circu…

quant-ph2011

Zero forcing, linear and quantum controllability for systems evolving on networks

Daniel Burgarth, Domenico D'Alessandro, Leslie Hogben +2

We study the dynamics of systems on networks from a linear algebraic perspective. The control theoretic concept of controllability describes the set of states that can be reached f…

quant-ph2008

An application of the Deutsch-Josza algorithm to formal languages and the word problem in groups

Michael Batty, Andrea Casaccino, Andrew J. Duncan +2

We adapt the Deutsch-Josza algorithm to the context of formal language theory. Specifically, we use the algorithm to distinguish between trivial and nontrivial words in groups give…

quant-ph2003

The underlying digraph of a coined quantum random walk

Simone Severini

We give a characterization of the line digraph of a regular digraph. We make use of the characterization, to show that the underlying digraph of a coined quantum random walk is a l…

math.CO2013

Interpreting the von Neumann entropy of graph Laplacians, and coentropic graphs

Niel de Beaudrap, Vittorio Giovannetti, Simone Severini +1

For any graph, we define a rank-1 operator on a bipartite tensor product space, with components associated to the set of vertices and edges respectively. We show that the partial t…

cond-mat.dis-nn2010

The Shannon and the Von Neumann entropy of random networks with heterogeneous expected degree

Kartik Anand, Ginestra Bianconi, Simone Severini

Entropic measures of complexity are able to quantify the information encoded in complex network structures. Several entropic measures have been proposed in this respect. Here we st…

math.CO2009

Rational Orthogonal versus Real Orthogonal

Dragomir Z. Djokovic, Simone Severini, Ferenc Szollosi

The main question we raise here is the following one: given a real orthogonal n by n matrix X, is it true that there exists a rational orthogonal matrix Y having the same zero-patt…

quant-ph2012

A Generalization of Kochen-Specker Sets Relates Quantum Coloring to Entanglement-Assisted Channel Capacity

Laura Mancinska, Giannicola Scarpa, Simone Severini

We introduce two generalizations of Kochen-Specker (KS) sets: projective KS sets and generalized KS sets. We then use projective KS sets to characterize all graphs for which the ch…

quant-ph2010

Entanglement and area law with a fractal boundary in a topologically ordered phase

Alioscia Hamma, Daniel A. Lidar, Simone Severini

Quantum systems with short range interactions are known to respect an area law for the entanglement entropy: the von Neumann entropy associated to a bipartition scales with the…

hep-th2008

Quantum Graphity: a model of emergent locality

Tomasz Konopka, Fotini Markopoulou, Simone Severini

Quantum graphity is a background independent model for emergent locality, spatial geometry and matter. The states of the system correspond to dynamical graphs on N vertices. At hig…

cs.LO2026

The Network Structure of Mathlib

Xinze Li, Nanyun Peng, Simone Severini +1

The ongoing development of Lean 4's Mathlib has produced a macroscopic structural complexity that interweaves logical, mathematical, and infrastructural dependencies. We present a…

cond-mat.dis-nn2011

Approximate entropy of network parameters

James West, Lucas Lacasa, Simone Severini +1

We study the notion of approximate entropy within the framework of network theory. Approximate entropy is an uncertainty measure originally proposed in the context of dynamical sys…

quant-ph2016

Combinatorial Entanglement

Joshua Lockhart, Simone Severini

We present new combinatorial objects, which we call grid-labelled graphs, and show how these can be used to represent the quantum states arising in a scenario which we refer to as…

math.CO2013

An example of graph limits of growing sequences of random graphs

Svante Janson, Simone Severini

We consider a class of growing random graphs obtained by creating vertices sequentially one by one: at each step, we choose uniformly the neighbours of the newly created vertex; it…

cs.AI2026

LEAP: Supercharging LLMs for Formal Mathematics with Agentic Frameworks

Po-Nien Kung, Linfeng Song, Dawsen Hwang +10

Large Language Models (LLMs) exhibit strong informal mathematical reasoning but struggle to generate mechanically verifiable proofs in formal languages like Lean. We present LEAP,…

math.CO2016

Note on von Neumann and Rényi entropies of a Graph

Michael Dairyko, Leslie Hogben, Jephian C. -H. Lin +4

We conjecture that all connected graphs of order have von Neumann entropy at least as great as the star and prove this for almost all graphs of order . We show t…

quant-ph2018

Quantum Walk Search on Kronecker Graphs

Thomas G. Wong, Konstantin Wünscher, Joshua Lockhart +1

Kronecker graphs, obtained by repeatedly performing the Kronecker product of the adjacency matrix of an "initiator" graph with itself, have risen in popularity in network science d…

quant-ph2010

Matrix permanent and quantum entanglement of permutation invariant states

Tzu-Chieh Wei, Simone Severini

We point out that a geometric measure of quantum entanglement is related to the matrix permanent when restricted to permutation invariant states. This connection allows us to inter…

quant-ph2015

Linear game non-contextuality and Bell inequalities - a graph-theoretic approach

Piotr Gnaciński, Monika Rosicka, Ravishankar Ramanathan +4

We study the classical and quantum values of one- and two-party linear games, an important class of unique games that generalizes the well-known XOR games to the case of non-binary…

quant-ph2012

Number-Theoretic Nature of Communication in Quantum Spin Systems

Chris Godsil, Stephen Kirkland, Simone Severini +1

The last decade has witnessed substantial interest in protocols for transferring information on networks of quantum mechanical objects. A variety of control methods and network top…

math.CO2008

Partial transpose of permutation matrices

Qing-Hu Hou, Toufik Mansour, Simone Severini

The partial transpose of a block matrix M is the matrix obtained by transposing the blocks of M independently. We approach the notion of partial transpose from a combinatorial poin…

quant-ph2014

Hearing the Shape of the Ising Model with a Programmable Superconducting-Flux Annealer

Walter Vinci, Klas Markström, Sergio Boixo +4

Two objects can be distinguished if they have different measurable properties. Thus, distinguishability depends on the Physics of the objects. In considering graphs, we revisit the…

cs.CV2019

Graph Cut Segmentation Methods Revisited with a Quantum Algorithm

Lisa Tse, Peter Mountney, Paul Klein +1

The design and performance of computer vision algorithms are greatly influenced by the hardware on which they are implemented. CPUs, multi-core CPUs, FPGAs and GPUs have inspired n…

math.CO2008

Enumeration of -noncrossing partitions

Toufik Mansour, Simone Severini

A set partition is said to be -noncrossing if it avoids the pattern . We find an explicit formula for the ordinary generating function of the number of $(k,d…

quant-ph2018

Learning hard quantum distributions with variational autoencoders

Andrea Rocchetto, Edward Grant, Sergii Strelchuk +2

Studying general quantum many-body systems is one of the major challenges in modern physics because it requires an amount of computational resources that scales exponentially with…

quant-ph2018

Quantum machine learning: a classical perspective

Carlo Ciliberto, Mark Herbster, Alessandro Davide Ialongo +4

Recently, increased computational power and data availability, as well as algorithmic advances, have led machine learning techniques to impressive results in regression, classifica…

quant-ph2010

(Non-)Contextuality of Physical Theories as an Axiom

Adan Cabello, Simone Severini, Andreas Winter

We show that the noncontextual inequality proposed by Klyachko et al. [Phys. Rev. Lett. 101, 020403 (2008)] belongs to a broader family of inequalities, one associated to each comp…

quant-ph2007

Some families of density matrices for which separability is easily tested

Samuel L. Braunstein, Sibasish Ghosh, Toufik Mansour +2

We reconsider density matrices of graphs as defined in [quant-ph/0406165]. The density matrix of a graph is the combinatorial laplacian of the graph normalized to have unit trace.…

quant-ph2013

Locality for quantum systems on graphs depends on the number field

H. Tracy Hall, Simone Severini

Adapting a definition of Aaronson and Ambainis [Theory Comput. 1 (2005), 47--79], we call a quantum dynamics on a digraph "saturated Z-local" if the nonzero transition amplitudes s…

math.CO2018

Weak Modular Product of Bipartite Graphs, Bicliques and Isomorphism

Danial Dervovic, Simone Severini

A 1978 theorem of Kozen states that two graphs on vertices are isomorphic if and only if there is a clique of size in the weak modular product between the two graphs. Restr…

math.CO2010

On the degeneracy of topological phases

Stephen P. Jordan, Toufik Mansour, Simone Severini

The ground state degeneracy of an topological phase with quasiparticle excitations is relevant quantity for quantum computation, condensed matter physics, and knot th…

math.CO2013

Sabidussi Versus Hedetniemi for Three Variations of the Chromatic Number

Chris Godsil, David Roberson, Robert Šámal +1

We investigate vector chromatic number, Lovasz theta of the complement, and quantum chromatic number from the perspective of graph homomorphisms. We prove an analog of Sabidussi's…

quant-ph2007

Parameters of Integral Circulant Graphs and Periodic Quantum Dynamics

Nitin Saxena, Simone Severini, Igor Shparlinski

The intention of the paper is to move a step towards a classification of network topologies that exhibit periodic quantum dynamics. We show that the evolution of a quantum system,…

quant-ph2015

Graph-theoretical Bounds on the Entangled Value of Non-local Games

André Chailloux, Laura Mančinska, Giannicola Scarpa +1

We introduce a novel technique to give bounds to the entangled value of non-local games. The technique is based on a class of graphs used by Cabello, Severini and Winter in 2010. T…

quant-ph2006

On the quantum chromatic number of a graph

Peter J. Cameron, Ashley Montanaro, Michael W. Newman +2

We investigate the notion of quantum chromatic number of a graph, which is the minimal number of colours necessary in a protocol in which two separated provers can convince an inte…

econ.GN2022

The impact of CAP subsidies on the productivity of cereal farms in six European countries

Luigi Biagini, Federico Antonioli, Simone Severini

Total factor productivity (TFP) is a key determinant of farm development, a sector that receives substantial public support. The issue has taken on great importance today, where th…

quant-ph2017

Quantum and non-signalling graph isomorphisms

Albert Atserias, Laura Mančinska, David E. Roberson +3

We introduce a two-player nonlocal game, called the -isomorphism game, where classical players can win with certainty if and only if the graphs and are isomorphic. W…

cs.DM2011

Logic circuits from zero forcing

Daniel Burgarth, Vittorio Giovannetti, Leslie Hogben +2

We design logic circuits based on the notion of zero forcing on graphs; each gate of the circuits is a gadget in which zero forcing is performed. We show that such circuits can eva…

quant-ph2006

A generalization of boson normal ordering

Toufik Mansour, Matthias Schork, Simone Severini

In this paper we define generalizations of boson normal ordering. These are based on the number of contractions whose vertices are next to each other in the linear representation o…

math.CO2004

Quadrangularity in Tournaments

J. Richard Lundgren, Simone Severini, Dustin J. Stewart

The pattern of a matrix M is a (0,1)-matrix which replaces all non-zero entries of M with a 1. There are several contexts in which studying the patterns of orthogonal matrices can…

quant-ph2013

Quantum channels from association schemes

Tao Feng, Simone Severini

We propose in this note the study of quantum channels from association schemes. This is done by interpreting the -matrices of a scheme as the Kraus operators of a channel. W…

quant-ph2009

Quantum state transfer through a qubit network with energy shifts and fluctuations

Andrea Casaccino, Seth Lloyd, Stefano Mancini +1

We study quantum state transfer through a qubit network modeled by spins with XY interaction, when relying on a single excitation. We show that it is possible to achieve perfect tr…

math.CO2002

On the Cayley digraphs that are patterns of unitary matrices

Simone Severini

A digraph D is the pattern of a matrix M when D has an arc ij if and only if the ij-th entry of M is nonzero. Study the relationship between unitary matrices and their patterns is…

cs.LO2017

Generalized Satisfiability Problems via Operator Assignments

Albert Atserias, Phokion G. Kolaitis, Simone Severini

Schaefer introduced a framework for generalized satisfiability problems on the Boolean domain and characterized the computational complexity of such problems. We investigate an alg…

econ.GN2023

The direct and indirect effect of CAP support on farm income enhancement:a farm-based econometric analysis

Simone Severini, Luigi Biagini

We assess the correlation between CAP support provided to farmers and their income and use of capital and labour in the first year of the new CAP regime. This is done applying thre…

math.CO2009

Diffusion on an Ising chain with kinks

Alioscia Hamma, Toufik Mansour, Simone Severini

We count the number of histories between the two degenerate minimum energy configurations of the Ising model on a chain, as a function of the length n and the number d of kinks tha…

quant-ph2014

Randomized Graph States and their Entanglement Properties

Jun-Yi Wu, Matteo Rossi, Hermann Kampermann +4

We introduce a class of mixed multiqubit states, that corresponds to a randomized version of graph states. Such states arise when a graph state is prepared with noisy or imperfect…

quant-ph2004

Quantum Algorithms and Covering Spaces

Tobias J. Osborne, Simone Severini

In this paper we isolate the combinatorial property responsible (at least in part) for the computational speedups recently observed in some quantum walk algorithms. We find that co…

q-bio.MN2015

Increased signaling entropy in cancer requires the scale-free property of protein interaction networks

Andrew E. Teschendorff, Christopher R. S. Banerji, Simone Severini +2

One of the key characteristics of cancer cells is an increased phenotypic plasticity, driven by underlying genetic and epigenetic perturbations. However, at a systems-level it is u…

quant-ph2015

A combinatorial criterion for k-separability of multipartite Dicke states

Zhihua Chen, Zhihao Ma, Ting Gao +1

We derive a combinatorial criterion for detecting k-separability of N-partite Dicke states. The criterion is efficiently computable and implementable without full state tomography.…

quant-ph2004

Estimation of pure qubits on circles

Samuel L. Braunstein, Sibasish Ghosh, Simone Severini

Gisin and Popescu [PRL, 83, 432 (1999)] have shown that more information about their direction can be obtained from a pair of anti-parallel spins compared to a pair of parallel spi…

quant-ph2011

Spin systems dynamics and faults detection in threshold networks

Steve Kirkland, Simone Severini

We consider an agent on a fixed but arbitrary node of a known threshold network, with the task of detecting an unknown missing link/node. We obtain analytic formulas for the probab…

math.CO2009

A note on observables for counting trails and paths in graphs

Fotini Markopoulou, Simone Severini

We point out that the total number of trails and the total number of paths of given length, between two vertices of a simple undirected graph, are obtained as expectation values of…

quant-ph2020

Approximating Hamiltonian dynamics with the Nyström method

Alessandro Rudi, Leonard Wossnig, Carlo Ciliberto +3

Simulating the time-evolution of quantum mechanical systems is BQP-hard and expected to be one of the foremost applications of quantum computers. We consider classical algorithms f…

quant-ph2010

Entanglement manipulation via dynamics in multiple quantum spin systems

Andrea Casaccino, Stefano Mancini, Simone Severini

We study manipulation of entanglement between two identical networks of quantum mechanical particles. Firstly, we reduce the problem of entanglement transfer to the problem of quan…

quant-ph2008

Extrema of discrete Wigner functions and applications

Andrea Casaccino, Ernesto F. Galvao, Simone Severini

We study the class of discrete Wigner functions proposed by Gibbons et al. [Phys. Rev. A 70, 062101 (2004)] to describe quantum states using a discrete phase-space based on finite…

math.CO2009

Counting paths in Bratteli diagrams for SU(2)_k

Toufik Mansour, Simone Severini

It is known that the Hilbert space dimensionality for quasiparticles in an SU(2)_k Chern-Simons-Witten theory is given by the number of directed paths in certain Bratteli diagrams.…

physics.soc-ph2013

Co-evolution of networks and quantum dynamics: a generalization of preferential attachment

Vincenzo Nicosia, Takuya Machida, Richard Wilson +4

We propose a model of network growth in which the network is co-evolving together with the dynamics of a quantum mechanical system, namely a quantum walk taking place over the netw…

quant-ph2006

Universal quantum computation with unlabeled qubits

Simone Severini

We show that an n-th root of the Walsh-Hadamard transform (obtained from the Hadamard gate and a cyclic permutation of the qubits), together with two diagonal matrices, namely a lo…