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Revisiting Deniability in Quantum Key Exchange via Covert Communication and Entanglement Distillation
http://hdl.handle.net/10993/36653
Title: Revisiting Deniability in Quantum Key Exchange via Covert Communication and Entanglement Distillation
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<br/>Author, co-author: Atashpendar, Arash; Policharla, Guru Vamsi; Roenne, Peter; Ryan, Peter
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<br/>Abstract: We revisit the notion of deniability in quantum key exchange (QKE), a topic that remains largely unexplored. In the only work on this subject by Donald Beaver, it is argued that QKE is not necessarily deniable due to an eavesdropping attack that limits key equivocation. We provide more insight into the nature of this attack and how it extends to other constructions such as QKE obtained from uncloneable encryption. We then adopt the framework for quantum authenticated key exchange, developed by Mosca et al., and extend it to introduce the notion of coercer-deniable QKE, formalized in terms of the indistinguishability of real and fake coercer views. Next, we apply results from a recent work by Arrazola and Scarani on covert quantum communication to establish a connection between covert QKE and deniability. We propose DC-QKE, a simple deniable covert QKE protocol, and prove its deniability via a reduction to the security of covert QKE. Finally, we consider how entanglement distillation can be used to enable information-theoretically deniable protocols for QKE and tasks beyond key exchange.Magnetic neutron scattering on bulk ferromagnets
http://hdl.handle.net/10993/36639
Title: Magnetic neutron scattering on bulk ferromagnets
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<br/>Author, co-author: Michels, AndreasMagnetic SANS is different than nonmagnetic SANS
http://hdl.handle.net/10993/36638
Title: Magnetic SANS is different than nonmagnetic SANS
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<br/>Author, co-author: Michels, AndreasModels of Objective Chance: An Analysis through Examples
http://hdl.handle.net/10993/36622
Title: Models of Objective Chance: An Analysis through Examples
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<br/>Author, co-author: Bana, GergelyOn the Formal Consistency of the Principal Principle
http://hdl.handle.net/10993/36621
Title: On the Formal Consistency of the Principal Principle
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<br/>Author, co-author: Bana, GergelyMaintenance location routing for rolling stock under line and fleet planning uncertainty
http://hdl.handle.net/10993/36600
Title: Maintenance location routing for rolling stock under line and fleet planning uncertainty
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<br/>Author, co-author: Arts, Joachim; Tönissen, Denise; Shen, Zuo-JunAstrophysical aspects of dark matter direct detection
http://hdl.handle.net/10993/36585
Title: Astrophysical aspects of dark matter direct detection
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<br/>Author, co-author: Magni, StefanoOn the use of the escape speed estimates in setting dark matter direct detection limits
http://hdl.handle.net/10993/36584
Title: On the use of the escape speed estimates in setting dark matter direct detection limits
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<br/>Author, co-author: Magni, Stefano; Lavalle, J.
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<br/>Abstract: The knowledge of the high velocity tail of the WIMP velocity distribution has a strong impact on the way direct detection (DD) may constrain or discover light WIMPs in the GeV mass range. Recently, there have been important observational efforts to estimate the so-called Galactic escape speed at the position of the Earth, for instance the analysis published in early 2014 by the RAVE Collaboration ' , which is of interest in the perspective of reducing the astrophysical uncertainties in DD. Nevertheless, these new estimates cannot be used blindly as they rely on assumptions in the dark halo modeling, which induce tight correlations between the escape speed and other local astrophysical parameters (e.g. the local circular speed and dark matter density). We make a self-consistent study of the implications of the RAVE results on DD assuming isotropic DM velocity distributions, both Maxwellian and ergodic. Taking as reference the experimental sensitivities currently achieved by LUX, CRESST2, and SuperCDMS, we show that the DD constraints on WIMPs (and associated uncertainties) are slightly stronger (moderate).
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<br/>Commentary: pages: 555-558Revisiting the escape speed impact on dark matter direct detection
http://hdl.handle.net/10993/36583
Title: Revisiting the escape speed impact on dark matter direct detection
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<br/>Author, co-author: Magni, Stefano; Lavalle, J.
<br/>
<br/>Abstract: The knowledge of the high velocity tail of the WIMP (Weakly Interacting Massive Particles)
velocity distribution has a strong impact on the way dark matter direct detection (DMDD) may
constrain or discover light WIMPs in the GeV mass range. Recently, there have been important
observational efforts to estimate the Galactic escape speed at the position of the Earth, like for instance
the analysis published in early 2014 by the RAVE Collaboration (Piffl et al., 2014), which is
of interest in the perspective of reducing the astrophysical uncertainties in DMDD. Nevertheless,
these new estimates cannot be used blindly as they rely on assumptions on the Milky Way mass
distribution, which induce tight correlations between the escape speed and other local astrophysical
parameters (circular speed and dark matter density). We make a self-consistent study of the
implications of the RAVE results on DMDD assuming isotropic DM velocity distributions, both
Maxwellian and ergodic. Taking as reference the experimental sensitivities currently achieved
by LUX, CRESST2, and SuperCDMS, we show that the uncertainties inferred for the exclusion
curves in the low WIMP mass region are moderate, ranging from 10% to 20% , and that
the RAVE results imply large values of r , and so correspond to exclusion curves that are more
constraining than the standard ones by 40%.Making sense of the local Galactic escape speed estimates in direct dark matter searches
http://hdl.handle.net/10993/36582
Title: Making sense of the local Galactic escape speed estimates in direct dark matter searches
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<br/>Author, co-author: Lavalle, Julien; Magni, Stefano
<br/>
<br/>Abstract: Direct detection (DD) of dark matter (DM) candidates in the ≲10 GeV mass range is very sensitive to the tail of their velocity distribution. The important quantity is the maximum weakly interacting massive particle speed in the observer's rest frame, i.e. in average the sum of the local Galactic escape speed v[SUB]esc[/SUB] and of the circular velocity of the Sun v[SUB]c[/SUB]. While the latter has been receiving continuous attention, the former is more difficult to constrain. The RAVE Collaboration has just released a new estimate of v[SUB]esc[/SUB] [T. Piffl et al., Astron. Astrophys. 562, A91 (2014)] that supersedes the previous one [M. C. Smith, et al. Mon. Not. R. Astron. Soc. 379, 755 (2007)], which is of interest in the perspective of reducing the astrophysical uncertainties in DD. Nevertheless, these new estimates cannot be used blindly as they rely on assumptions in the dark halo modeling which induce tight correlations between the escape speed and other local astrophysical parameters. We make a self-consistent study of the implications of the RAVE results on DD assuming isotropic DM velocity distributions, both Maxwellian and ergodic. Taking as references the experimental sensitivities currently achieved by LUX, CRESST-II, and SuperCDMS, we show that (i) the exclusion curves associated with the best-fit points of P14 may be more constraining by up to ˜40 % with respect to standard limits, because the underlying astrophysical correlations induce a larger local DM density, and (ii) the corresponding relative uncertainties inferred in the low weakly interacting massive particle mass region may be moderate, down to 10-15% below 10 GeV. We finally discuss the level of consistency of these results with other independent astrophysical constraints. This analysis is complementary to others based on rotation curves.Backreaction and the Covariant Formalism of General Relativity
http://hdl.handle.net/10993/36581
Title: Backreaction and the Covariant Formalism of General Relativity
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<br/>Author, co-author: Magni, Stefano
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<br/>Abstract: This thesis is a review of backreaction, which is a possible alternative to dark energy and modified gravity. We describe in detail the 3+1 covariant formalism and Frobenius' theorem. We present the averaging procedure developed by Buchert, the Buchert equations and the generalization of these equations to the case of general matter. We then generalize to arbitrary number of spatial dimensions. We focus on the case of 2+1 dimensions, where the relation between the topology and the geometry of a surface imposes a global constraint on backreaction.
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<br/>Commentary: 96 pages, 3 figures, master thesis; supervisors: S.R\"as\"anen and M.CarforaDo the relative patterns of green space within cities impact carbon uptake? A European scale analysis
http://hdl.handle.net/10993/36570
Title: Do the relative patterns of green space within cities impact carbon uptake? A European scale analysis
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<br/>Author, co-author: Boura, Marlène Delphine FabienneA hyper-reduction method using adaptivity to cut the assembly costs of reduced order models
http://hdl.handle.net/10993/36557
Title: A hyper-reduction method using adaptivity to cut the assembly costs of reduced order models
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<br/>Author, co-author: Hale, Jack; Schenone, Elisa; Baroli, Davide; Beex, Lars; Bordas, Stéphane
<br/>
<br/>Abstract: At every iteration or timestep of the online phase of some reduced-order modelling schemes, large linear systems must be assembled and then projected onto a reduced order basis of small dimension. The projected small linear systems are cheap to solve, but assembly and projection are now the dominant computational cost. In this paper we introduce a new hyper-reduction strategy called reduced assembly (RA) that drastically cuts these costs. RA consists of a triangulation adaptation algorithm that uses a local error indicator to con- struct a reduced assembly triangulation specially suited to the reduced order basis. Crucially, this reduced assembly triangulation has fewer cells than the original one, resulting in lower assembly and projection costs. We demonstrate the efficacy of RA on a Galerkin-POD type reduced order model (RAPOD). We show performance increases of up to five times over the baseline Galerkin-POD method on a non-linear reaction-diffusion problem solved with a semi-implicit time-stepping scheme and up to seven times for a 3D hyperelasticity problem solved with a continuation Newton-Raphson algorithm. The examples are implemented in the DOLFIN finite element solver using PETSc and SLEPc for linear algebra. Full code and data files to produce the results in this paper are provided as supplementary material.Collective Power: Minimal Model for Thermodynamics of Nonequilibrium Phase Transitions
http://hdl.handle.net/10993/36553
Title: Collective Power: Minimal Model for Thermodynamics of Nonequilibrium Phase Transitions
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<br/>Author, co-author: Herpich, Tim; Thingna, Juzar; Esposito, Massimiliano
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<br/>Abstract: We propose a thermodynamically consistent minimal model to study synchronization which is
made of driven and interacting three-state units. This system exhibits at the mean-field level two
bifurcations separating three dynamical phases: a single stable fixed point, a stable limit cycle
indicative of synchronization, and multiple stable fixed points. These complex emergent dynamical
behaviors are understood at the level of the underlying linear Markovian dynamics in terms of
metastability, i.e. the appearance of gaps in the upper real part of the spectrum of the Markov
generator. Stochastic thermodynamics is used to study the dissipated work across dynamical phases
as well as across scales. This dissipated work is found to be reduced by the attractive interactions
between the units and to nontrivially depend on the system size. When operating as a work-to-
work converter, we find that the maximum power output is achieved far-from-equilibrium in the
synchronization regime and that the efficiency at maximum power is surprisingly close to the linear
regime prediction. Our work shows the way towards building a thermodynamics of nonequilibrium
phase transitions in conjunction to bifurcation theory.How does the relative spatial pattern of green within cities impact carbon uptake? A European scale analysis
http://hdl.handle.net/10993/36552
Title: How does the relative spatial pattern of green within cities impact carbon uptake? A European scale analysis
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<br/>Author, co-author: Boura, Marlène Delphine Fabienne; Caruso, GeoffreyAn equation-free, nested, concurrent multiscale approach without scale-separation
http://hdl.handle.net/10993/36551
Title: An equation-free, nested, concurrent multiscale approach without scale-separation
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<br/>Author, co-author: Beex, Lars; Kerfriden, PierreHomotopical algebraic context over differential operators
http://hdl.handle.net/10993/36541
Title: Homotopical algebraic context over differential operators
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<br/>Author, co-author: Di Brino, Gennaro; Pistalo, Damjan; Poncin, NorbertOn the Hilbert eigenvariety at exotic and CM classical weight 1 points
http://hdl.handle.net/10993/36507
Title: On the Hilbert eigenvariety at exotic and CM classical weight 1 points
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<br/>Author, co-author: Deo, Shaunak; Betina, Adel; Fite, FrancescNewforms mod p in squarefree level with applications to Monsky's Hecke-stable filtrations (with an appendix by Alexandru Ghitza)
http://hdl.handle.net/10993/36506
Title: Newforms mod p in squarefree level with applications to Monsky's Hecke-stable filtrations (with an appendix by Alexandru Ghitza)
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<br/>Author, co-author: Deo, Shaunak; Medvedovsky, AnnaEffect of increasing the ramification on pseudo-deformation rings
http://hdl.handle.net/10993/36505
Title: Effect of increasing the ramification on pseudo-deformation rings
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<br/>Author, co-author: Deo, Shaunak