174,701 research outputs found
Violation of a Leggett-Garg inequality with ideal non-invasive measurements
No full textThe quantum superposition principle states that an entity can exist in two different states simultaneously, counter to our 'classical' intuition. Is it possible to understand a given system's behaviour without such a concept? A test designed by Leggett and Garg can rule out this possibility. The test, originally intended for macroscopic objects, has been implemented in various systems. However to date no experiment has employed the 'ideal negative result' measurements that are required for the most robust test. Here we introduce a general protocol for these special measurements using an ancillary system, which acts as a local measuring device but which need not be perfectly prepared. We report an experimental realization using spin-bearing phosphorus impurities in silicon. The results demonstrate the necessity of a non-classical picture for this class of microscopic system. Our procedure can be applied to systems of any size, whether individually controlled or in a spatial ensemble.</p
Violation of Leggett-Garg inequalities for quantum-classical hybrids
No full textViolation of Leggett{Garg inequalities can serve as a signature of a failure of
(macroscopic) realism. We investigate violation of the simplest Leggett{Garg inequality for
a qubit coupled to an integer j spin (angular momentum). Such a system e ectively reveals
quantum{classical hybrid behavior in the limit of large j values. We show that a maximal
violation of the Leggett{ Garg inequality is larger for quantum{classical hybrids than for fully
quantum systems
Comment on 'A scattering quantum circuit for measuring Bell's time inequality:a nuclear magnetic resonance demonstration using maximally mixed states'
No full textA recent paper by Souza, Oliveira and Sarthour (SOS) reports the experimental violation of a Leggett-Garg (LG) inequality (sometimes referred to as a temporal Bell inequality). The inequality tests for quantum mechanical superposition: if the inequality is violated, the dynamics cannot be explained by a large class of classical theories under the heading of macrorealism. Experimental tests of the LG inequality are beset by the difficulty of carrying out the necessary so-called 'non-invasive' measurements (which for the macrorealist will extract information from a system of interest without disturbing it). SOS argue that they nevertheless achieve this difficult goal by putting the system in a maximally mixed state. The system then allegedly undergoes no perturbation during their experiment. Unfortunately, the method is ultimately unconvincing to a skeptical macrorealist and so the conclusions drawn by SOS are unjustified.</p
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
Quantum Nondemolition Measurement Enables Macroscopic Leggett-Garg Tests
No full textWe show how a test of macroscopic realism based on Leggett-Garg inequalities (LGIs) can be performed in a macroscopic system. Using a continuous-variable approach, we consider quantum nondemolition (QND) measurements applied to atomic ensembles undergoing magnetically driven coherent oscillation. We identify measurement schemes requiring only Gaussian states as inputs and giving a significant LGI violation with realistic experimental parameters and imperfections. The predicted violation is shown to be due to true quantum effects rather than to a classical invasivity of the measurement. Using QND measurements to tighten the “clumsiness loophole” forces the stubborn macrorealist to recreate quantum backaction in his or her account of measurement
Learning Generalized Depth Three Arithmetic Circuits in the Non-Degenerate Case
No full textConsider a homogeneous degree d polynomial f = T₁ + ⋯ + T_s, T_i = g_i(_{i,1}, …, _{i, m}) where g_i’s are homogeneous m-variate degree d polynomials and _{i,j}’s are linear polynomials in n variables. We design a (randomized) learning algorithm that given black-box access to f, computes black-boxes for the T_i’s. The running time of the algorithm is poly(n, m, d, s) and the algorithm works under some non-degeneracy conditions on the linear forms and the g_i’s, and some additional technical assumptions n ≥ (md)², s ≤ n^{d/4}. The non-degeneracy conditions on _{i,j}’s constitute non-membership in a variety, and hence are satisfied when the coefficients of _{i,j}’s are chosen uniformly and randomly from a large enough set. The conditions on g_i’s are satisfied for random polynomials and also for natural polynomials common in the study of arithmetic complexity like determinant, permanent, elementary symmetric polynomial, iterated matrix multiplication. A particularly appealing algorithmic corollary is the following: Given black-box access to an f = Det_r(L^(1)) + … + Det_r(L^(s)), where L^(k) = (_{i,j}^(k))_{i,j} with _{i,j}^(k)’s being linear forms in n variables chosen randomly, there is an algorithm which in time poly(n, r) outputs matrices (M^(k))_k of linear forms s.t. there exists a permutation π: [s] → [s] with Det_r(M^(k)) = Det_r(L^(π(k))).
Our work follows the works [Neeraj Kayal and Chandan Saha, 2019; Garg et al., 2020] which use lower bound methods in arithmetic complexity to design average case learning algorithms. It also vastly generalizes the result in [Neeraj Kayal and Chandan Saha, 2019] about learning depth three circuits, which is a special case where each g_i is just a monomial. At the core of our algorithm is the partial derivative method which can be used to prove lower bounds for generalized depth three circuits. To apply the general framework in [Neeraj Kayal and Chandan Saha, 2019; Garg et al., 2020], we need to establish that the non-degeneracy conditions arising out of applying the framework with the partial derivative method are satisfied in the random case. We develop simple but general and powerful tools to establish this, which might be useful in designing average case learning algorithms for other arithmetic circuit models
Understanding variability in performance of type il cements: insights from Raman imaging
No full textPortland-limestone cement (PLC), designated as Type IL under ASTM C595, has emerged as a lower-carbon alternative to ordinary Portland cement (OPC). By replacing up to 15% of clinker with finely ground limestone, PLC reduces calcination-related emissions and offers an average greenhouse gas reduction of more than 8%. Although this environmental benefit has accelerated the adoption of PLC across North America, significant performance variability has been reported in the field, including reductions in 28-day strength, increased water demand, and inconsistent set behavior. The origins of this performance variability remain insufficiently understood because commercial PLCs differ in both clinker phase composition and fineness.
This thesis investigates twelve commercial Type IL cements to quantify their performance variability and understand how their physical and chemical properties influence it. Multimodal characterization was applied, combining compressive strength testing and open porosity measurements (at 1, 3, 7, and 28 days of hydration), isothermal calorimetry, and rheology of fresh paste, with laser diffractometry, X-ray diffraction (XRD), and Raman imaging. A key contribution of the work is also the development of an automated Raman imaging algorithm that improves reproducibility by relying on objective criteria for Raman band and peak-top band selection.
Performance testing revealed substantial differences across the 12 PLCs. Early-age compressive strength varied between 2000 to 3800 psi at 1 day (mean: 3000 ± 465 psi), while calorimetry showed a range from 180 – 230 J/g in cumulative heat at 1 day (mean: 200 ± 18 J/g) and a 2.5 hour difference in set times. Rheological measurements also differed significantly, with dynamic yield stress varying between 16 to 59 Pa (mean: 34 ± 9.8 Pa) and the plastic viscosity of the stiffest cement being 0.61 Pa.s while that of the most compliant one was 0.12 Pa.s. Open porosity at 28 days ranged between 24% to 32% (mean: 28 ± 2.3%), and strong relationships were observed between porosity reduction and compressive strength (R2 = 0.75, RMSE = 12.7%). Bulk particle size analysis indicated wide variability in fineness, with D50 ranging from 9.8 – 12.3 m (mean: 11.2 ± 0.8 m) and a range of 2 – 4 m in D10 across cements (mean: 3 ± 0.7 m). The D10 showed the strongest correlation with early hydration heat at 1 day (R2 = 0.65, RMSE= 5.0%) and 3 days (R2 = 0.67, RMSE= 3.2%), confirming that ultrafine particles dominate early dissolution, nucleation, and reactivity. Chemical analysis using XRD showed large differences in clinker phase composition as well.
Raman imaging played a key role in linking chemistry and fineness at the phase level. The automated algorithm developed in this thesis produced Raman-based phase quantification that agreed closely with XRD, with a RMSE of 3.22% and most phase measurements within 5%. More importantly, Raman imaging enabled extraction of phase-specific PSDs revealed substantial differences in the fineness of individual phases that were masked in bulk PSD measurements. A composition coefficient (C_"c" ) that uses Raman phase composition and a phase-specific PSD factor (F_"psd" ) that represents the geometric mean of phase-D50 values were both correlated with hydration heat. When combined as the product (C_"combined" ), the predictive capability improved further, achieving the strongest correlation with 3 day cumulative heat (R2 = 0.71, RMSE= 3.0%).
These results show that performance variability in commercial Type IL cements arises from the combined effects of clinker phase composition and the fineness of reactive phases. By integrating laser diffractometry, XRD, and Raman imaging, this thesis provides a more complete framework for understanding PLC variability and offers quantitative tools for predicting hydration and strength. The automated Raman imaging approach developed here also advances the technique toward more routine use in industrial characterization and performance control.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-12-01The student, Yaman Garg, accepted the attached license on 2025-12-10 at 22:54.The student, Yaman Garg, submitted this Thesis for approval on 2025-12-10 at 23:05.This Thesis was approved for publication on 2025-12-11 at 08:18.DSpace SAF Submission Ingestion Package generated from Vireo submission #23115 on 2026-02-19 at 20:10:0
Sampling hurdles : “Borderline Illegitimate” to legitimate data.
No full textIn this paper the author discusses how sampling access and recruitment problems encountered in an in-depth interview study heightened her sensitivity to “borderline illegitimate” data. The term illegitimate data usually refers to the data collected during a covert study, whereas “legitimate” data are collected during an overt study. Hence, data collected during any nonconsented period(s) of an overt study lie on the borderline of illegitimacy and legitimacy, and constitute what the author calls borderline illegitimate data. Such data need legitimization before use. The borderline illegitimate data were collected during the pre- and postinterview stages of her study as they explained how medical and ethnic cultures and sensitivity to racism as a topic combined to create sample recruitment difficulties of the study. The author later legitimized them by sharing them with the participants, guaranteeing anonymity, and asking their permission to use them
Leggett–Garg inequalities for a quantum top affected by classical noise
No full textThe violation of the Leggett–Garg inequality is studied for a quantum top
(with angular momentum Jz of integer or half-integer size), being driven by classical
Gaussian white noise. The form of a longitudinal (Jz) or a transverse (Jx ) coupling
of noise to the angular momentum affects both (i) to what extent the Leggett–Garg
inequality is violated and (ii) how this violation is influenced by the size j of the
spinning top and direction of a coupling (transverse or longitudinal).We introduce j -
independent method, using two- dimensional invariant subspace of the system Hilbert
space, which allows us to find out strict analytical solution for a noise-free system
and with longitudinal coupling and to extract from the whole dynamics effects purely
induced by a noise. It is demonstrated that in the semi-classical limit of a large angular
momentum j and for the transverse coupling, the Leggett–Garg inequalities become
more strongly violated as compared to the deep quantum regime of small j
- …
