arXiv subjects

Myriam Nonaka

Publications and source records attributed to Myriam Nonaka.

9 recordsLinked to original sources

arXiv2026

Test of the essential collapse-locality loophole

Collapse-locality is an untested loophole in the violation of Bell's inequalities. The core of the argument is that the time value of photon detection is delayed by the time Tc required by the collapse of its quantum state. The value of Tc is given by the underlying theory of quantum collapse, and is mostly unknown. Depending on the value of Tc, detections in the performed Bell's experiments may have not been truly space-like separated events. This implies that the inequalities may have been violated as a consequence of (conspiratorial) information propagating at subluminal speed. We report an optical Bell experiment which closes the weaker ('essential') form of this loophole regardless the theory of quantum collapse. This is possible thanks to unique features of the setup. These features are: classical signals sent to the stations to define a time reference, and variable distance between the stations leaving all other parameters constant.

quant-ph↗

arXiv2025

Concentration Within Distribution: Unmasking Bitcoin's Structural Centralization Through Network Science

We construct the Bitcoin User Network (BUN) directly from raw blockchain data up to late 2025, which allows us to explore its mesoscopic properties and trace its temporal evolution. In particular, we analyze the structure of connected components and directed assortativity through the four variants of Newman's coefficient, implemented via custom algorithms and a dedicated database. Building on this, to characterize the distribution of structural influence, we introduce direction-sensitive centrality measures based on PageRank and HITS, which provide a complementary global analysis of the BUN and reveal a persistently unequal and increasingly core-periphery structure. In addition, we complement the structural analysis with a study of Bitcoin's price volatility using high-frequency market data. Overall, our results reveal a clear pattern of concentration within distribution: although the protocol is decentralized by design, the emergent user network evolves toward an asymmetric mesoscopic structure that indicates the existence of a few large-scale connected components that function as the critical backbone of the system.

cs.SI↗

arXiv2025

Experiment indicates that Realism, not Locality, is false in Quantum Mechanics

The interpretation of the meaning of Quantum Mechanics has faced controversy since its inception. Bell's inequalities are a touchstone in this controversy. Their observed violation demonstrates that at least one of the hypotheses involved in their derivation and test is false in Nature. In principle, one has to choose between accepting that Locality is false, what implies a possible contradiction with the Theory of Relativity, or accepting that Realism is false, what means to give up the existence of a physical world independent of the observer. The right answer has consequences both foundational and practical, and theoretical discussions have searched it for decades. We report the results of a Bell's experiment designed and performed to add observational information to the discussion. Three proposals to reveal the false hypothesis are carried out, namely: search of attractors in time series of observations, variation of randomness of binary series of outcomes between space-like and not-space-like separated conditions of observation, and test of a bound of Kolmogorov's complexity. The results are consistent with the absence of the specific form of Realism usually involved in the derivation of Bell's inequalities, while remaining compatible with Locality within the sensitivity of the tests. Independently of the foundational problem and of any interpretation, some bare observations have immediate practical impact on the best use of device-independent quantum Random Number Generators and Quantum Key Distribution.

quant-ph↗

arXiv2024

Proposal of an optical Bell's experiment to test the boundary between determinism and indeterminism in Quantum Mechanics

It was recently noted the existence of an apparently discontinuous boundary between determinism and indeterminism in Quantum Mechanics. We propose to explore this boundary in an optical Bell's experiment by recording the distribution, of the number of strings of outcomes of a given parity interrupted by outcomes of the other parity, as a function of their length. The features of these distributions for small rotations of the angle settings near critical points may indicate whether the underlying process is in-deterministic or not. Therefore, they may show that the boundary is discontinuous, or else, that determinism decays smoothly. The conditions the experimental setup must fulfill are discussed.

quant-ph↗

arXiv2024

Test of transient deviations from Quantum Mechanics in Bell's experiment

The conflict between Quantum Mechanics (QM) and Local Realism is most noticeable in the correlations observed between distant regions of a spatially spread entangled state. It has been hypothesized that transient deviations (from the values predicted by QM) may be observed if the correlations are measured in a time shorter than L/c, where L is the spatial spread of the entangled state and c is the speed of light. This hypothesis is appealing for it solves that conflict by minimally modifying the interpretation of QM, and opens the door to potentially fruitful nonlinear generalizations of QM without the risk of allowing faster-than-light signaling. The hypothesis is technically impossible to test directly nowadays, but a stroboscopic test is attainable. We present the results of such a test performed on a specially designed optical Bell setup with a distance between stations up to 24 m in straight line. No difference with the same observations performed at short distance, or evidence of transient deviations, is found. Yet, several hypotheses are involved in this experiment; they are detailed and briefly discussed. To say the least, the space left for the hypothesis of transient deviations is much reduced.

quant-ph↗

arXiv2024

Machine learning predicts extreme events in ultrashort pulse lasers

In this paper we present a nonlinear autoregressive neural network with a hidden layer of 50 neurons, three delays and one output layer that accurately is capable of predict the appearence of extreme events in a Kerr lens mode locking Ti:Sapphire laser with ultrashort pulses. Extreme events are produced in the context of a chaotic atractor and with chirped pulses. The prediction of this neural network works well with experimental and theoretical time series of amplitude of laser pulses. When fed with experimental time series we have 95.45\% of hits and 6.67\% of false positives while using theoretical time series the network predicts 100\% of extreme events but the false positive rise to 23.33\%.

physics.optics↗

arXiv2023

'Frequency-modulated' pulsed Bell setup avoids post-selection

Excepting event-ready setups, Bell experiments require post-selection of data to define coincidences. From the fundamental point of view, post-selection is a true 'logical loophole'. From the practical point of view, it implies a numerically heavy and time consuming task. In Quantum Key Distribution (QKD), it opens vulnerability in case of a hostile adversary. The core of the problem is to synchronize independent clocks during long observation runs. A pulsed source gets rid of clocks' drift, but there is still the problem of identifying the same pulse in each remote station. We use a frequency modulated pulsed source to achieve it. This immediately defines the condition of valid coincidences in a manner that is unaffected by the drift between the clocks. It allows finding the set of entangled pairs avoiding post-selection and in a way that is found to be optimal. It is also robust against a hostile adversary in the case of QKD.

quant-ph↗

arXiv2022

Testing randomness of series generated in Bell's experiment

The generation of series of random numbers is an important and difficult problem. Even the very definition of random is difficult. Appropriate measurements on entangled states have been proposed as the definitive solution to produce series of certified randomness. However, several reports indicate that quantum based devices show a disappointing rate of series rejected by standard tests of randomness. This problem is usually solved by using algorithms named extractors but, if the extractor were known by an eavesdropper (a situation that cannot be ruled out) the key security in QKD setups may be menaced. We use a toy fiber optic based setup, similar to a QKD one to be used in the field, to generate binary series, and evaluate their level of randomness according to Ville principle. Series are tested with a battery of standard statistical indicators, Hurst exponent, Kolmogorov complexity, minimum entropy, Takens dimension of embedding, and Augmented Dickey Fuller and Kwiatkowski Phillips Schmidt Shin to check stationarity. A theoretically predicted relationship between complexity and minimum entropy is observed. The good performance of a simple method to get useful series from rejected series, reported by Solis et al, is confirmed and supported with additional arguments. Regarding QKD, the level of randomness of series obtained by applying Toeplitz extractor to rejected series is found to be indistinguishable from the level of non-rejected raw ones.

quant-ph↗

arXiv2019

Randomness of imperfectly entangled states

The generation of series of random numbers is an important and difficult problem. Appropriate measurements on entangled states have been proposed as the definitive solution, based on the impossibility of exploiting quantum non locality to get faster than light signaling. There is a controversy regarding what is preferable to produce series with utilizable randomness in practice, high or low entanglement. We prepare biphotons with three different levels of entanglement, easy entangled, marginally entangled and no entangled. Randomness is evaluated, independently of the quantum non locality argument, through a battery of standard statistical tests, Hurst exponent, Kolmogorov complexity, Takens dimension of embedding, and Augmented Dickey Fuller and Kwiatkowski Phillips Schmidt Shin tests to check stationarity. The no entangled case is found to produce the smallest rate of not random series, and the marginal case the largest. Although the entangled case has a larger rate of not random series than the no entangled case, it is found still acceptable for QKD.

quant-ph↗