arXiv subjects

Fabrizio Tamburini

Publications and source records attributed to Fabrizio Tamburini.

At least 19 recordsLinked to original sources

arXiv2026

Design and Benchmarking of a Quantum Photonic Chip

We present the design and benchmarking of RP000, a quantum photonic processor capable of encoding a quantum system in the degrees of freedom of single photons, based on standard CMOS-compatible manufacturing processes, and working at room temperature. We benchmark it against machine learning tasks, evaluating three quantum-classical architectures of increasing complexity. Our experimental results and simulations show that RP000 achieves higher accuracy than classical networks of comparable size in multiple use cases. Compared to a superconducting quantum processor, RP000 exhibits superior noise tolerance. These findings demonstrate that RP000 can provide a scalable route toward efficient quantum applications.

quant-ph↗

arXiv2025

Random-projector quantum diagnostics of Ramsey numbers and a prime-factor heuristic for $R(5,5)=45$

We introduce a statistical framework for estimating Ramsey numbers by embedding two-color Ramsey instances into a $Z_2 \times Z_2$-graded Majorana algebra. This approach replaces brute-force enumeration with two randomized spectral diagnostics applied to operators of a given dimension d associated with Ramsey numbers: a linear projector $P_{lin}$ and an exponential map $P_{exp}(α)$, suitable for both classical and quantum computation. In the diagonal case, both diagnostics identify R(5,5) at n=45. The quantum realizations act on a reduced module and therefore require only five data qubits plus a few ancillas via block-encoding/qubitization for R(5,5)=45, in stark contrast to the $\binom{n}{2} \approx 10^3$ logical qubits demanded by direct edge encodings. We also provide few-qubit estimates for R(6,6) and R(7,7), and propose a simple "prime-sequence" consistency heuristic that connects R(5,5)=45 to constrained diagonal growth. Our method echoes Erdős's probabilistic paradigm, emphasizing randomized arguments rather than explicit colorings, and parallels the classical coin-flip approach to Ramsey bounds. Finally, we discuss potential applications of this framework to machine learning with a limited number of qubits.

quant-ph↗

arXiv2025

Charge constraint on M87* with twisted light

We propose a novel method to constrain the electric charge of the supermassive black hole M87* by analyzing the orbital angular momentum content of the light it emits. By leveraging the established analogy between rotating spacetimes and inhomogeneous optical media, we derive a simple analytical formula that relates the average orbital angular momentum in the observed radiation to the black hole's charge-to-mass ratio. Applying this relation to existing observational data, we place an upper bound of $\mathcal{Q}/M \lesssim 0.39$ on the charge of M87*. While the analysis focuses on electric charge, which is used here purely as a theoretical example since astrophysical black holes are expected to be approximately neutral, the method is general and can be extended to constrain other types of charges $\unicode{x2013}$ degrees of freedom that define distinct black hole solutions. These results demonstrate the potential of orbital angular momentum as a new fundamental degree of freedom to be exploited in astrophysics, providing a complementary and independent alternative to shadow-based techniques for probing the properties of rotating compact objects and testing gravity in the strong-field regime.

gr-qc↗

arXiv2025

Planckeons as mouths of quantum wormholes and holographic origin of spacetime

We argue that Planck-scale fluctuations ``planckeons'' realize a network of non-traversable Einstein--Rosen bridges and act as holographic devices. Modeling planckeons as wormhole mouths on extremal (RT) surfaces ties spacetime connectivity directly to entanglement. Using the Ryu--Takayanagi framework, we derive an entanglement entropy that governs the thermodynamics of the planckeon ensemble. The resulting partition function exhibits a high-temperature logarithmic entropy consistent with holographic scaling, while at low temperature the network freezes into a sparse remnant-like phase. A characteristic temperature $T_c$ (set by the planckeon gap) separates these regimes; in the noninteracting edge-mode description this marks a crossover (and becomes a genuine phase transition once interactions/pairing are included). Embedding a minimal length in the wormhole throat yields a quantum-corrected Bekenstein entropy in which the area term is supplemented by edge-mode contributions, thereby linking wormhole geometry with quantum-information flow and suggesting a holographic origin of spacetime and black-hole microstructure.

gr-qc↗

arXiv2025

ER = EPR in Loop Quantum Gravity: the Immirzi Parameter and the Continuum Limit

We recast the finite-region analysis of Einstein's equations that underpins the ER=EPR program into the loop quantum gravity (LQG) framework. By translating curvature-energy uncertainty relations into holonomy-flux kinematics, and by identifying Planckian Einstein-Rosen throats with single-puncture cuts through spin networks, we obtain a precise dictionary between entanglement and quantum geometry. Within this dictionary we derive the Barbero-Immirzi parameter directly from the entanglement/area increment of a minimal bridge, and show that a boundary edge-mode construction renders the Bekenstein - Hawking entropy coefficient universal and independent of $γ$ under a natural complex polarization. We further establish a refinement renormalization flow for spin-foam amplitudes driven by the finite-region curvature energy bound, which suppresses bubble divergences and yields a regulator-independent continuum limit under explicit conditions. Finally, we indicate observational consequences that follow from an $N$-party generalized uncertainty relation.

gr-qc↗

arXiv2025

A Majorana Relativistic Quantum Spectral Approach to the Riemann Hypothesis in (1+1)-Dimensional Rindler Spacetimes

Following the Hilbert-Pólya approach to the Riemann Hypothesis, we present an exact spectral realization of the nontrivial zeros of the Riemann zeta function $ζ(z)$ with a Mellin-Barnes integral that explicitly contains it. This integral defines the spectrum of the real-valued energy eigenvalues $E_n$ of a Majorana particle in a $(1+1)$-dimensional Rindler spacetime or equivalent Kaluza-Klein reductions of $(n+1)$-dimensional geometries. We show that the Hamiltonian $H_M$ describing the particle is hermitian and the spectrum of energy eigenvalues $\{E_n\}_{n \in \mathbb{N}}$ is countably infinite in number in a bijective correspondence with the imaginary part of the nontrivial zeros of $ζ(z)$ having the same cardinality as required by Hardy-Littlewood's theorem from number theory. The correspondence between the two spectra with the essential self-adjointness of $H_M$, confirmed with deficiency index analysis, boundary triplet theory and Krein's extension theorem, imply that all nontrivial zeros have real part $\Re ( z )=1/2$, i.e., lie on the ``critical line''. In the framework of noncommutative geometry, $H_M$ is interpreted as a Dirac operator $D$ in a spectral triple $(\mathcal{A}, \mathcal{H}, D)$, linking these results to Connes' program for the Riemann Hypothesis. The algebra $\mathcal{A}$ encodes the modular symmetries underlying the spectral realization of $ζ(z)$ in the Hilbert space $\mathcal{H}$ of Majorana wavefunctions, integrating concepts from quantum mechanics, general relativity, and number theory. This analysis offers a promising Hilbert-Pólya-inspired path to prove the Riemann Hypothesis.

math.GM↗

arXiv2025

Graded Paraparticle Algebra of Majorana Fields for Multidimensional Quantum Computing with Structured Light

We present a theoretical framework that integrates Majorana's infinite-component relativistic equation within the algebraic structure of paraparticles through the minimal nontrivial $\mathbb{Z}_2 \times \mathbb{Z}_2$--graded Lie algebras and $R$-matrix quantization. By mapping spin-dependent mass spectra to graded sectors associated with generalized quantum statistics, we derive an equation embodying Majorana's mass-spin relation describing Majorana quasiparticles of structured light carrying spin and orbital angular momentum. These quanta in the $\mathbb{Z}_2 \times \mathbb{Z}_2$--graded algebras and $R$-matrix formulations extend the previous results from superconducting qubits to photonic platforms and set up deterministic 2-photon gates involving at least two qubits encoded in a single photon without nonlinear effects. This makes feasible general quantum computing pathways exploiting fractional statistics through Nelson's quantum mechanics and implement a novel procedure for error correction in photonic platforms. Furthermore, this approach makes possible to set paraparticle-based quantum information processing, beyond fermions and bosons, using graded qudits.

quant-ph↗

arXiv2024

Quantum collapse as undecidable proposition in an Everettian multiverse

Our representation of the Universe is built with sequences of symbols, numbers, operators, rules and undecidable propositions defining our mathematical truths, represented either by classical, quantum and probabilistic Turing Machines containing intrinsic randomness. Each representation is at all effects a physical subset of the Universe, a metastructure of events in space and time, which actively participate to the evolution of the Universe as we are internal observers. The evolution is a deterministic sequence of local events, quantum measurements, originated from the local wavefunction collapse of the complementary set of the observers that generate the local events in the Universe. With these assumptions, the Universe and its evolution are described in terms of a semantically closed structure without a global object-environment loss of decoherence as a von Neumann's universal constructor with a semantical abstract whose structure cannot be decided deterministically a-priori from an internal observer. In a semantically closed structure the realization of a specific event writing the semantical abstract of the constructor is a problem that finds a "which way" for the evolution of the Universe in terms of a choice of the constructor's state in a metastructure, the many-world Everett scenario from the specific result of a quantum measurement, a classical Gödel undecidable proposition for an internal observer, exposing the limits of our description and possible simulation of the Universe.

quant-ph↗

arXiv2023

Ultrafast modulations in stellar, solar and galactic spectra: Dark Matter and numerical ghosts, stellar flares and SETI

From new results presented in the literature we discuss the hypothesis that the ultrafast periodic spectral modulations at $f_S \simeq 0.607$ THz found in the spectra of $236$ stars of the Sloan Digital Sky Survey (SDSS) [1] were due to oscillations induced by dark matter (DM) cores in their centers [2] behaving as oscillating boson stars [3,4]. Two additional frequencies in the redshift-corrected SDSS galactic spectra were found [5], $ f_{1,G} \simeq 9.5$ THz, the beating between $f_S$ and a spurious frequency, $f_{2,G} \simeq 8.9$ THz, introduced during the data analysis [6]. The indication that $f_S$ can be real is its detection in a real solar spectrum but not in the Kurucz's artificial solar spectrum [6,7,8]. Then, independent SETI observations of four of these stars could not confirm with high confidence, but not completely exclude, the presence of $f_S$ in their power spectra [9] while the radio SETI deep-learning analysis with artificial intelligence confirmed indirectly $f_S$ detecting a narrowband Doppler drifting of radio signals in two of these stars over a sample of $7$ with a high S/N [10]. Numerical simulations suggest that the drifting can be due to frequency and phase modulation in time of the observed frequencies at $1.3-1.7$ GHz with $f_S$. This would imply a DM upper mass limit $m_a \lesssim 2.4 \times 10^{3}~ \mathrm{μeV}$ [2] which also agrees with the results from the gamma ray burst GRB221009A [11,12,13], laser interferometry [14], suggesting new physics for the muon g-2 anomaly [15].

astro-ph.GA↗

arXiv2022

Constraining the Generalized Uncertainty Principle with the light twisted by rotating black holes and M87*

We test the validity of the Generalized Heisenberg's Uncertainty principle in the presence of strong gravitational fields nearby rotating black holes; Heisenberg's principle is supposed to require additional correction terms when gravity is taken into account, leading to a more general formulation also known as the Generalized Uncertainty Principle. Using as probe electromagnetic waves acquiring orbital angular momentum when lensed by a rotating black hole, we find from numerical simulations a relationship between the spectrum of the orbital angular momentum of light and the corrections needed to formulate the Generalized Uncertainty Principle, here characterized by the rescaled parameter $β_0$, a function of the Planck's mass and the bare mass of the black hole. Then, from the analysis of the observed twisted light due to the gravitational field of the compact object observed in M87*, we find new limits for the parameter $β_0$. With this method, complementary to black hole shadow circularity analyses, we obtain more precise limits from the experimental data of M87*, confirming the validity of scenarios compatible with General Relativity, within the uncertainties due to the experimental errors present in EHT data and those due to the numerical simulations and analysis.

gr-qc↗

arXiv2021

Majorana quanta, string scattering, curved spacetimes and the Riemann Hypothesis

The Riemann Hypothesis states that the Riemann zeta function $ζ(z)$ admits a set of ``non-trivial'' zeros that are complex numbers supposed to have real part $1/2$. Their distribution on the complex plane is thought to be the key to determine the number of prime numbers before a given number. Hilbert and Pólya suggested that the Riemann Hypothesis could be solved through the mathematical tools of physics, finding a suitable Hermitian or unitary operator that describe classical or quantum systems, whose eigenvalues distribute like the zeros of $ζ(z)$. A different approach is that of finding a correspondence between the distribution of the $ζ(z)$ zeros and the poles of the scattering matrix $S$ of a physical system. Our contribution is articulated in two parts: in the first we apply the infinite-components Majorana equation in a Rindler spacetime and compare the results with those obtained with a Dirac particle following the Hilbert-Pólya approach showing that the Majorana solution has a behavior similar to that of massless Dirac particles and finding a relationship between the zeros of zeta end the energy states. Then, we focus on the $S$-matrix approach describing the bosonic open string scattering for tachyonic states with the Majorana equation. Here we find that, thanks to the relationship between the angular momentum and energy/mass eigenvalues of the Majorana solution, one can explain the still unclear point for which the poles and zeros of the $S$-matrix of an ideal system that can satisfy the Riemann Hypothesis, exist always in pairs and are related via complex conjugation. As claimed in the literature, if this occurs and the claim is correct, then the Riemann Hypothesis could be in principle satisfied, tracing a route to a proof.

gr-qc↗

arXiv2021

Twisted light, a new tool for General Relativity and beyond

We describe and present the first observational evidence that light propagating near a rotating black hole is twisted in phase and carries orbital angular momentum. The novel use of this physical observable as an additional tool for the previously known techniques of gravitational lensing allows us to directly measure, for the first time, the spin parameter of a black hole. With the additional information encoded in the orbital angular momentum, not only can we reveal the actual rotation of the compact object, but we can also use rotating black holes as probes to test General Relativity.

gr-qc↗

arXiv2021

Majorana Tower and Cellular Automaton Interpretation of Quantum Mechanics down to Planck Scales

A deterministic reformulation of quantum mechanics can bypass the usual philosophical interpretations of probability and stochasticity that are found in the literature. This can be obtained with the ontological formulation of quantum mechanics, obtained by writing the Hamiltonian of a quantum system in a way to render it mathematically equivalent to a deterministic system. Such deterministic models are thought to consist of elementary cells - cellular automata - inside which the quantities describing the dynamics oscillate in periodic orbits, extending and replacing the quantum-mechanical classical language based on harmonic oscillators. Here we show that the structure of the cellular automata sets find a clear physical interpretation with the infinite-components equation published by Majorana in 1932, also known as the Majorana Tower: the cellular automata are elementary building blocks generated by the Poincaré group of spacetime transformations with positive-defined energy down to the elementary building blocks of the fabric of spacetime. Interestingly, the mathematical approach here considered presents close relationships with those used for the distribution of prime numbers in the Pólya-Hilbert conjecture for the Riemann Hypothesis.

physics.gen-ph↗

arXiv2021

Testing the equivalence principle and discreteness of spacetime through the $t^3$ gravitational phase with quantum information technology

We propose a new thought experiment, based on present-day Quantum Information Technologies, to measure quantum gravitational effects through the Bose-Marletto-Vedral (BMV) effect by revealing the gravitational $t^3$ phase term, its expected relationships with low-energy quantum gravity phenomena and test the equivalence principle of general relativity. The technique here proposed promise to reveal gravitational field fluctuations from the analysis of the stochastic noise associated to an ideal output of a measurement process of a quantum system. To improve the sensitivity we propose to cumulate the effects of the gravitational field fluctuations in time on the outputs of a series of independent measurements acted on entangled states of particles, like in the building of a quantum cryptographic key, and extract from the associated time series the effect of the expected gravitational field fluctuations. In fact, an ideal quantum cryptographic key, built with the sharing of maximally entangled states of particles, is represented by a random sequence of uncorrelated symbols mathematically described by a perfect white noise, a stochastic process with zero mean and without correlation between its values taken at different times. Gravitational field perturbations, including quantum gravity fluctuations and gravitational waves, introduce additional phase terms that decohere the entangled pairs used to build the quantum cryptographic key, with the result of coloring the white noise. We find that this setup, built with massive mesoscopic particles, can potentially reveal the $t^3$ gravitational phase term and thus, the BMV effect.

gr-qc↗

arXiv2021

Stability tests in time of OAM multiplexing schemes in highly disturbed environments

We report the results of tests of data transmission and signal stability in time of two different wide-band multiplexing (MUX) schemes, each in a point-to-point configuration, based on electromagnetic waves carrying Orbital Angular Momentum (OAM) in noisy real-world settings. Each radio link transmitted two high definition wide--band analog TV channels in the same frequency band with FM-carrier centered at $2.414$ GHz and $27$ MHz bandwidth, encoded with different OAM modes in the same polarization state, uninterruptedly for $5$ months during the world exhibition ``Globale--Digitale'' at ZKM in Karlsruhe and in other $2$ months time slots taken in the following $4$ years, $24$ hours per day. We show the practical feasibility of the use of stable OAM radio/TV links in the real world for a long time, paving the way for for secure and efficient communication schemes also under electromagnetic jamming conditions.

physics.app-ph↗

arXiv2021

Kerr spacetime geometric optics for vortex beams

We apply the analogy between gravitational fields and optical media in the general relativistic geometric optics framework to describe how light can acquire orbital angular momentum (OAM) when it traverses the gravitational field of a massive rotating compact object and the interplay between OAM and polarization. Kerr spacetimes are known not only to impose a gravitational Faraday rotation on the polarization of a light beam, but also to set a characteristic fingerprint in the orbital angular momentum distribution of the radiation passing nearby a rotating black hole (BH). Kerr spacetime behaves like an inhomogeneous and anisotropic medium, in which light can acquire orbital angular momentum and spin-to-orbital angular momentum conversion can occur, acting as a polarization and phase changing medium for the gravitationally lensed light, as confirmed by the data analysis of M87* black hole.

gr-qc↗

arXiv2020

Geostationary Real-Time 3D Polarimetric RADAR Imaging by Orbital Angular Momentum Interferometry and Multi-Chromatic Analysis

We design the proof of concept for high-resolution (HR) real-time (RT), Geosynchronous and Geostationary (Geo) Polarimetric (Pol) using orbital angular momentum (OAM) interferometry - radio detection and ranging (RADAR) (HR-RT-GeoPolInt-OAM-RADAR) and multi-chromatic analysis (MCA) extended to Tomography (HR-RT-GeoPolInt-OAM-MCA-TomoRADAR). The OAM interferometry communication channel is generated by two fixed sources distanced by a given spatial baseline and used for range-azimuth synthesis. The frequency channel, instead, is used to provide information about the altitude. Finally, the information encoded in the polarization of the electromagnetic (EM) waves, which is related to the Spin Angular Momentum (SAM), is used to synthesize full-Pol RADAR images, with technological redundancy. Here we present the design of a planar vortex antenna, tailored for Geo applications, where the imaging system transmits ''ad-hoc`` structured wave packets using an incremental stepped chirp strategy and with single-mode OAM linearly incremented modulation. We assign the resolutions of each dimension to three bands assumed by the EM wave. The radial and tangential components received from the HR-RT-GeoPolInt-OAM communication channel backscattered signals are used to focus, through fast-Fourier transform (FFT) techniques, a range-azimuth image that belongs to a single epoch at a given constant frequency. Each OAM fast-time RADAR image is separated in frequency by using MCA. This procedure is repeated for all the epochs of the entire stepped-frequency chirp. Once each two-dimensional image is synthesized, they are co-registered, and the HR-RT-GeoPolInt-OAM-MCA-TomoRADAR slices are focused in altitude by using FFT techniques. Range-azimuth and tomographic resolutions depend on the OAM value and the stepped frequency chirp bandwidths.

eess.SP↗

arXiv2020

CPT Symmetry in Projective de Sitter Universes

In a recent work, Boyle, Finn and Turok hypothesized a model of universe that does not violate the CPT-symmetry as alternative for inflation. With this approach they described the birth of the Universe from a pair of universes, one the CPT image of the other, living in pre- and post-big bang epochs. The CPT-invariance strictly constrains the vacuum states of the quantized fields, with notable consequences on the cosmological scenarios. Here we examine the validity of this proposal by adopting the point of view of archaic cosmology, based on de Sitter projective relativity, with an event-based reading of quantum mechanics, which is a consequence of the relationship between the universal information reservoir of the archaic universe and its out-of-equilibrium state through quantum jumps. In this scenario, the big bang is caused by the instability of the original (pre)vacuum with respect to the nucleation of micro-events that represent the actual creation of particles. Finally, we compare our results with those by Turok et al., including the analytic continuation across the big bang investigated by Volovik and show that many aspects of these cosmological scenarios find a clear physical interpretation by using our approach. Moreover, in the archaic universe framework we do not have to assume a priori the CPT-invariance like in the other models of universe, it is instead a necessary consequence of the archaic vacuum structure and the nucleation process, divided into two specular universes.

gr-qc↗