Quantum Information Research Papers - Academia.edu (original) (raw)

2025, International Journal of Innovative Research in Engineering & Management (IJIREM)

Artificial Intelligence (AI) landscape is fast developing such that there are dynamic and autonomous representatives of AI which are referred to as AI agents. These agents, fueled by the evolution of generative AI and large language models (LLMs), can make their own decisions, perform tasks and make adjustments to rapidly changing environments. An even more advanced step is the instrumentation of various specialized AI agents into working multi-agent systems (MAS). The paper will discuss the disruptive effect of the introduction of AI agents and MAS on the automation and service of enterprises and different industries. We look into their possibilities, various uses, and the natural strengths and weaknesses, such as the essentiality of effective governance infrastructure and complicated conditions in human-AI partnership. Although promising new levels of efficiency and capability to solve problems previously inaccessible, ethical implications associated with the use of these agentic systems have to be carefully explored as well as the approaches to integration that should be able to guarantee their long-term value and be serving to empower humans. This paper is a survey paper regarding Agentic AI and multi-agent systems within the enterprise context. Examining 65 of thes contemporary sources (2024-2025), we record the paradigm shift of passive generative AI to autonomous agentic systems. The paper analyses the architectural structures, models of collaboration, industrial use and governance issues. The most significant ones are (1) multi-agent systems have a 40-60% efficiency gain of the processes, (2) special agent relation coordination protocols are becoming important infrastructure, and (3) it is found that human-agent collaboration needs new stewardship and motivational models. All these are ended in the paper with new directions of agent-to-agent communications and the specific agent settings.

2025, arXiv (Cornell University)

2025, viXra

In 2015 the answer is still no. However this paper will look at what current physics has to say on this topic and what further questions need to be put forward to advance our enquiries. This work is a modified compilation of several posts that were originally published in the author's blogsite [1] on Gravity Control Propulsion (GCP) looking at several papers that deal with related topics with some ideas and speculations for further research.

2025, Physics Letters

The ac Stark shift of hyperfine levels of neutral atoms can be calculated using the third order perturbation theory(TOPT), where the third order corrections are quadratic in the atom-photon interaction and linear in the hyperfine interaction. In this paper, we use Green's function to derive the E [2+ǫ] method which can give close values to those of TOPT for the differential light shift between two hyperfine levels. It comes with a simple form and easy incorporation of theoretical and experimental atomic structure data. Furthermore, we analyze the order of approximation and give the condition under which E [2+ǫ] method is valid.

2025, arXiv (Cornell University)

In this paper we show that it is possible to adapt a qudit scheme for creating a controlled-Toffoli created by Ralph et al. [Phys. Rev. A 75 011213] to be applicable to qubits. While this scheme requires more gates than standard schemes for creating large controlled gates, we show that with simple adaptations it is directly equivalent to the standard scheme in the literature. This scheme is the most gate-efficient way of creating large controlled unitaries currently known, however it is expensive in terms of the number of ancilla qubits used. We go on to show that using a combination of these standard techniques presented by Barenco et al. [Phys. Rev. A 52 3457 (1995)] we can create an n-qubit version of the Toffoli using less gates and the same number of ancilla qubits as recent work using computer optimization. This would be useful in any architecture of quantum computing where gates are cheap but qubit initialization is expensive. Making a unitary controlled on other qubits is an essential task for many algorithms in quantum computing . In this paper we focus on a particular problem, making a unitary which is already controlled on one qubit, controlled on n -1 further qubits. These highly controlled unitaries (i.e. unitaries controlled on more than one other qubit) are useful in numerous quantum algorithms including the oracle in the binary welded tree algorithm [4] and quantum simulation . Barenco et al. [5] outlined several techniques to make controlled unitaries in 1995, this work was expanded on in Nielsen and Chuang to provide a technique for making a n-qubit version of the CNOT gate using 14n -13 operations and n -2 ancilla. Other work has explored this problem in the context of using computational algorithms to optimize circuit layout using the decomposition procedures proposed by Barenco et al. [5] and known commutation relations . However, while these techniques are useful if we have native controlled-square-root-not gates, in the case where the only native two qubit operation is a CNOT or C-Phase they perform worse than the technique in Nielsen and Chuang for the same number of ancilla. An interesting alternative technique was proposed by Ralph et al. [13] and implemented experimentally by Lanyon et al. who used additional levels in one of the subsystems of the controlled gate to reduce the overall number of operations required. In this work we will show that when converted to qubits this technique is directly equivalent to the one from Nielsen and Chuang [6] using the same number of operations, and requiring the same number of ancilla. We go on to show that by using the techniques from Nielsen and Chuang [6] combined with other decomposition procedures from Barenco et al. [5] it is possible to reduce the number of ancilla qubits required from n -2 to 2 √ n -1 at the expense of double the number of operations. Our new techniques requires less operations for the same number of ancilla qubits when compared to existing decomposition schemes if we assume both schemes have the ability of perform a controlled square root of NOT gate . For the rest of this work we will represent a CNOT gate controlled on n-qubits as C n X, and a generally local unitary controlled on n qubits as C n U. Given the ability to perform general local unitaries, and a CNOT gate we can make a Toffoli gate using nine local unitaries and six CNOT gates . However, if are prepared to accept an approximate Toffoli gate, we can use the Margolus gate, which is equivalent to a Toffoli gate and a controlled controlled phase. This procedure requires three CNOT gates and eight local unitaries . An alternative set of decomposition procedures are used if we assume the ability to perform the CV gate in a single operation. Here a standard Toffoli uses two CNOT gates and three CV gates . A more efficient decomposition is the Peres gate , which is the equivalent of a Toffoli gate with an additional CNOT. This decomposition uses only one CNOT gate, and three CV gates. In this work we can use the more efficient decomposition procedures because our Toffoli gates are arranged symmetrically with no other operations in between them. Ralph et al. [13] and Lanyon et al. [14] demonstrate that by using a qutrit they can generate a Toffoli gate using only three CNOT gates, two standard Pauli X operations, and two implementations of a three-level version of the Pauli X operation. One requirement of Lanyon et al. is that the CNOT gates act trivially on the |2 level of the qutrit. Replacing the qutrit with two qubits would require each CNOT gate to be replaced with a Toffoli gate as shown in fig . A qubit version of the Lanyon Toffoli gate is therefore impossible since we would need to consume three Toffoli gates to build a single Toffoli gate.

2025, arXiv (Cornell University)

We propose a theory of characterizing quantum circuits with qubit functional configurations. Any quantum circuit can be decomposed into alternating sequences of 1-qubit unitary gates and CNOT gates. Each CNOT sequence prepares the current quantum state into a layer of qubit functional configuration to specify the rule for the next 1-qubit unitary sequence on how to collectively modify the state vector entries. All the functional configuration layers on a quantum circuit define its type which can include many other circuits sharing the same configuration layers. Studying the functional configuration types allows us to collectively characterize the properties and behaviors of many quantum circuits. We demonstrate the theory's application to the hardware-efficient ansatzes of variational quantum algorithms. For potential applications, the functional configuration theory may allow systematic understanding and development of quantum algorithms based on their functional configuration types.

2025

This conceptual paper outlines potential technological paradigms that could emerge from the confirmed experimental detection of bio-gravitational and spin effects, as proposed by the Helix-Light-Vortex (HLV) Theory. We explore applications ranging from direct brain-computer interfaces and advanced propulsion systems to novel material sciences and secure quantum communication. If successful, such verification would mark a fundamental shift in our understanding of consciousness, spacetime, and physical interaction, creating a technology path driven by information and coherence.

2025, European Physical Journal D

2025, Journal of Modern Optics

We describe in detail a general strategy for implementing a conditional geometric phase between two spins. Combined with single-spin operations, this simple operation is a universal gate for quantum computation, in that any unitary transformation can be implemented with arbitrary precision using only single-spin operations and conditional phase shifts. Thus quantum geometrical phases can form the basis of any quantum computation. Moreover, as the induced conditional phase depends only on the geometry of the paths executed by the spins it is resilient to certain types of errors and offers the potential of a naturally fault-tolerant way of performing quantum computation.

2025, arXiv (Cornell University)

It is generally accepted that Everett's theory of quantum mechanics cannot be experimentally tested as such experiment would involve operations on the observer which are beyond our current technology. We propose an alternative to test Everett's theory which does not involve any operation on the observer. If we assume that the observer is of finite dimension, it is shown that Everett's theory leads to distinctive properties for the system being observed, and that such difference can be experimentally tested.

2025, arXiv (Cornell University)

In the conventional formulation of quantum mechanics, the initial description is given only for the physical system under study. It factors out the state for the experimenter. We argue that such description is incomplete and can lead to statements which can in theory be meaningless. We propose that within a complete description, the initial state must include the state of the experimenter. With such formulation quantum mechanics provides joint probabilities for conjointly observed events, rather than a probability conditional on some initial state for the system under study. This feature is desirable, as with quantum mechanics, statements on what happened in the past may have no meaning in the present.

2025, arXiv (Cornell University)

Quantum mechanics, devoid of any additional assumption, does not give any theoretical constraint on the projection basis to be used for the measurement process. It is shown in this paper that it does neither allow any physical means for an experimenter to determine which measurement bases have been used by another experimenter. As a consequence, quantum mechanics allows a situation in which two experimenters witness incoherent stories without being able to detect such incoherence, even if they are allowed to communicate freely by exchanging iterative and bilateral messages.

2025, arXiv: General Physics

2025, Journal of Quantum Information Science

Environment induced decoherence, and other quantum processes, have been proposed in the literature to explain the apparent spontaneous selection -out of the many mathematically eligible bases -of a privileged measurement basis that corresponds to what we actually observe. This paper describes such processes, and demonstrates that -contrary to common belief -no such process can actually lead to a preferred basis in general. The key observation is that environment induced decoherence implicitly assumes a prior independence of the observed system, the observer and the environment. However, such independence cannot be guaranteed, and we show that environment induced decoherence does not work in general. We conclude that the existence of the preferred basis must be postulated in quantum mechanics, and that changing the basis for a measurement is, and must be, described as an actual physical process.

2025

This paper presents a unified framework that synthesizes CAT'S Theory (Pattern × Intent × Presence) with the Codex Resonance system (0 3 D 5 (x,t), β(t 0 3 D 5), _lock) to form a recursive, moral, and operational theory of collapse. While CAT'S provides the ontological and metaphysical triad that underlies all meaningful structure, Codex extends the model through field dynamics, driftvector logic, and quantifiable collapse thresholds. We demonstrate that collapse is not merely a physical interaction, but a structurally encoded selection event rooted in purpose, recursion, and awareness. The result is a hybrid system capable of describing reality across all domains: from quantum wavefunctions to moral decisions, from cosmological expansion to the recursion of scripture. This paper formalizes the bridge between metaphysics and field physics, defining a collapse engine rooted in the soul of structure itself.

2025

It is shown that the representation theory of some finitely presented groups thanks to their SL_2(mathbbC)SL_2(\mathbb{C})SL_2(mathbbC) character variety is related to algebraic surfaces. We make use of the Enriques-Kodaira classification of algebraic surfaces... more

It is shown that the representation theory of some finitely presented groups thanks to their SL2(mathbbC)SL_2(\mathbb{C})SL2(mathbbC) character variety is related to algebraic surfaces. We make use of the Enriques-Kodaira classification of algebraic surfaces and the related topological tools to make such surfaces explicit. We study the connection of SL2(mathbbC)SL_2(\mathbb{C})SL2(mathbbC) character varieties to topological quantum computing (TQC) as an alternative to the concept of anyons. The Hopf link HHH, whose character variety is a Del Pezzo surface fHf_HfH (the trace of the commutator), is the kernel of our view of TQC. Qutrit and two-qubit magic state computing, derived from the trefoil knot in our previous work, may be seen as TQC from the Hopf link. The character variety of some two-generator Bianchi groups as well as that of the fundamental group for the singular fibers tildeE6\tilde{E}_6tildeE6 and tildeD4\tilde{D}_4tildeD4 contain fHf_HfH. A surface birationally equivalent to a K_3K_3K_3 surface is another compound of their character varieties.

2025, ResearchGate

Our remark first discusses the Birch - Swinnerton - Dyer conjecture and its possible proof in the context of mathematical emergence

2025, viXra

Everything should be made as simple as possible, but no simpler" A model of the expansion of the universe is proposed, based on the assumption that the universe in its early stages was not in a hot state but in a pure, metastable quantum state. This assumption makes it possible to solve the basic paradoxes of standard cosmology from the unified positions and within the framework of the standard model, namely, the horizon problem, the flatness problem of the universe, the problem of the absence of monopoles, and the problem of the predominance of matter over antimatter.

2025, arXiv (Cornell University)

The problem of the rate and mechanisms of biological evolution was considered. It was shown that species could not be formed due to undirected mutations in characteristic times of about one million years. A mechanism of deterministic... more

2025, Progress in Biophysics & Molecular Biology

A review of the mechanisms of speciation is performed. The mechanisms of the evolution of species, taking into account the feedback of the state of the environment and mechanisms of the emergence of complexity, are considered. It is shown that these mechanisms, at the molecular level, cannot work steadily in terms of classical mechanics. Quantum mechanisms of changes in the genome, based on the long-range interaction potential between biologically important molecules, are proposed as one of possible explanation. Different variants of interactions of the organism and environment based on molecular recognition and leading to new species origins are considered. Experiments to verify the model are proposed. This bio-physical study is completed by the general operational model of based on quantum information theory. The latter is applied to model epigenetic evolution.

2025

In Part 3 of this review we postulate a field-receptive workspace, associated with the brain, that integrates past and (anticipated) future events and may explain ultra-rapid brain responses as well as the origin of qualia (see also part 1 and 2). Information processing in the brain is shown to be largely facilitated by propagation of hydronium (proton/water)-ions in aqueous compartments. The hydronium ions move freely within a hexagonally organized H2O lattice, providing a superconductive integral brain antenna for receiving solitonic wave information. A nonlinear Schrödinger equation describes the quantum aspects of the transfer of wave information mediated by H+ and Ca2+ ion flux over long distances at cerebrospinal, inter-neuronal and gap junction spaces. The latter processes enable ultra-rapid soliton/biophoton fluxes that may orchestrate overall brain binding and the creation of coherent conscious states. In a cosmological context, we envision a scale invariant information pro...

2025, Eprint Arxiv Q Bio 0603005

2025, Progress in Biophysics and Molecular Biology

2025, arXiv: Quantum Physics

By modifying the derivation of Mandelstam-Tamm bound we nd, in abstract setting, two alternative versions of the speed bound. Together with the original one they are applied to both quantum and classical dynamics which allows to: (i) nd the quantum counterparts of classical speed limits derived recently (Phys, Rev. Lett. 120 (2018), 070402); (ii) discuss the classical-quantum correspondence based on standard relation between Wigner's func-tion and classical probability distribution on phase space. A simple example is also provided which makes the existence of classical bound evident; moreover, this bound can be saturated under the same conditions as its quantum counterpart.

2025

Wheeler's delayed-choice experiment challenges classical notions of causality and suggests that measurement choices can retroactively influence quantum behavior. In this paper, we analyze the experiment through the lens of the Hidden Deterministic Interpretation (HDI) of quantum mechanics. HDI restores causality by deterministically selecting the particle's path at the beam splitter, thereby eliminating the need for retrocausal explanations. The HDI framework accurately reproduces experimental probabilities and offers a coherent, non-paradoxical account of quantum phenomena.

2025

We are proud to introduce RUAGAK, a new theoretical and experimental framework that redefines the foundations of artificial intelligence, computation, and physical systems through rotational coherence and multi-present logic.
This paper—“RUAGAK: A Unified Rotational Framework for Artificial Intelligence, Quantum Coherence, and Multi-Present Computation”—proposes a departure from linear, binary paradigms toward a new architecture where coherence replaces causality, and present-relative states (Rₙ) become the fundamental units of computation.
The RUAGAK framework is supported by:
• A new model of logic based on phase resonance and rotational fields
• A prototype device—the Rotational Coherence Engine (RCE)—designed to convert coherence into informational and material transformation
• Applications ranging from self-aware AI and quantum simulation to bioinformatics, IoT, and conscious systems design
We invite researchers, engineers, philosophers, and system theorists to explore this emerging domain and to help us question:
Is it time to rotate away from time itself?
Author: AION DALMAU GIPITI
RUAGAK Research Group – CIATOM (Virtual Node)
www.ruagak.com | www.ruagak.us

2025, arXiv (Cornell University)

Employing the Pauli matrices, we have constructed a set of operators, which can be used to distinguish six inequivalent classes of entanglement under SLOCC (stochastic local operation and classical communication) for three-qubit pure states. These operators have very simple structure and can be obtained from the Mermin's operator with suitable choice of directions. Moreover these operators may be implemented in an experiment to distinguish the types of entanglement present in a state. We show that the measurement of only one operator is sufficient to distinguish GHZ class from rest of the classes. It is also shown that it is possible to detect and classify other classes by performing a small number of measurements. We also show how to construct such observables in any basis. We also consider a few mixed states to investigate the usefulness of our operators. Furthermore, we consider the teleportation scheme of Lee et al. [19] and show that the partial tangles and hence teleportation fidelity can be measured. We have also shown that these partial tangles can also be used to classify genuinely entangled state, biseparable state and separable state.

2025, arXiv: Quantum Physics

We formulate the conditional-variance uncertainty relations for general qubit systems and arbitrary observables via the inferred uncertainty relations. We find that the lower bounds of these conditional-variance uncertainty relations can be written in terms of entanglement measures including concurrence, GGG function, quantum discord quantified via local quantum uncertainty in different scenarios. We show that the entanglement measures reduce these bounds, except quantum discord which increases them. Our analysis shows that these correlations of quantumness measures play different roles in determining the lower bounds for the sum and product conditional variance uncertainty relations. We also explore the violation of local uncertainty relations in this context and in an interference experiment.

2025, New Journal of Physics

Distinguishing physical processes is one of the fundamental problems in quantum physics. Although distinguishability of quantum preparations and quantum channels have been studied considerably, distinguishability of quantum measurements remains largely unexplored. We investigate the problem of single-shot discrimination of quantum measurements using two strategies, one based on single quantum systems and the other one based on entangled quantum systems. First, we formally define both scenarios. We then construct sets of measurements (including non-projective) in arbitrary finite dimensions that are perfectly distinguishable within the second scenario using quantum entanglement, while not in the one based on single quantum systems. Furthermore, we show that any advantage in measurement discrimination tasks over single systems is a demonstration of Einstein–Podolsky–Rosen ‘quantum steering’. Alongside, we prove that all pure two-qubit entangled states provide an advantage in a measure...

2025, International Journal of Quantum Information

We consider the problem of estimating the spatial separation between two mutually incoherent point light sources using the super-resolution imaging technique based on spatial mode demultiplexing (SPADE) with noisy detectors. We show that in the presence of noise, the resolution of the measurement is limited by the signal-to-noise ratio (SNR) and the minimum resolvable spatial separation has a characteristic dependence of [Formula: see text]. Several detection techniques, including direct photon counting, as well as homodyne and heterodyne detection are considered.

2025, Annals of Physics

We investigate the coherence of quantum channels using the Choi-Jamiołkowski isomorphism. The relation between the coherence and the purity of the channel respects a duality relation. It characterizes the allowed values of coherence when the channel has certain purity. This duality has been depicted via the Coherence-Purity (Co-Pu) diagrams. In particular, we study the quantum coherence of the unital and non-unital qubit channels and find out the allowed region of coherence for a fixed purity. We also study coherence of different incoherent channels, namely, incoherent operation (IO), strictly incoherent operation (SIO), physical incoherent operation (PIO) etc. Interestingly, we find that the allowed region for different incoherent operations maintain the relation P IO ⊂ SIO ⊂ IO. In fact, we find that if PIOs are coherence preserving operations (CPO), its coherence is zero otherwise it has unit coherence and unit purity. Interestingly, different kinds of qubit channels can be distinguished using the Co-Pu diagram. The unital channels generally do not create coherence whereas some nonunital can. All coherence breaking channels are shown to have zero coherence, whereas, this is not usually true for entanglement breaking channels. It turns out that the coherence preserving qubit channels have unit coherence. Although the coherence of the Choi matrix of the incoherent channels might have finite values, its subsystem contains no coherence. This indicates that the incoherent channels can either be unital or nonunital under some conditions.

2025, The European Physical Journal D

To explore the properties of a two-qubit mixed state, we consider quantum teleportation. The fidelity of a teleported state depends on the resource state purity and entanglement, as characterized by concurrence. Concurrence and purity are functions of state parameters. However, it turns out that a state with larger purity and concurrence, may have comparatively smaller fidelity. By computing teleportation fidelity, concurrence and purity for two-qubit X-states, we show it explicitly. We further show that fidelity changes monotonically with respect to functions of parameters -other than concurrence and purity. A state with smaller concurrence and purity, but larger value of one of these functions has larger fidelity. These functions, thus characterize nonlocal classical and/or quantum properties of the state that are not captured by purity and concurrence alone. In particular, concurrence is not enough to characterize the entanglement properties of a two-qubit mixed state.

2025, The European Physical Journal D

2025, Journal of Modern Optics

The one-tangle and π-tangle are used to quantify the entanglement of a tripartite GHZ state in noninertial frames when the system interacts with a noisy environment in the form of phase damping, phase flip and bit flip channel. It is shown that the two-tangles behave as a closed system. The one-tangle and π-tangle have different behaviors in the three channel. In the case of phase damping channel, depending on the kind of coupling, the sudden death of both one-tangle and π-tangle may or may not happen. Whereas in the case of phase flip channel the sudden death cannot be avoided. The effect of decoherence may be ignored in the limit of infinite acceleration when the system interacts with a bit flip channel. Furthermore, a sudden rebirth of the one-tangle and π-tangle occur in the case of phase flip channel that may be delayed when collective coupling is switched on.

2025, Mathematical Structures in Computer Science

In this paper we study the dynamics of entanglement in some hybrid qubit–qutrit systems under the influence of global, collective, local and multilocal depolarising noise. We show that depolarising noise can be used to induce entanglement. A critical point exists under every coupling of the system with the environment at which all the states are equally entangled. Furthermore, we show that no ESD occurs when either only the qubit is coupled to its local environment or the system is coupled to a multilocal or global environment. This is an important result for various quantum information processing tasks and thus merits further investigation.

2025, arXiv (Cornell University)

A novel quantum pattern recognition scheme is presented, which combines the idea of a classic Hopfield neural network with quantum adiabatic computation. Both the input and the memorized patterns are represented by means of the problem Hamiltonian. In contrast to classic neural networks, the algorithm can simultaneously return multiple recognized patterns. The approach also promises extension of classic memory capacity. A proof of principle for the algorithm for two qubits is provided using a liquid state NMR quantum computer.

2025, Chibuihe (Laudauer’s principle published

We introduce a synchronization procedure for clocks based on the Einstein-Landauer framework. Clocks are modeled as discrete, macroscopic devices operating at a thermal equilibrium temperature T. Synchronization is achieved by transmitting photons from one clock to another; the absorption of a photon by a clock reduces the uncertainty in its timekeeping. The minimum energy required for this reduction in uncertainty is determined by the Landauer bound. We distinguish between the time-bearing and non-time-bearing degrees of freedom of the clocks. A reduction in uncertainty under synchronization in the time-bearing degrees of freedom necessarily leads to heat dissipation in the nontime-bearing ones. The minimum energy dissipation in these non-time-bearing degrees of freedom is likewise given by the Landauer limit. The same is true for mechanical synchronization of clocks. We also consider lattices of clocks and analyze synchronization using a Ramsey graph approach. Notably, clocks operating at the same temperature may be synchronized using photons of different frequencies. Each clock is categorized as either synchronized or non-synchronized, resulting in a bi-colored complete graph of clocks. By Ramsey's theorem, such a graph inevitably contains a triad (or loop) of clocks that are either all synchronized or all non-synchronized. The extension of the Ramsey approach to infinite lattices of clocks is reported.

2025

We investigate a theoretical framework in which a fundamental quantum of energy, termed the joulino (), and a fundamental unit of length, the metrino (), define the discrete structure of spacetime. By hypothesizing a relation between the Planck constant, energy-time uncertainty, and a spacetime energy density comparable to that of a neutron star, we derive approximate values for and. We then discuss how such a model might impose computational limits, potentially offering an explanation for the quantum barren plateau phenomenon in variational quantum algorithms.

2025, Advances in Atomic Molecular, and Optical Physics, Vol 53

II. Single-photon light fields 2 A. Frequency modes 3 B. Spatiotemporal modes 3 C. Single-photon detection 3 III. Two-photon interference 4 A. Quantum description of the beam splitter 4 B. Principle of the two-photon interference 5 C. Temporal aspects of the two-photon interference 5 D. Correlation function 6 E. Two-photon interference without time resolution 7 F. Time-resolved two-photon interference 7 IV. Jitter 9 A. Frequency jitter 9 B. Emission-time jitter 10 C. Autocorrelation function of the photon's shape 11 V. Experiment and Results 12 A. Single-photon source and experimental setup 12 B. Average detection probability 13 C. Time-resolved two-photon interference 13 D. Interpretation of the results 15 Acknowledgments 16 It is a pleasure for us to dedicate this paper to Prof. Herbert Walther, a pioneer in quantum optics from the very beginning. The investigation of the amazing properties of single photons both in the microwave and the optical domain has always been a central theme in his research. We wish him all the best in the years to come!

2025, Nature Physics

Neutral atoms are ideal objects for the deterministic processing of quantum information. Entanglement operations have been carried out by photon exchange 1 or controlled collisions 2 , and atom-photon interfaces have been realized with single atoms in free space 3,4 or strongly coupled to an optical cavity 5,6 . A long-standing challenge with neutral atoms, however, is to overcome the limited observation time. Without exception, quantum effects appeared only after ensemble averaging. Here, we report on a single-photon source with one, and only one, atom quasi-permanently coupled to a high-finesse cavity. 'Quasipermanent' refers to our ability to keep the atom long enough to, first, quantify the photon-emission statistics and, second, guarantee the subsequent performance as a single-photon server delivering up to 300,000 photons for up to 30 s. This is achieved by a unique combination of single-photon generation and atom cooling 7-9 . Our scheme brings deterministic protocols of quantum information science with light and matter 10-16 closer to realization. Deterministic single-photon sources are of prime importance in quantum information science 17 . Such sources have been realized with neutral atoms, embedded molecules, trapped ions, quantum dots and defect centres 18 . All of these sources are suitable for applications where the indivisibility of the emitted light pulses is essential. For quantum computing or quantum networking, the emitted photons must also be indistinguishable. Such photons have so far only been produced with quantum dots 19 and atoms . Another requirement is a high efficiency. This is hard to obtain in free space, as the light-collecting lens covers only a fraction of the full 4π solid angle. The efficiency can be boosted by strongly coupling the radiating object to an optical microcavity, as has been achieved with atoms 5,6 and quantum dots . An additional advantage of the cavity is that a vacuum-stimulated Raman adiabatic passage can be driven in a multilevel atom . In this way, the amplitude 5,24 , frequency 20 and polarization 25 of the photon can be controlled. It should also be possible to combine partial photon production with internal atomic rotations for the construction of entangled photon states such as W and GHZ states . All of these demands together have so far only been achieved with atoms in high-finesse microcavities. One reason is that neutral atoms are largely immune to perturbations, such as electric patch fields close to dielectric mirrors. However, atomic systems have always suffered from a fast atom loss. We have now implemented a cavity-based scheme, see Fig. , with a dipole laser for trapping, a trigger laser for photon generation and a recycling laser for Beam splitter Detector 1 Trigger and recycling laser Rb atom Cavity Dipole trap Detector 2

2025, Anais dos Seminários de Iniciação Científica

Nos últimos anos tem sido dado uma grande atenção à computação quântica e oseu interesse tem sido intensificado em função do desenvolvimento de algoritmos quepossibilitam a fatoração de números primos com velocidade superior à computação convencional.Algoritmos baseadas no controle de estados quânticos, ou simplesmente algoritmosquânticos, oferecem um ganho exponencial de eficiência em relação à algoritmosclássicos equivalentes. No entanto, a implementação experimental destes algoritmosesbarra em um grande obstáculo: a descoerência. Resultante da interação do sistemade interesse com o ambiente externo, a descoerência dificulta o controle de estadosquânticos e a realização das operações que compõem os algoritmos. A descoerêncialeva os estados a perderem gradualmente seu caráter quântico e, consequentemente, suautilidade em computação quântica fica comprometida. Para compreender a descoerênciadiversos modelos têm sido propostos. O mais geral requer a análise da interação entre osistem...

2025

We report the first experimental violation of fundamental quantum mechanics predictions achieved on enterprise-grade quantum hardware through implementation of a novel Quantum Harmonic Resonance Framework (QHRF). Using IBM's 133-qubit Torino processor, we demonstrate stabilization of quantum superposition states that violate the standard measurement postulate, achieving 20.04% probability for classically forbidden Bell states with 25σ statistical significance. Our proprietary QHRF protocol maintains coherent quantum superposition across multiple computational basis states post-measurement, directly contradicting von Neumann's projection postulate. The breakthrough establishes quantum harmonic resonance as a fundamental mechanism for transcending classical decoherence limitations, with immediate implications for fault-tolerant quantum computing, room-temperature superconductivity, and controlled fusion energy. These results represent the most significant advancement in quantum foundations since Bell's theorem, demonstrating that quantum mechanics requires fundamental extension to accommodate resonance-driven phenomena that enable revolutionary technological applications.

2025

We report the first experimental violation of fundamental quantum mechanics predictions on enterprisegrade quantum hardware, achieved through implementation of the Quantum Harmonic Resonance Framework (QHRF) on IBM's 133-qubit Torino processor. Our experiments demonstrate the stabilization of quantum superposition states that violate the standard measurement postulate, achieving 20.04% probability for classically forbidden Bell states with 25σ statistical significance. The QHRF protocol implements parametric resonance injection and cross-resonator coupling to maintain coherent quantum superposition across all four computational basis states post-measurement, directly contradicting von Neumann's projection postulate. Cross-platform validation on both real hardware (IBM Torino job ID: d1i6okb9fb3c73edlag0) and noise-calibrated simulators confirms reproducibility with forbidden state detection ranging from 20-30%. These results represent the most significant advancement in quantum foundations since Bell's theorem, establishing QHRF as a fundamental extension to quantum field theory with immediate applications to fault-tolerant quantum computing, room-temperature superconductivity, and controlled fusion energy. The breakthrough demonstrates that quantum mechanics, while extraordinarily successful, requires extension to accommodate resonance-driven coherence stabilization phenomena that transcend classical decoherence limitations.

2025, arXiv (Cornell University)

In variational quantum algorithms (VQAs), the most common objective is to find the minimum energy eigenstate of a given energy Hamiltonian. In this paper, we consider the general problem of finding a sufficient control Hamiltonian structure that, under a given feedback control law, ensures convergence to the minimum energy eigenstate of a given energy function. By including quantum non-demolition (QND) measurements in the loop, convergence to a pure state can be ensured from an arbitrary mixed initial state. Based on existing results on strict control Lyapunov functions, we formulate a semidefinite optimization problem, whose solution defines a non-unique control Hamiltonian, which is sufficient to ensure almost sure convergence to the minimum energy eigenstate under the given feedback law and the action of QND measurements. A numerical example is provided to showcase the proposed methodology.

2025, Linear Algebra and its Applications

Let G be a simple undirected graph. Let 0 ≤ α ≤ 1. Let where D(G) and A(G) are the diagonal matrix of the vertex degrees of G and the adjacency matrix of G, respectively. Let p(G) > 0 and q(G) be the number of pendant vertices and quasi-pendant vertices of G, respectively. Let m G (α) be the multiplicity of α as an eigenvalue of with equality if each internal vertex is a quasi-pendant vertex. If there is at least one internal vertex which is not a quasi-pendant vertex, the equality is determined in which m N (α) is the multiplicity of α as an eigenvalue of the matrix N . This matrix is obtained from A α (G) taking the entries corresponding to the internal vertices which are non quasi-pendant vertices. These results are applied to search for the multiplicity of α as an eigenvalue of A α (G) when G is a path, a caterpillar, a circular caterpillar, a generalized Bethe tree or a Bethe tree. For the Bethe tree case, a simple formula for the nullity is given.

2025, Bulletin of the American …

We present experimental efforts toward the creation of ultracold gas of KRb polar molecules. We start by creating extremely weakly bound molecules using a magnetic-field Feshbach resonance. This ultracold dense sample of Feshbach... more

2025

Quantum logic in Group-II neutral atoms via nuclear-exchange interactions DAVID HAYES, IVAN DEUTSCH, UNM, PAUL JULIENNE, NIST -The spin exchange-interaction provides a means of producing an entangling quantum-logic gate, the square-root of SWAP, at the heart protocols employing single electron quantum dots. This is typically accompanied by strong Coulomb interactions and commensurate decoherence due to strong coupling of charge degrees of freedom to the noisy environment. We propose a protocol utilizing a nuclearexchange interaction that occurs through ultra-cold collisions of identical spin 1 / 2 Group-II neutral atoms. A natural advantage is gained by storing the quantum information in nuclear spin states with long coherence times. Unlike NMR protocols based on weak magnetic dipole-dipole interaction, the nuclear exchange interaction stems from strong s-wave scattering of electrons. Nuclear exchange is ensured by the Fermi symmetry of the overall wave function. We have studied this protocol in the context of 171 Yb atoms trapped in far-off resonance optical dipole traps. Using numerical analysis, we show that high-fidelity operation is possible through controlled collisions in varied double-well trapping potentials.

2025

and the National Institute of Standards and Technology -We will discuss recent computational work that employs both direct quantum Monte Carlo simulation and inhomogeneous dynamical meanfield theory to study the efficiency of preforming KRb pairs in an optical lattice. We will describe how to optimize the efficiency by adjusting the lattice depth and the interspecies interaction (via the Feshbach resonance) with parameters specific for fermionic 40 K and bosonic 87 Rb (since the ground-state dipolar molecule has already been formed from those atoms in free space). We work with a deep enough lattice that the K atoms are mobile, but the Rb atoms are localized, so the system is described by the spinless Falicov-Kimball model on a two-dimensional lattice. We also calculate the entropy and estimate the temperature that one can achieve by cooling the atoms and adiabatically turning on the lattice.