Quantum Objects Research Articles

Resolving the gravitational redshift across a millimetre-scale atomic sample.

Einstein's theory of general relativity states that clocks at different gravitational potentials tick at different ratesrelative to lab coordinates-an effect known as the gravitational redshift1. As fundamental probes of space and time, atomic clocks have long served to test this prediction at distance scales from 30 centimetres to thousands of kilometres2-4. Ultimately, clocks will enable the study of the union of general relativity and quantum mechanics once they become sensitive to the finite wavefunction of quantum objects oscillating in curved space-time. Towards this regime, we measure a linear frequency gradient consistent with the gravitational redshift within a single millimetre-scale sample of ultracold strontium. Our result is enabled by improving the fractional frequency measurement uncertainty by more than a factor of 10, now reaching 7.6 × 10-21. This heralds a new regime of clock operation necessitating intra-sample corrections for gravitational perturbations.

Optical Excitation of Converging Surface Acoustic Waves in the Gigahertz Range on Silicon.

The optical excitation and propagation of converging surface acoustic waves on silicon with orientations (001) and (111) have been experimentally studied. An axicon-assisted formation of an annular irradiated region on the sample surface served as a source for converging surface waves. Surface wave patterns at different times were recorded using a Sagnac interferometer with spatial resolution. A study of the field distribution at the focus showed that, in spite of elastic anisotropy, which generally leads to aberrations, the acoustic energy can be concentrated into a spot with dimensions close to the diffraction limit. An asymmetric excitation distribution makes it possible to control the structure of the converged wave field at the focus, providing an effective tool for all-optical diagnostics of the local crystal structure as well as electronic properties of quantum objects embedded in the solid-state matrix.

Нейромережа Хопфілда як відкрита динамічна система

The paper provides an analysis of a Hopfield neural network model from the standpoint of the concept of open dynamic systems (ODS) offered earlier. According to it, the evolution of the universe can be represented as a sequence of stages of the ODS development, during which more and more complex ODSs were formed. Living cells were later formed from them and their further development led to the appearance of humans and their intelligence, the formation of civilization, and the emergence of artificial intelligence. An overview of the provisions of the ODS concept is presented and the stage of the emergence of life as a collective development of ODS in the form of populations of the offspring of the mother cell, that led to the emergence of complex organisms, the nervous system, human, and intelligence as an intangible form of the ODS development, is analyzed in detail. It has been suggested that transforming an inanimate macromolecule of ODS into a living cell is connected with the appearance in its composition of a multistable component like a Hopfield network, whose prototype – spin glass – is a quantum object that existed even before the emergence of life on Earth. To verify it, there has been car-ried out a detailed analysis of the Hopfield network model as a linear manifold stretched over a set of memorized data vectors. New evidence of the network convergence process coinciding is presented, and the source of energy that a living cell requires for reproduction is revealed. In the paper, a structure of a living ODS that is similar to the Hopfield network and supplemented with a reproduction module similar to a DNA molecule is offered. It fully corresponds to the struc-ture of the first bacteria on Earth detected by archaeologists. The results of the study confirm the efficiency of the methods of the ODS concept when studying the dynamics of the develop-ment of systems of different natures, including the latest artificial intelligence systems whose behavior may not be controlled.

Entanglement Levels Up

Extending a key resource of quantum technology, entanglement—either by having more than two quantum objects or using "qudits" instead of "qubits"-offers prospects for improvements in quantum communications, computation and other technologies.

Magnet Strength Dependence of Levitated Magnets in a Microwave Cavity

We report on the behavior of a superconducting microwave cavity containing levitated permanent magnets having a range of magnet strengths. By observing the changes in the cavity’s loaded quality factor and resonance frequency as functions of temperature and magnet remanence, we gain an understanding of the transient motion of the magnet as well as its steady-state levitation height when the temperature drops below 1 K. Experimental measurements of Meissner-effect levitation within a 10 GHz superconducting aluminum coaxial quarter-wave stub cavity are performed for a sequence of identically shaped millimeter-scale neodymium magnets having varying strengths. Magnet levitation within the cavity is accompanied by both gradual and abrupt shifts in the resonance frequency (with a height sensitivity as large as 400 MHz/mm) as well as changes in the total quality factor (8%-17%) as a function of temperature during the superconducting transition of the aluminum cavity. Prior to magnet motion and levitation, the Q of the cavity changes quadratically with temperature, as expected, as the walls of the cavity undergo the superconducting transition. We observe, however, a deviation from the quadratic trend which is attributable to magnet movement within the cavity. Such an electromechanical system is a transducer between mechanical and microwave oscillators enabling coupling of low-frequency mechanical motion of the magnet to other quantum objects, such as magnons and transmons, which are used for sensing and quantum information processing.

Фізичні основи квантової інформатики: від квантової механіки, через квантові обчислення до квантової криптографії

A methodical analysis of the basic problem related to quantum calculations of parameters of physical systems was made. Emphasis is placed on the physical principles of the operation of a quantum computer, with an emphasis on the fact that simultaneous access to all quantum states is important in quantum computing, which allows the simultaneous change of the quantum state from all superpositions in the qubit system. Emphasis is placed on the fact that in quantum algorithms the Fourier transform and the Hadamard transform are the basic operations - as a simple discrete Fourier transform. The reader's attention is drawn to the fact that quantum computing is primarily implemented in quantum objects with the properties of elementary NOT gates and controlled CNOT, which can be implemented on a Mach-Zehnder interferometer using the phenomena of photon interference and rotation of its polarization vector. Despite the progress of conventional computers, the need for the development of quantum computing is due to the technological limitation due to the dimensional quantization of the electronic spectrum and the exponential increase in the time of calculations by classical algorithms when the volume of data increases. However, the widespread use of quantum computers is limited by a number of problems. This is, first of all, insufficient accuracy and high sensitivity to external influences that can destroy the quantum state. Therefore, to increase the accuracy of calculations on a quantum computer, the calculation algorithm must be repeated a certain number of times, and to avoid the destruction of the quantum states of the qubit, low temperatures are used.

Heuristic Solution to the Conundrum of the <i>Zitterbewegung</i>

Assuming the Dirac wavefunction describes the state of a single particle. We propose that the relation derived by Schrödinger, which contains the Zitterbewegung term, is a position equation for an amplitude modulated wave. Namely, the elementary constituents are amplitude modulated waves. Indeed, we surmise that a second wave is associated with the particle, which corresponds to a signal. At the same time, we interpret that Broglie’s wave corresponds to a carrier. Furthermore, the quantum object is a recording medium and, like in a hologram, information encoded on its surface. We suggest a description and the cause of the Zitterbewegung heretofore never considered regarding the previous assertions. Hereunder, we shall also apply the quantum amplitude modulation interpretation to the single-photon wave function by Bialynicki-Birula. The predictions are testable, thence providing evidence for the proposed hypothesis.

The fine spectral tuning of plasmon mode and quantum emitter coupling and itscomparison with the dark-hot resonances

Localization of incident fields into very small volumes (hot-spots) allows strong light-matter interactions at the hot spots. This makes path interference effects, Fano resonances, visible. Fano resonances can appear due to the coupling of a bright plasmon (i) to a longer lifetime dark plasmon mode or (ii) to a quantum object (QO) of a much longer lifetime. The second phenomenon provides a very important utility: the voltage tunability of the linear/nonlinear response. The level-spacing of the QO, such as defect-centers and quantum dots, are voltage-tunable which can make a sharp Fano resonance appear and disappear. Here, we compare the two phenomena by solving the equations of motions for the near-field plasmon amplitudes, derived from two different Hamiltonians. While the two plasmon amplitudes look similar to each other, except for the population inversion parameter `$y$', our results show that quantum emitter enables fine spectral tuning of the plasmon amplitude, thus, providing better enhancement.

About the Observed Asymmetry between Matter and Antimatter

Some consequences, due to the existence of a pair of decoupled Schrödinger-like but relativistic quantum mechanics wave equations, are explored. It is shown that one equation directly describes the quantum states of a single spin-0 particle, and the other one indirectly describes the quantum states of the corresponding antiparticle. In correspondence with the matter-antimatter symmetry, for a Coulomb potential, a charge conjugation operation transforms the second equation in the first one. However, if a particle could interact with itself (gravitationally or electrically) due to the spread of its wavefunction, the C-symmetry could be broken; therefore, matter and antimatter could be distinguished. Under these assumptions, it is deducted the impossibility of the existence of particles and antiparticles with a mass larger than the Plank mass (mP), or with the absolute value of the charge larger than the Plank charge (qP). It is proposed the existence of primordial antimatter electrical sinks. It is also suggested that all macroscopic matter objects with a mass m > mP, and all macroscopic antimatter bodies with a charge |q| > qP should not be quantum but classical objects. It is argued that these findings could explain the absence of antimatter with a complicated structure and partially explain the excess of charged matter in the known Universe.

Quantum absentminded driver problem revisited

The aim of the paper is to study the problem of absentminded driver in the quantum domain. In the classical case, it is a well-known example of a decision problem with imperfect recall that exhibits lack of equivalence between mixed and behavioral strategies. The optimal payoff outcome is significantly lower than the maximum payoff appearing in the game. This raises the question whether a quantum approach to the problem can increase the strategic position of the decision maker. The results that we present in the paper clearly reveal the benefits from playing the absentminded problem with the aid of quantum objects. Through appropriately chosen initial quantum state, the unitary strategies enable the decision maker to obtain the maximum possible payoff. At the same time, our scheme comes down to the classical problem with a suitable restriction of unitary strategies.

The expression E = h × f is misleading because it implies the distribution of a photon quantum over 299 792 458 m, while the expression E = (h × c)/λ enables us to explain the particle-wave duality

The two equations E = h × f and E = (h × c)/λ for the quantum of energy of electromagnetic radiation provide the same result but describe electromagnetic radiation very differently. E = (h × c)/λ describes the quantum of energy of electromagnetic radiation to be located already in one wavelength and therefore like a particle. E = h × f describes the quantum of energy distributed over 299 792 458 m and therefore like a wave. To obtain h × f for the quantum of energy, we have to refer the quantum of energy to 299 792 458 m. Only then we obtain from E = (h × c)/(299 792 458 m), as the distance of 299 792 458 m of the velocity c is cancelling out now, E = h × 1/s = h × Hz, which is the precondition to obtain the correct value for the quantum of energy by multiplying Planck’s constant h by the frequency f. This already indicates the necessity of today's physics to have to speak of a particle-wave duality. It turns out that electromagnetic radiation consists of the first wavelength that carries the quantum of energy and behaves like a particle, which today is called “photon,” and a few following wavelengths that do not carry a further quantum of energy and behave like a wave, which today is called “electromagnetic wave.” By this knowledge, the particle-wave duality vanishes, and we obtain one single physical phenomenon, which I call “photon-wave.” The strange behavior of quantum objects at a single slit, at double-slits, and at beam splitters can now be understood in a causal way. “God does not play dice!” Einstein was right.

ON THE ROLE OF V. HEISENBERG, E. SCHRÖDINGER, K.F. WEIZSACKER, N. BOHR AND M. HEIDEGGER IN THE DEVELOPMENT OF THE LOGICAL AND MATHEMATICAL FOUNDATIONS OF QUANTUM PHYSICS

The development of the logical and mathematical foundations of quantum physics and, first of all, quantum mechanics is the work of a large team of physicists, mathematicians and philosophers who have contributed to the solution of this problem. The title of the article lists the names of four scientists who, according to the author, paved the way for the creation of quantum logic. This must be understood in such a way that from the very beginning (Heisenberg and Schrödinger) it was established that the properties of quantum objects are described not by numbers, but by operators. In the relationships of the operators themselves, one could see an analogue of Boolean algebra of classical logic. Weizsäcker raised the question of how the physical quantity of time, in describing the motion states of quantum objects, can be represented: an operator or a state vector? The author of the article shows that the development of quantum mechanics has gone through two stages. The first stage differs in that complex numbers and functions were introduced into physics, in other words, elements of the theory of functions of a complex variable. At the second stage, spinor calculus penetrated into quantum physics. If at the first stage methods were presented for describing the external degrees of freedom (motion) of elementary particles and other quantum objects, then the second stage was marked by the description of internal degrees of elementary particles. It became possible to understand that the measured mass of an electron or any other fermion is an averaged quantity, it consists of two ingredients: a positive mass and a negative mass (two values of the corresponding operator). An important role in this discovery played the operation of dialectical negation (privation), borrowed from Heidegger's fundamental ontology.

Exceptional points in oligomer chains

Symmetry underpins our understanding of physical law. Open systems, those in contact with their environment, can provide a platform to explore parity-time symmetry. While classical parity-time symmetric systems have received a lot of attention, especially because of the associated advances in the generation and control of light, there is much more to be discovered about their quantum counterparts. Here we provide a quantum theory which describes the non-Hermitian physics of chains of coupled modes, which has applications across optics and photonics. We elucidate the origin of the exceptional points which govern the parity-time symmetry, survey their signatures in quantum transport, study their influence for correlations, and account for long-range interactions. We also find how the locations of the exceptional points evolve as a function of the chain length and chain parity, capturing how an arbitrary oligomer chain transitions from its unbroken to broken symmetric phase. Our general results provide perspectives for the experimental detection of parity-time symmetric phases in one-dimensional arrays of quantum objects, with consequences for light transport and its degree of coherence.

Structure-Dependent Accessibility of Phonon-Coupled Radiative Relaxation Pathways Probed by X-ray-Excited Optical Luminescence.

Rare-earth scheelites represent a diverse family of compounds with multiple degrees of freedom, which enables the incorporation of a wide range of lanthanide color centers. Precise positioning of quantum objects is attainable by the choice of alkali cations and lattice connectivity of polyanion units. Herein, we report the structure-dependent energy transfer and lattice coupling of optical transitions in La3+- and Dy3+-containing scheelite-type double and quadruple molybdates NaLa1-xDyx(MoO4)2 and Na5La1-xDyx(MoO4)4. X-ray excitation of La3+ core states generates excited-state electron-hole pairs, which, upon thermalizing across interconnected REO8 polyhedra in double molybdates, activate a phonon-coupled excited state of Dy3+. A pronounced luminescence band is observed corresponding to optical cooling of the lattice upon preferential radiative relaxation from a "hot" state. In contrast, combined X-ray absorption near-edge structure and X-ray-excited optical luminescence studies reveal that such a lattice coupling mechanism is inaccessible in quadruple molybdates with a greater separation of La3+-Dy3+ centers.

Quantum Internal Structure of Plasmons.

Plasmons are usually described in terms of macroscopic quantities such as electric fields and currents. However, as fundamental excitations of metals, they are also quantum objects with internal structure. We demonstrate that this can induce an intrinsic dipole moment which is tied to the quantum geometry of the Hilbert space of plasmon states. This quantum geometric dipole offers a unique handle for manipulation of plasmon dynamics via density modulations and electric fields. As a concrete example, we demonstrate that scattering of plasmons with a nonvanishing quantum geometric dipole from impurities is nonreciprocal, skewing in different directions in a valley-dependent fashion. This internal structure can be used to control plasmon trajectories in two dimensional materials.

Self-Bayesian aberration removal via constraints for ultracold atom microscopy.

High-resolution imaging of ultracold atoms typically requires custom high numerical aperture (NA) optics, as is the case for quantum gas microscopy. These high NA objectives involve many optical elements, each of which contributes to loss and light scattering, making them unsuitable for quantum backaction limited "weak" measurements. We employ a low-cost high NA aspheric lens as an objective for a practical and economical-although aberrated-high-resolution microscope to image 87Rb Bose-Einstein condensates. Here, we present a methodology for digitally eliminating the resulting aberrations that is applicable to a wide range of imaging strategies and requires no additional hardware. We recover nearly the full NA of our objective, thereby demonstrating a simple and powerful digital aberration correction method for achieving optimal microscopy of quantum objects. This reconstruction relies on a high-quality measure of our imaging system's even-order aberrations from density-density correlations measured with differing degrees of defocus. We demonstrate our aberration compensation technique using phase-contrast imaging, a dispersive imaging technique directly applicable to quantum backaction limited measurements. Furthermore, we show that our digital correction technique reduces the contribution of photon shot noise to density-density correlation measurements which would otherwise contaminate the desired quantum projection noise signal in weak measurements.

Diagrammatic quantum Monte Carlo study of an acoustic lattice polaron

We present a diagrammatic Monte Carlo study of a lattice polaron interacting with an acoustic phonon branch through the deformation potential. Weak and strong coupling regimes are separated by a self-trapping region where quantum resonance between various possible lattice deformations is seen in the ground-state properties, spectral function, and optical conductivity. This study shows that the acoustic lattice polaron represents a distinct quantum object with unique features, markedly different from any previously considered polaron model. In particular, the acoustic lattice polaron exhibits an interplay between long- and short wavelength acoustic vibrations, resulting in a composite phonon cloud which leads to the formation of multiple competing polaron states with a complex spectral response.

Quantum eraser from duality-entanglement perspective

Wave-particle duality is a bizarre feature at the heart of quantum mechanics which refers to the mutually exclusive dual attributes of quantum objects as the wave and the particle. Quantum eraser presents a counterintuitive aspect of the wave-particle duality. In this work, we show that quantum eraser can be quantitatively understood in terms of the recently developed duality--entanglement relation. In other words, we show that wave-particle-entanglement triality captures all the physics of the quantum erasure. We find that a controllable partial erasure of the which-path information is attainable, enabling the partial recovery of the quantum interference and extending the scope of the conventional quantum eraser protocols.

Exploring\ufeff electroencephalography with a model inspired by quantum mechanics

An outstanding issue in cognitive neuroscience concerns how the brain is organized across different conditions. For instance, during the resting-state condition, the brain can be clustered into reliable and reproducible networks (e.g., sensory, default, executive networks). Interestingly, the same networks emerge during active conditions in response to various tasks. If similar patterns of neural activity have been found across diverse conditions, and therefore, different underlying processes and experiences of the environment, is the brain organized by a fundamental organizational principle? To test this, we applied mathematical formalisms borrowed from quantum mechanisms to model electroencephalogram (EEG) data. We uncovered a tendency for EEG signals to be localized in anterior regions of the brain during “rest”, and more uniformly distributed while engaged in a task (i.e., watching a movie). Moreover, we found analogous values to the Heisenberg uncertainty principle, suggesting a common underlying architecture of human brain activity in resting and task conditions. This underlying architecture manifests itself in the novel constant KBrain, which is extracted from the brain state with the least uncertainty. We would like to state that we are using the mathematics of quantum mechanics, but not claiming that the brain behaves as a quantum object.

On delayed choice and quantum erasure in two-slit experiment for testing complementarity

The principle of complementarity is one of the cornerstones of quantum theory. The aim of this study was to advance our understanding of complementarity by analyzing the role of delayed choice and quantum erasers in two-slit experiments, and by proposing experiments for verifying the analysis. The analysis is based on models consisting of measurable spaces and probability measures involved in the experiments. The main findings are as follows: (a) The complementarity principle manifests itself in such a way that wave and particle behaviors cannot be simultaneously observed almost surely with respect to any single, fixed measure. (b) Described by different measures, complementary properties can coexist in the same experimental setup. (c) Which-way information will not preclude or erase interference fringes. (d) Delayed choice and quantum erasers are irrelevant to testing complementarity. (e) It is possible for us to know through which slit each quantum object passed almost surely with respect to the measure corresponding to the slit while the interference pattern is intact. Based on the experiments analyzed, realizable experiments are proposed for verifying the above results.