A preliminary model of meaningful quanta of information arising from the quantum vacuum, and giving rise to the elementary quantum fields, is presented. We attempt to establish an equivalence of information and physical action, with the quanta (or packets of words) of information as a source of quantum fields (with a possible role in governing the interactions among those), similar to the quantum fields being the source of classical information. The information and quantum fields emerge in an entangled form out of the quantum vacuum, with their common underlying basis bearing intrinsically both a well-defined deterministic (geometric) and probabilistic (stochastic) structure. The description of equivalent energy of a quantum of the electromagnetic field, in terms of its information content, as well as an expression of the signal power, is provided. Various aspects of this problem and its possible implications and repercussions on our understanding of elementary quantum fields and their interactions are discussed. It is suggested that information, in a deterministic form, as well as chaotic processes within the quantum vacuum, give rise to a possible condensation of information into quantum fields.
Based on the concepts of the quantum field theory of virtual photons as quanta of electromagnetic interaction, we discuss the physical content of the phenomena underlying the principle of quantum uncertainties. We consider the features of the uncertainty relations and the properties of the elementary particles (electrons, protons, etc.) under the conditions of the formation of quantum bound states at atomic and subatomic distances.
The quantization of the electromagnetic field in vacuum is presented without reference to lagrangean quantum field theory. The equal time commutators of the fields are calculated from basic principles. A physical discussion of the commutators suggest that the electromagnetic fields are macroscopic emergent properties of more fundamental physical system: the photons.
The free electromagnetic field, solution of Maxwell's equations and carrier of energy, momentum and spin, is construed as an emergent collective property of an ensemble of photons, and with this, the consistency of an interpretation that considers that the photons, and not the electromagnetic fields, are the primary ontology is established.
The purpose of this article is to show that the standard method of introducing the quantum description of the electromagnetic field -- by canonical field quantization -- is not the only one. We have chosen instead as the starting point the relativistic quantum mechanics of photons. Our present understanding of the nature of photons significantly differs from what has been known years ago when the concept of a photon has only been emerging. We show how the description of photons treated as elementary particles merges smoothly with the classical description of the electromagnetic field and leads…
An antisymmetric tensor, the photon tensor, is defined for the description of the photon as a massless relativistic particle. The photon can be visualized as an essentially two dimensional rotating object. The quantum mechanical description of a single photon is presented and it is shown that it is wrong to associate the quantum states of a photon with the macroscopic electromagnetic fields. This work is part of a series devoted to the attempt to understand the quantum of electromagnetic radiation, based on the assumption that the photons are the primary ontology and that the electromagnetic f…
We use quantum-electrodynamical approach to study the initial stage of Dicke superradiance from a system of two-level atoms. Applying the zeroth-order Magnus approximation, we obtain the expression for the mean number of quanta emitted in the presence of thermal fluctuations of the electromagnetic field.
Quantum oscillators prepared out of thermal equilibrium can be used to produce work and transmit information. By intensive cooling of a single oscillator, its thermal energy deterministically dissipates to a colder environment, and the oscillator substantially reduces its entropy. This out-of-equilibrium state allows us to obtain work and to carry information. Here, we propose and experimentally demonstrate an advanced approach, conditionally preparing more efficient out-of-equilibrium states only by a weak dissipation, an inefficient quantum measurement of the dissipated thermal energy, and s…
In this paper, I argue that light is a continuous classical electromagnetic wave, while the observed so-called quantum nature of the interaction of light with matter is connected to the discrete (atomic) structure of matter and to the specific nature of the light-atom interaction. From this point of view, the Born rule for light is derived, and the double-slit experiment is analysed in detail. I show that the double-slit experiment can be explained without using the concept of a "photon", solely on the basis of classical electrodynamics. I show that within this framework, the Heisenberg uncert…
Quantum information technology is one of the fastest growing sectors within information technology. By misleading interpretations of Bohr's definition of complementarity, the foundation of nonlocal correlations of entanglement is concealed and therefore, such nonlocal effects can apparently not be utilized directly in information technology. As the first step to identify the utilizable nonlocal property of entanglement, this paper adjusts the notion of complementarity of first-order and second-order interference. Especially, the nonlocal consequence of the "principle of least action" for entan…
The ignition of two-quantum collective emission of inverted sub-ensemble of radiators due to mutual interaction of this sub-ensemble with other two dipole active atomic subsystems in process of two-photon exchanges between the atoms through the vacuum field is proposed. The three particle resonances between two-photon and single quantum transitions of inverted radiators from the ensemble are proposed for acceleration of collective decay rate of bi-photons, obtained relatively dipole-forbidden transitions of excited atomic sub-ensemble. This mutual interaction between three super-fluorescent pr…
The Schrödinger theory of electrons in an external electromagnetic field can be described from the perspective of the individual electron via the `Quantal Newtonian' laws (or differential virial theorems). These laws are in terms of `classical' fields whose sources are quantal expectations of Hermitian operators taken with respect to the wave function. The laws reveal the following physics: (a) In addition to the external field, each electron experiences an internal field whose components are representative of a specific property of the system such as the correlations due to the Pauli exclusio…
The coherence properties of the classical waves are discussed in terms of the Cauchy problem for the wave equation, and of a discrete representation by an ensemble of Hamiltonian systems. Wave quanta are related to specific "action fields", and phase-space distributions of phonons and photons are obtained by Wigner transform. For photons in a thermal environment, the proposed Wigner function evolves towards the Planck equilibrium distribution. It is shown that the free electromagnetic field can also be found in states of definite helicity, described by a complex vector potential.
It is shown that the geometry of quantum theory can be derived from geometrical structure that may be considered more fundamental. The basic elements of this reconstruction of quantum theory are the natural metric on the space of probabilities (information geometry), the description of dynamics using a Hamiltonian formalism (symplectic geometry), and requirements of consistency (Kähler geometry). The theory that results is standard quantum mechanics, but in a geometrical formulation that includes also a particular case of a family of nonlinear gauge transformations introduced by Doebner and Go…
A system of two closely spaced atoms interacting through a vacuum electromagnetic field is considered. It is demonstrated that radiative decay in such a system resulting from photon exchange gives rise to a definite amount of information related to interatomic communication. Joint distributions of detection probabilities of atomic quanta and the corresponding amount of communication information are calculated.
Photons, i.e. the basic energy quanta of monochromatic waves, are highly non-localised and occupy all available space in one dimension. This non-local property can complicate the modelling of the quantised electromagnetic field in the presence of optical elements that are local objects. Therefore, in this paper, we take an alternative approach and quantise the electromagnetic field in position space. Taking into account the negative- {\em and} the positive-frequency solutions of Maxwell's equations, we construct annihilation operators for highly-localised field excitations with bosonic commuta…
Setups in which a system Alice emits field quanta which a system Bob receives are prototypical for wireless communication and have been extensively studied. In the most basic setup, Alice and Bob are modelled as Unruh-DeWitt detectors for scalar quanta and the only noise in their communication is due to quantum fluctuations. For this basic setup we here construct the corresponding information-theoretic quantum channel. We calculate the classical channel capacity as a function of the spacetime separation and we confirm that the classical as well as the quantum channel capacity are strictly zero…
Quantum optics is a field of research based on the quantum theory of light. Here, we show that the classical theory of light can be equally effective in explaining a cornerstone of quantum optics: the quantization of the free radiation field. The quantization lies at the heart of quantum optics and has never been obtained classically. Instead, we find it by taking into account the degeneracy of the spherical harmonics that appear in multipole terms of the ordinary Maxwell theory of the free electromagnetic field. In this context, the number of energy quanta is determined by a finite countable …
A scalable, multiplexed ion trap for quantum information processing is fabricated and tested. The trap design and fabrication process are optimized for scalability to small trap size and large numbers of interconnected traps, and for integration of control electronics and optics. Multiple traps with similar designs are tested with Cd+, Mg+, and Sr+ ions at room temperature and with Sr+ at 6 K, with respective ion lifetimes of 90 s, 300 +/- 30 s, 56 +/- 6 s, and 4.5 +/- 1.1 hours. The motional heating rate for Mg+ at room temperature and a trap frequency of 1.6 MHz is measured to be 7 +/- 3 qua…
Fast control of quantum systems is essential in order to make use of quantum properties before they are degraded by decoherence. This is important for quantum-enhanced information processing, as well as for pushing quantum systems into macroscopic regimes at the boundary between quantum and classical physics. Bang-bang control attains the ultimate speed limit by making large changes to control fields on timescales much faster than the system can respond, however these methods are often challenging to implement experimentally. Here we demonstrate bang-bang control of a trapped-ion oscillator us…
Present protocols of criticality-enhanced sensing with open quantum sensors assume direct measurement of the sensor and omit the radiation quanta emitted to the environment, thereby potentially missing valuable information. Here we propose a protocol for criticality-enhanced sensing via continuous observation of the emitted radiation quanta. Under general assumptions, we establish a scaling theory for the global quantum Fisher information of the joint system and environment state at dissipative critical points. We derive universal scaling laws featuring transient and long-time behavior governe…
We investigate the possibility of performing quantum tomography on a single qubit with generalized partial measurements and the technique of measurement reversal. Using concepts from statistical decision theory, we prove that, somewhat surprisingly, no information can be obtained using this scheme. It is shown that, irrespective of the measurement technique used, extraction of information from single quanta is at odds with other general principles of quantum physics.
We revisit the idea of quantum nondemolition measurement (QND) of optical quanta via a resonantly enhanced Kerr nonlinearity taking into account quantum back action and show that the monolithic microcavities enable QND measurement of number of quanta in a weak signal field using a spatially overlapping classical probe field. Due to the cross-phase modulation effect, the phase of the probe field acquires information about the signal number of quanta without altering it. We find the exact solution to the Heisenberg equations of motion of this system and calculate the measurement error, accountin…
The Schrödinger-Pauli theory of electrons in the presence of a static electromagnetic field can be described from the perspective of the individual electron via its equation of motion or `Quantal Newtonian' first law. The law is in terms of `classical' fields whose sources are quantum-mechanical expectation values of Hermitian operators taken with respect to the wave function. The law states that the sum of the external and internal fields experienced by each electron vanishes. The external field is the sum of the binding electrostatic and Lorentz fields. The internal field is the sum of field…
A closed vacuum-dominated Friedmann universe is asymptotic to a de Sitter space with a cosmological event horizon for any observer. The holographic principle says the area of the horizon in Planck units determines the number of bits of information about the universe that will ever be available to any observer. The wavefunction describing the probability distribution of mass quanta associated with bits of information on the horizon is the boundary condition for the wavefunction specifying the probability distribution of mass quanta throughout the universe. Local interactions between mass quanta…
By looking at quantum data compression in the second quantisation, we present a new model for the efficient generation and use of variable length codes. In this picture lossless data compression can be seen as the {\em minimum energy} required to faithfully represent or transmit classical information contained within a quantum state. In order to represent information we create quanta in some predefined modes (i.e. frequencies) prepared in one of two possible internal states (the information carrying degrees of freedom). Data compression is now seen as the selective annihilation of these quanta…
Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper limit on the OAM content per photon is known, they are also interesting systems to experimentally challenge quantum mechanical prediction for high quantum numbers. Here, we take advantage of a recently developed technique to imprint unprecedented high values of OAM, namely spiral phase mirrors (SPM), to generate photons with more than 10,000 quanta of OAM. More…
It is believed that no information can be stored in Hawking radiation, because correlations between quanta of different field modes vanish. However, such correlations have been defined only with reference to a single moment of time. In this article, we develop a method for the evaluation of {\em multi-time} correlations. We find that these correlations are highly non-trivial: for a scalar field in the Schwarzschild black hole, multi-time correlations have an explicit dependence on angular variables and on the scattering history of Hawking quanta. This result leads us to the conjecture that som…
The back reactions of Hawking radiation allow nontrivial correlations between consecutive Hawking quanta, which gives a possible way of resolving the paradox of black hole information loss known as the hidden messenger method. In a recent work of Ma {\it et al} [arXiv:1711.10704], this method is enhanced by a general derivation using small deviations of the states of Hawking quanta off canonical typicality. In this paper, we use this typicality argument to study the effects of generic back reactions on the quantum geometries described by spin network states, and discuss the viability of entrop…
The black hole information paradox presumes that quantum field theory in curved spacetime can provide unitary propagation from a near-horizon mode to an asymptotic Hawking quantum. Instead of invoking conjectural quantum gravity effects to modify such an assumption, we propose a self-consistency check. We establish an analogy to Feynman's analysis of a double-slit experiment. Feynman showed that unitary propagation of the interfering particles, namely ignoring the entanglement with the double-slit, becomes an arbitrarily reliable assumption when the screen upon which the interference pattern i…
The interference of quanta lies at the heart of quantum physics. The multipartite generalization of single-quanta interference creates entanglement, the coherent superposition of states shared by several quanta. Entanglement allows non-local correlations between many quanta and hence is a key resource for quantum information technology. Entanglement is typically considered to be essential for creating non-local correlations, manifested by multipartite interference. Here, we show that this is not the case and demonstrate multiphoton non-local quantum interference without entanglement of any int…
In quantum optics it is usual to describe the basic energy quanta of the electromagnetic (EM) field, photons, in terms of monochromatic waves which have a definite energy and momentum, and satisfy bosonic commutation relations. Taking this approach, however, leads to several no-go theorems regarding the localisability and superluminal propagation of single photons. Unfortunately, without a local quantum description of the EM field it becomes difficult to describe the specific dynamics of light in the presence of local interactions or local boundary conditions. In this thesis we take an alterna…
The black hole information loss paradox has plagued physicists since Hawking's discovery that black holes evaporate thermally in contradiction to the unitarity expected by quantum mechanics. Here we show that one of the central presumptions of the debate is incorrect. Ensuring that information not escape during the semi-classical evaporation process does not require that all the information remain in the black hole until the final stages of evaporation. Using recent results in quantum information theory, we find that the amount of information that must remain in the black hole until the final …
The relativistic quantum dynamics of an electron in an intense single-mode quantized electromagnetic field is investigated with special emphasis on the spin degree of freedom. In addition to fast spin oscillations at the laser frequency, a second time scale is identified due to the intensity dependent emissions and absorptions of field quanta. In analogy to the well-known phenomenon in atoms at moderate laser intensity, we put forward the conditions of collapses and revivals for the spin evolution in laser-driven electrons starting at feasible $10^{18}$ W/cm$^2$.
In the non-Markovian regime, the bath has the memory about the past behavior of the open quantum system. This memory has slowly-decaying power-law tails. Such a long-range character of the memory complicates the description of the resulting real-time dynamics on large time scales. In a numerical simulation, this problem manifests itself in a `revival', a spurious reflected signal which appears after a finite time thus invalidating the simulation. In the present work, we approach this problem and develop a numerical discretization of the bath without revivals. We find that a crucial role is pla…
Center Leo Apostel for Interdisciplinary Studies（里奥·阿波斯泰尔跨学科研究中心）；Brussels Free University（布鲁塞尔自由大学）
In previous research, we showed that 'texts that tell a story' exhibit a statistical structure that is not Maxwell-Boltzmann but Bose-Einstein. Our explanation is that this is due to the presence of 'indistinguishability' in human language as a result of the same words in different parts of the story being indistinguishable from one another. In the current article, we set out to provide an explanation for this Bose-Einstein statistics. We show that it is the presence of 'meaning' in 'stories' that gives rise to the lack of independence characteristic of Bose-Einstein, and provides conclusive e…
Parikh and Wilczek formulated Hawking radiation as quantum tunneling across the event horizon proving the spectrum to be nonthermal. These nonthermality factors emerging due to back reaction effects have been claimed to be responsible for correlations among the emitted quanta. It has been proposed by several authors in literature that these correlations actually carry out information locked in a black hole and hence provide a resolution to the long debated black hole information paradox. This paper demonstrates that this is a fallacious proposition. Finally, it formulates the implications of t…
We present a new method by which, in principle, it is possible to "see in absolute darkness," i.e., without exchanging any real quanta through quantum fields. This is possible because objects modify the mode structure of the vacuum in their vicinity. The new method probes the mode structure of the vacuum through the Unruh effect, i.e., by recording the excitation rates of quantum systems that are accelerated.
In recent years, the import of quantum information techniques in quantum gravity opened new perspectives in the study of the microscopic structure of spacetime. We contribute to such a program by establishing a precise correspondence between the quantum information formalism of tensor networks (TN), in the case of projected entangled-pair states (PEPS) generalised to a second-quantized framework, and group field theory (GFT) states, and by showing how, in this quantum gravity approach, discrete spatial manifolds arise as entanglement patterns among quanta of space, having a dual representation…
