Photon Wave Research Articles

Pushing photon-pair generation rate in microresonators by Q factor manipulation.

Photon pairs generated by employing spontaneous nonlinear effects in microresonators are critically essential for integrated optical quantum information technologies, such as quantum computation and quantum cryptography. Microresonators featuring high-quality (Q) factors can offer simple yet power-efficient means to generate photon pairs, thanks to the intracavity field enhancement. In microresonators, it is known that the photon-pair generation rate (PGR) is roughly proportional to the cubic power of the Q factor. However, the upper limit on PGR is also set by the Q factor: a higher Q factor brings a longer photon lifetime, which in turn leads to a lower repetition rate allowing for photon flow emitted from the microresonator, constrained by the Fourier-transform limit. Exceeding this limit will result in the overlap of photon wave packets in the time domain, thus degrading the quantum character of single-photon light beams. To push the limit of PGR in a single resonator, we propose a method by harnessing the resonance linewidth-manipulated microresonators to improve the maximum achievable photon repetition rate while keeping the power efficiency. The maximum achievable PGR and power efficiency are thus balanced by leveraging the combination of low and high-Q resonances.

Event-based diffractive neural network chip for dynamic action recognition

Dynamic action recognition has promising applications in human–computer interaction, information encryption, and high-speed image processing. However, it is challenging for a high-dynamic scene due to the huge amount of data and the computation costs. Here, we have proposed an event-based diffractive neural network (EBDNN) chip to recognize human dynamic actions. An event camera with high dynamic range and high temporal resolution is used for dynamic action capture. Based on the approach of compressing dimensions, a series of static images can be obtained by superimposing the event frames of the intervals, which serve as the train dataset of a diffractive neural network with photon wave properties. Compared to a frame camera with the same temporal resolution, the required data volume is only 0.0048% of that, which greatly shortens the training time of the diffractive neural network on the computer and saves computing resources. Notably, the diffractive neural network was trained to perform image classification tasks at the speed of light with almost no energy consumption, and the diffractive devices, which includes 400 × 400 neurons, is printed based on the two-photon polymerization technology. In addition, the experimental accuracy was as high as 99.17%. Our work opens up a new direction for photoelectrically integrated intelligent device, paving the way for the development of real-time monitoring systems and other machine vision tasks, such as autonomous driving and video surveillance.

Photonic Millimeter Wave Generation and Stabilization in Optically Injected Discrete-Mode Semiconductor Lasers Subject to Photonic Filter Feedback

Photonic millimeter wave signal generation and stabilization based on nonlinear dynamics of optically injected discrete-mode semiconductor lasers with photonic filter feedback are experimentally and numerically studied. The photonic filter is constructed by jointing two ports of a 2×2 optical coupler to form a ring cavity recirculation and is modelled as an infinite impulse response filter. The results show that >30GHz photonic millimeter wave signals can be obtained after optical to electrical conversion of the period-one oscillation output of the optically injected discrete-mode semiconductor laser. More importantly, the linewidth, side peak suppression ratio, as well as the stability of the generated millimeter wave, can be optimized using the photonic filter feedback. A fair comparison of the photonic filter feedback scheme and the single/double optical feedback schemes in terms of optimization performance has been made. The corresponding results demonstrate that the photonic filter feedback scheme has obvious superiority in millimeter wave side peak suppression and stability. The effect of the coupling coefficient as well as the phase variables in the ring cavity has also been discussed in the simulation work and the results qualitatively agree with the experimental observations.

Explaining large electromagnetic logarithms from loops of inflationary gravitons

Recent progress on nonlinear sigma models on de Sitter background has permitted the resummation of large inflationary logarithms by combining a variant of Starobinsky’s stochastic formalism with a variant of the renormalization group. We reconsider single graviton loop corrections to the photon wave function, and to the Coulomb potential, in light of these developments. Neither of the two 1-loop results have a stochastic explanation, however, the flow of a curvature-dependent field strength renormalization explains their factors of ln(a). We speculate that the factor of ln(Hr) in the Coulomb potential should not be considered as a leading logarithm effect.

Susceptibility of a single photon wave packet

Susceptibility of a single photon wave packet

States, Modes, Fields, and Photons in Quantum Optics

The quantum nature of light enables potentially revolutionary communication technologies. A key to advancing this area of research is a clear understanding of the concepts of states, modes, fields, and photons. The concept of field modes carries over from classical optics, while the concept of state has to be considered carefully when treating light quantum mechanically. The term "photon" is an overloaded identifier in the sense that it is often used to refer to either a quantum particle or the state of a field. This overloading, often used without placing it in context, has the potential to obfuscate the physical processes that describe the reality we measure. We review the uses and relationships between these concepts using modern quantum optics theory, including the concept of a photon wave function, the modern history of which was moved forward in a groundbreaking paper in this journal by Iwo Białynicki-Birula, to whom this article is dedicated.

Photon Wave Function from the Vector Potential Quantization

Photon Wave Function from the Vector Potential Quantization

Gauge invariance and anomalies in condensed matter physics

This paper begins with a summary of a powerful formalism for the study of electronic states in condensed matter physics called “gauge theory of states/phases of matter.” The chiral anomaly, which plays quite a prominent role in that formalism, is recalled. I then sketch an application of the chiral anomaly in 1 + 1 dimensions to quantum wires. Subsequently, some elements of the quantum Hall effect in two-dimensional (2D) gapped (“incompressible”) electron liquids are reviewed. In particular, I discuss the role of anomalous chiral edge currents and of the anomaly inflow in 2D gapped electron liquids with explicitly or spontaneously broken time reversal, i.e., in Hall and Chern insulators. The topological Chern–Simons action yielding transport equations valid in the bulk of such systems and the associated anomalous edge action are derived. The results of a general classification of “Abelian” Hall insulators are outlined. After some remarks on induced Chern–Simons actions, I sketch results on certain 2D chiral photonic wave guides. I then continue with an analysis of chiral edge spin-currents and bulk response equations in time-reversal invariant 2D topological insulators of electron gases with spin–orbit interactions. The “chiral magnetic effect” in 3D systems and axion-electrodynamics are reviewed next. This prepares the ground for an outline of a general theory of 3D topological insulators, including “axionic insulators.” Some remarks on Weyl semi-metals, which exhibit the chiral magnetic effect, and on Mott transitions in 3D systems with dynamical axion-like degrees of freedom conclude this review.

Calculation and analysis of quantum radar scattering characteristics of targets in atmospheric medium.

Though much work has been done concerning quantum radar cross section (QRCS), the related question about quantum radar scattering characteristics of targets in the atmospheric medium has not been considered. Understanding this question is of primary significance in the military and civil fields of quantum radar. The main objective of the paper is to propose a new algorithm for the calculation of QRCS in homogeneous atmospheric medium (M-QRCS). Therefore, based on the chain of beam splitters proposed by M. Lanzagorta to describe homogeneous atmospheric medium, the photon attenuation model is established, the photon wave function is modified, and the M-QRCS equation is proposed. Furthermore, in order to obtain an accurate M-QRCS response, we carry out simulation experiments on a flat rectangular plate in the atmospheric medium composed of different atomic arrays. Based on this, we study the influence of the attenuation coefficient, temperature, and visibility on the intensity of the peak value of main lobe and side lobes of M-QRCS. In addition, it is worth noting that the numerical calculation method proposed in this paper is based on the interaction between photons and atoms on the target surface, so it is suitable for the calculation and simulation of M-QRCS for targets of any shape.

NOON-state generation and superresolved interference in a double-slit experiment

Maximally entangled NOON states are proposed to be generated with $N$ independent photons and a fixed double-slit in the Young's interference experiment. A strict condition is required that these photons have to be arranged in a straight line and separated from each other by certain equal distances. The initial product state turns into a NOON state of the photons at the double-slit, after $N$-photon postselected measurements. With a spatially random laser beam, we experimentally investigate the high-order correlation functions to imitate the behavior of the single-photon and $N$-photon wave packets of the NOON states. Since the $N$-photon wave packet is the product of $N$ single-photon wave packets, two methods are adopted to observe the superresolved fringes. The first method is to use the product of the second-order correlation functions. The second one is to measure the $2N\mathrm{th}$-order correlation functions. In the both cases, the superresolved fringes of up to fourth order are successfully observed.

The contribution of coherence field theory to a model of consciousness: electric currents, EM fields, and EM radiation in the brain.

A paradigm in neuroscience is developing which views resonance as the phenomenon responsible for consciousness. Much progress is being made in the investigation of how resonance as oscillating flows within the brain's electric field might result in production of mind from matter. But it's mostly unknown how vibrations among features of matter such as nanoscale atomic structures and photonic waves may participate in forming the basic substance of first-person consciousness, meaning percepts such as colors, textures, sounds, thoughts, feelings et cetera. Initial evidence at the leading edge of quantum biology suggests that light and atoms combine to form synchronously resonating structures of contiguous energy which I have termed coherence fields. My hypothesis is that coherence fields as atomic nodes within expanses of integrating photonic waves are the fundamental unit of first-person percepts insofar as they arise from electromagnetic matter. A concept of quantum coherence is formulated based on a new phenomenology of matter's nanoscale properties, and this is shown to tie what we have thus far discovered of neural anatomy into a comprehensive model of how electrical impulses travel through neurons as electron currents driven by coherence at the quantum scale. Transmembrane electric fields generated by ionic currents, synaptic phase regulation, and perhaps further mechanisms have been hypothesized as responsible for local field potentials (LFP) oscillations. Some insights into how emergent, macroscopic waves in the brain's electric field may reciprocally impact LFP propagation to control arousal, attention, and volition are briefly discussed. Activation of neural tissue is closely linked to temperature variation, and it is hypothesized that this is not merely a waste byproduct but constitutes a signature of coherence field modulation, with photonic waves of a primarily infrared spectral range functioning as an interstitial medium of the basic percept field. A variety of possible routes to coherence field modulation are outlined that derive from the mechanisms of electric currents, EM fields, EM radiation, and entanglement. If future experimental designs continue to validate coherence field theory, this could set science on course to resolve the mind/body problem.

Reformulating the Basics of Conventional Newtonian Physics, Quantum Physics and the Einstein Theories of Relativities Based on the newly discovered Topological Theory of Quantum Gravity (TTQG)

The Newtonian physics, quantum physics and the theories of relativity suffer from a major Incompleteness on the ground of being unable to offer the topologies and the dimensionalities of the numerous physical variables. Out of the three very familiar dimensions of physical variables in conventional physics length (L), mass (M) and time (T), the two variables, namely mass and time are fully arbitrary and abstract. In Newtonian physics L, M and T are fully independent variables since no mathematical equation linking the said three variables have been proposed. It is an established fact and a matter of everyday experience that L, M and T are very much linked to each other and otherwise which, the universe could have taken either the infinite number of shapes of desire arising out of endless permutations and combinations of L, M and T or could have merged to fully length (LM°T°) or fully mass (L°MT°) or fully time (L°M° T). Max Planck tied up the five numbers of basic physical variables, length, time, mass, electric charge and temperature to the same source by linking all of them to the Newton’s Gravitational constant (G) and Planck constant (h). However, this attempt was also incomplete since the topologies of G and h, could not be put forward. Later on, the quantum physics even, could not erase the stamp of ‘abstractness’ as put on the physical variables like mass, time, temperature, gravitation, photon waves and many others. Neither the Newtonian physics nor the quantum physics can depict the dimensionalities of entropy, force, energy, acceleration, black hole, plasma state, etc. and as well cannot also tell us how a ‘photon’ looks alike or what the ‘gravitons’ are in reality. The recently discovered topological theory of quantum gravity (TTQG) revealed the following: 1. The phenomenon of gravitation is being linked to the intermolecular attractive forces. 2. Have defined all the above said physical variables as ‘gravitons’ in regard to entropy. 3. Presented the topologies and dimensionalities of the physical variables. 4. Introduced the inverse dimensionality concept in physics. 5. Proposed the mathematical equation relating L, M and T 6. Reformulated the basics of Newtonian physics, quantum physics and the special and general theories of relativity. 7. All the cosmic phenomena of the universe have been represented by a singularity graviton originated universal graviton cycle.

Experimental demonstration of separating the wave‒particle duality of a single photon with the quantum Cheshire cat

As a fundamental characteristic of physical entities, wave‒particle duality describes whether a microscopic entity exhibits wave or particle attributes depending on the specific experimental setup. This assumption is premised on the notion that physical properties are inseparable from the objective carrier. However, after the concept of the quantum Cheshire cats was proposed, which makes the separation of physical attributes from the entity possible, the premise no longer holds. Furthermore, an experimental demonstration of the separation of the wave and particle attributes inspired by this scenario remains scarce. In this work, we experimentally separated the wave and particle attributes of a single photon by exploiting the quantum Cheshire cat concept for the first time. By applying a weak disturbance to the evolution of the system, we achieve an effect similar to the quantum Cheshire cat and demonstrated the separation of the wave and particle attributes via the extraction of weak values. Our work provides a new perspective for the in-depth understanding of wave‒particle duality and promotes the application of weak measurements in fundamentals of quantum mechanics.

Photon Structure and Wave Function from the Vector Potential Quantization

A photon structure is advanced based on the experimental evidence and the vector potential quantization at a single photon level. It is shown that the photon is neither a point particle nor an infinite wave but behaves rather like a local “wave-corpuscle” extended over a wavelength, occupying a minimum quantization volume and guided by a non-local vector potential real wave function. The quantized vector potential oscillates over a wavelength with circular left or right polarization giving birth to orthogonal magnetic and electric fields whose amplitudes are proportional to the square of the frequency. The energy and momentum are carried by the local wave-corpuscle guided by the non-local vector potential wave function suitably normalized.

Quantum Mechanics: Harmonic Wave-Packets, Localized by Resonant Response in Dispersion Dynamics

From a combination of Maxwell’s electromagnetism with Planck’s law and the de Broglie hypothesis, we arrive at quantized photonic wave groups whose constant phase velocity is equal to the speed of light c = ω/k and to their group velocity dω/dk. When we include special relativity expressed in simplest units, we find that, for particulate matter, the square of rest mass , i.e., angular frequency squared minus wave vector squared. This equation separates into a conservative part and a uniform responsive part. A wave function is derived in manifold rank 4, and from it are derived uncertainties and internal motion. The function solves four anomalies in quantum physics: the point particle with prescribed uncertainties; spooky action at a distance; time dependence that is consistent with the uncertainties; and resonant reduction of the wave packet by localization during measurement. A comparison between contradictory mathematical and physical theories leads to similar empirical conclusions because probability amplitudes express hidden variables. The comparison supplies orthodox postulates that are compared to physical principles that formalize the difference. The method is verified by dual harmonics found in quantized quasi-Bloch waves, where the quantum is physical; not axiomatic.

Broadband radio frequency signal measurement based on quantum compression sensing

With the rapid development of radio frequency technology such as radar, electronic warfare and 5G communication, the measurement and real-time spectrum characterization of broadband radio frequency signals become increasingly important. The traditional radio frequency signal real-time measurement technology is limited by the sampling rate of analog-to-digital converter and the ability to process digital signals, and encounters the problems of narrow measurement band, large data volume, and susceptibility to electromagnetic interference. This work is to study a radio frequency signal measurement technology based on quantum compression sensing, which uses integrated electro-optical crystal as radio frequency sensor, and constructs a compression sensing machine by modulating the photon wave function of the measured radio frequency signal to realize the compression measurement of broadband radio frequency signal, significantly improving the spectrum sensing bandwidth. The experiment demonstrates the long-term spectrum monitoring of power frequency and intermediate frequency high voltage signals, and the real-time spectrum measurement of high frequency radio frequency signals. Under the Fourier limit spectrum resolution, the real-time spectrum analysis bandwidth of GHz magnitude is realized, and the data compression rate reaches 1.7×10<sup>–5</sup>, which can meet the needs of 5G wireless communication, cognitive radio and other applications for broadband radio frequency signal spectrum measurement, and provide a new technical path for developing the next-generation broadband spectrum sensing technology.

Dark photon vortex formation and dynamics

We study the formation and evolution of vortices in U(1) dark photon dark matter and dark photon clouds that arise through black hole superradiance. We show how the production of both longitudinal mode and transverse mode dark photon dark matter can lead to the formation of vortices. After vortex formation, the energy stored in the dark photon dark matter will be transformed into a large number of vortex strings, eradicating the coherent dark photon dark matter field. In the case where a dark photon magnetic field is produced, bundles of vortex strings are formed in a superheated phase transition, and evolve towards a configuration consisting of many string loops that are uncorrelated on large scales, analogous to a melting phase transition in condensed matter. In the process, they dissipate via dark photon and gravitational wave emission, offering a target for experimental searches. Vortex strings were also recently shown to form in dark photon superradiance clouds around black holes, and we discuss the dynamics and observational consequences of this phenomenon with phenomenologically motivated parameters. In that case, the string loops ejected from the superradiance cloud, apart from producing gravitational waves, are also quantised magnetic flux lines and can be looked for with magnetometers. We discuss the connection between the dynamics in these scenarios and similar vortex dynamics found in type II superconductors.

Instantaneous Quantum Description of Photonic Wavefronts and Applications

Three physical elements are missing from the conventional formalism of quantum photonics: (1) the quantum Rayleigh spontaneous and stimulated emissions; (2) the unavoidable parametric amplification; and (3) the mixed time-frequency spectral structure of a photonic field which specifies its duration or spatial extent. As a single photon enters a dielectric medium, the quantum Rayleigh scattering prevents it from propagating in a straight-line, thereby destroying any possible entanglement. A pure dynamic and coherent state composed of two consecutive number states, delivers the correct expectation values for the number of photons carried by a photonic wave front, its complex optical field, and phase quadratures. The intrinsic longitudinal and lateral field profiles associated with a group of photons for any instantaneous number of photons are independent of the source. These photonic properties enable a step-by-step analysis of the correlation functions characterizing counting of coincident numbers of photons or intensities with unity visibility interference, spanning the classical and quantum optic regimes.

Stable terahertz wave dissemination over underground fiber network with optical phase correction

We report a phase-stabilized photonic terahertz wave distribution over an urban underground fiber network. The optical carriers of the terahertz signal are generated by filtering out optical spectral lines of an optical frequency comb (OFC). The phase fluctuation due to the optical carriers separation link and fiber link is compensated by an optical phase actuation network, which employs a high-precision voltage-controlled oscillator (VCO) in the phase-locked loop to drive the acousto-optic frequency shifter (AOFS) for fast phase correction We demonstrated the stabilized transfer of a 1000.04 GHz terahertz signal over a 42 km urban telecom fiber link, and achieved residual phase noise of -37 dBc/Hz at 1 Hz offset frequency, and the long-term frequency stability at 4000 s averaging time reaches 2 × 10−16. The factors that cause the performance limitations of the photonic terahertz wave distribution system are further analyzed.

Local photons

The classical free-space solutions of Maxwell’s equations for light propagation in one dimension include wave packets of any shape that travel at the speed of light. This includes highly-localised wave packets that remain localised at all times. Motivated by this observation, this paper builds on recent work by Southall et al. [J. Mod. Opt. 68, 647 (2021)] and shows that a local description of the quantised electromagnetic field, which supports such solutions and which must overcome several no-go theorems, is indeed possible. Starting from the assumption that the basic building blocks of photonic wave packets are so-called bosons localised in position (blips), we identify the relevant Schrödinger equation and construct Lorentz-covariant electric and magnetic field observables. In addition we show that our approach simplifies to the standard description of quantum electrodynamics when restricted to a subspace of states.