Truncated-cone–shaped cavities with microwaves resonating within them (emdrives) move slightly towards their narrow ends, in contradiction to standard physics. This effect has been predicted by a model called quantised inertia (MiHsC) which assumes that the inertia of the microwaves is caused by Unruh radiation, more of which is allowed at the wide end. Therefore, photons going towards the wide end gain inertia, and to conserve momentum the cavity must move towards its narrow end, as observed. A previous analysis with quantised inertia predicted a controversial photon acceleration, which is shown here to be unnecessary. The previous analysis also mispredicted the thrust in those emdrives with dielectrics. It is shown here that having a dielectric at one end of the cavity is equivalent to widening the cavity at that end, and when dielectrics are considered, then quantised inertia predicts these results as well as the others, except for Shawyer's first test where the thrust is predicted to be the right size but in the wrong direction. As a further test, quantised inertia predicts that an emdrive's thrust can be enhanced by using a dielectric at the wide end.

We study energy levels of two heteronuclear molecules moving in a spherically symmetric harmonic trap. A role of electric dipole interactions is compared and contrasted with our earlier results (O łdziejewski R. et al., EPL, 114 (2016) 46003) for two magnetic dipolar atoms. We stress the importance of a rotational energy with its value which is very high compared to the energy of a dipolar interaction. We show that dipolar forces do not play a significant role in the ground state of the system under typical experimental conditions. However, there exist excited states that exhibit anticrossings similar to the ones observed for magnetic dipoles.

Nonequilibrium states of closed quantum many-body systems defy a thermodynamic description. As a consequence, constraints such as the principle of equal a priori probabilities in the microcanonical ensemble can be relaxed, which can lead to quantum states with novel properties of genuine nonequilibrium nature. In turn, for the theoretical description it is in general not sufficient to understand nonequilibrium dynamics on the basis of the properties of the involved Hamiltonians. Instead it becomes important to characterize time-evolution operators, which adds time as an additional scale to the problem. In this perspective article we summarize recent progress in the field of dynamical quantum phase transitions, which are phase transitions in time with temporal nonanalyticities in matrix elements of the time-evolution operator. These transitions are not driven by an external control parameter, but rather occur due to sharp internal changes generated solely by unitary real-time dynamics. We discuss the obtained insights on general properties of dynamical quantum phase transitions, their physical interpretation, potential future research directions, as well as recent experimental observations.

Landauer's principle states that information erasure requires heat dissipation. While Landauer's original result focused on equilibrium memories, we here investigate the reset of information stored in a nonequilibrium state of a symmetric two-state memory. We derive a nonequilibrium generalization of the erasure principle and demonstrate that the corresponding bounds on heat and work may be reduced to zero. We further introduce reset protocols that harness energy and entropy of the initial preparation and so allow to reach these nonequilibrium bounds. We finally provide numerical simulations with realistic parameters of an optically levitated nanosphere memory that support these findings. Our results indicate that local dissipation-free information reset is possible away from equilibrium.

We find an expression for the Cabibbo angle from quark flavour generators of the first two generations. The flavour generators operate on the toroidal components in an intrinsic dynamics for colour degrees of freedom. The generators have led to parton distributions for u and d valence quarks of the proton that compare well with those derived from experiment. The present result for the cosine of the Cabibbo angle compares rather well with the experimentally established value for the up-down quark mixing element 0.97420+/−0.00021 of the Cabibbo-Kobayashi-Maskawa matrix.

We present a general formalism that allows for the computation of large-order renormalized expansions, effectively doubling the numerically attainable perturbation order of renormalized Feynman diagrams. We show that this formulation compares advantageously to the currently standard techniques due to its high efficiency, simplicity, and broad range of applicability. Our formalism permits to easily complement perturbation theory with non-perturbative information, which we illustrate by implementing expansions renormalized by the addition of a gap or the inclusion of Dynamical Mean-Field Theory. As a result, we present numerically exact results for the square-lattice hole-doped Fermi-Hubbard model in the low-temperature non-Fermi-liquid regime, relevant to study the pseudogap of cuprate superconductors, and show the momentum-dependent suppression of fermionic excitations in the antinodal region.

We explore a new type of domain wall structure in ultrathin films with perpendicular anisotropy, that is influenced by the Dzyaloshinskii-Moriya interaction due to the adjacent layers. This study is performed by numerical and analytical micromagnetics. We show that these walls can behave like Néel walls with very high stability, moving in stationary conditions at large velocities under large fields. We discuss the relevance of such walls, that we propose to call Dzyaloshinskii domain walls, for current-driven domain wall motion under the spin Hall effect.

We examine interaction states between baryons in U(3) configurations. Such interaction states may represent the meson mass spectrum above the pion triplet. Our configuration space is the Lie group U(3) with a Hamiltonian structure for baryons as stationary states. Mesonic states come about via an interaction potential. The Hamiltonian can be diagonalized by a Rayleigh-Ritz method resulting in matrix element integrals that can be solved analytically for the toroidal degrees of freedom by expanding on a suitable set of base functions. We compare calculated eigenvalues for indefinite parity states to observed unflavoured meson masses.

Lotka's seminal work ( Lotka A. J., Proc. Natl. Acad. Sci. U.S.A., 6 (1920) 410) “on certain rhythmic relations” is already one hundred years old, but the research activity about pattern formations due to cyclical dominance is more vibrant than ever. It is because non-transitive interactions have a paramount role on maintaining biodiversity and adequate human intervention into ecological systems requires a deeper understanding of the related dynamical processes. In this Perspective we overview different aspects of biodiversity, with focus on how it can be maintained based on mathematical modeling of the last years. We also briefly discuss the potential links to evolutionary game models of social systems, and finally, give an overview about potential prospects for future research.

We find a relation for the proton charge radius in closed form. The result 0.841235641(10) fm agrees with determinations from muonic hydrogen. Our relation is based on a mapping from an intrinsic configuration space for the proton to the observed size in laboratory experiments. The torus of the configuration space leads to periodic potentials in dynamical toroidal angles with the proton charge radius as a scale parameter in the mapping to laboratory space. The periodic potentials allow the introduction of Bloch phase factors which open for period doublings in the wave function. The opening of Bloch degrees of freedom is mediated by the Higgs mechanism. Thus, we find that pi times the proton charge radius equals twice the proton Compton wavelength.

Quantum secure direct communication enables a direct message exchange over a quantum channel without any key generation in advance. Here we present a feasible protocol for long-distance measurement-device–independent quantum secure direct communication. The secure distance is increased by using ancillary entangled photon-pair sources and relay nodes. Meanwhile, its security is independent from measurement devices, which eliminates the potential loophole for eavesdropping in the detection systems. Moreover, this protocol can be implemented with linear optical devices and single-photon detectors.

We present a detailed analysis of the length- and timescales needed to approach the critical region of MBL from the delocalised phase, studying both eigenstates and the time evolution of an initial state. For the eigenstates we show that in the delocalised region there is a single length, which is a function of disorder strength, controlling the finite-size flow. Small systems look localised, and only for larger systems do resonances develop which restore ergodicity in the form of the eigenstate thermalisation hypothesis. For the transport properties, we study the time necessary to transport a single spin across a domain wall, showing how this grows quickly with increasing disorder, and compare it with the Heisenberg time. For a sufficiently large system the Heisenberg time is always larger than the transport time, but for a smaller system this is not necessarily the case. We conclude that the properties of the MBL transition cannot be explored using the system sizes or times available to current numerical and experimental studies.

In this work, the three-component coupled nonlinear Schrödinger (tc-CNLS) equation is systemically investigated. By using the Darboux transformation, the new breather wave and rogue wave solutions of the tc-CNLS equation are constructed. These solutions exhibit breather waves and rogue waves on a multi-soliton background. Furthermore, the dynamic behaviors of these solutions are analyzed with some graphics. Our results can be of much importance in enriching and predicting rogue wave phenomena arising in nonlinear wave fields.

In a non-equilibrium many-body system, the quantum information dynamics between non-complementary regions is a crucial feature to understand the local relaxation towards statistical ensembles. Unfortunately, its characterization is a formidable task, as non-complementary parts are generally in a mixed state. We show that for integrable systems, this quantum information dynamics can be quantitatively understood within the quasiparticle picture for the entanglement spreading. Precisely, we provide an exact prediction for the time evolution of the logarithmic negativity after a quench. In the space-time scaling limit of long times and large subsystems, the negativity becomes proportional to the Rényi mutual information with Rényi index . We provide robust numerical evidence for the validity of our results for free-fermion and free-boson models, but our framework applies to any interacting integrable system.

We demonstrate that it is possible to implement a quantum perceptron with a sigmoid activation function as an efficient, reversible many-body unitary operation. When inserted in a neural network, the perceptron's response is parameterized by the potential exerted by other neurons. We prove that such a quantum neural network is a universal approximator of continuous functions, with at least the same power as classical neural networks. While engineering general perceptrons is a challenging control problem —also defined in this work— the ubiquitous sigmoid-response neuron can be implemented as a quasi-adiabatic passage with an Ising model. In this construct, the scaling of resources is favorable with respect to the total network size and is dominated by the number of layers. We expect that our sigmoid perceptron will have applications also in quantum sensing or variational estimation of many-body Hamiltonians.

We present a general formalism that allows for the computation of large-order renormalized expansions, effectively doubling the numerically attainable perturbation order of renormalized Feynman diagrams. We show that this formulation compares advantageously to the currently standard techniques due to its high efficiency, simplicity, and broad range of applicability. Our formalism permits to easily complement perturbation theory with non-perturbative information, which we illustrate by implementing expansions renormalized by the addition of a gap or the inclusion of Dynamical Mean-Field Theory. As a result, we present numerically exact results for the square-lattice hole-doped Fermi-Hubbard model in the low-temperature non-Fermi-liquid regime, relevant to study the pseudogap of cuprate superconductors, and show the momentum-dependent suppression of fermionic excitations in the antinodal region.

In this paper, we report the implementation of the method of optimal uncoupling and its effect in enhancing the stability of synchronization in certain coupled third-order chaotic systems. The clipping of phase space of the response system to a finite width having certain orientation about the coordinate axes representing the state variables of the response system insists that those state variables are coupled with their counterpart of the drive system. The stability of synchronization is studied through the master stability function (MSF). The optimal directions of implementing the clipping width to achieve stable synchronization is observed by studying the effectiveness of the clipping fraction and the sufficient range of orientation to identify the optimal directions is reported. The functional work steps for identifying the optimal directions are presented and the synchronization of the response system with the drive within the clipped region of phase space for different orientations of clipping width are studied. The stability of synchronization for different orientations of the clipping widths and the two-parameter bifurcation diagram indicating the negative valued MSF regions obtained for the optimal direction of clipping width are presented. The application of the method of optimal uncoupling in identifying the direction of the implication of the clipping width is discussed and the range of orientation over which the clipping width has to be varied is generalized.

Kelly's criterion is a betting strategy that maximizes the long-term growth rate, but which is known to be risky. Here, we find optimal betting strategies that gives the highest capital growth rate while keeping a certain low value of risky fluctuations. We then analyze the trade-off between the average and the fluctuations of the growth rate, in models of horse races, first for two horses then for an arbitrary number of horses, and for uncorrelated or correlated races. We find an analog of a phase transition with a coexistence between two optimal strategies, where one has risk and the other one does not. The above trade-off is also embodied in a general bound on the average growth rate, similar to thermodynamic uncertainty relations. We also prove mathematically the absence of other phase transitions between Kelly's point and the risk-free strategy.

We investigate the interaction between a topological insulator nanoparticle and a quantum dot in an impulse magnetic field. Since topological insulators are nonmagnetic, after the impulse has ended only the localised topological surface modes, which are quantised in terms of dipolar bosonic modes, couple dipolarly to the quantum dot. Hence, the hybrid system can be treated as a single bosonic mode interacting with a two-level system, where the coupling strength is quantised in terms of the magnetoelectric polarizability. We implement the interaction of the hybrid with the environment through the coupling with a continuum reservoir of radiative output modes and a reservoir of phonon modes. Using the method of Zubarev's Green functions, we derive an expression for the optical absorption spectrum of the system. We find the emergence of Fano resonances which are direct manifestations of the invariant of topological insulators. We present numerical results for a topological insulator nanosphere made of TlBiSe₂interacting with a CdSe quantum dot.

We analyze the phenomena of spontaneous symmetry breaking in quantum finance by using as a starting point the Black-Scholes (BS) and the Merton-Garman (MG) equations expressed in the Hamiltonian form. In this scenario the martingale condition (state) corresponds to the vacuum state which becomes degenerate when the symmetry of the system is spontaneously broken. We then analyze the broken symmetries of the system and we interpret from the perspective of financial markets the possible appearance of the Nambu-Goldstone bosons.

We study a system of two atomic quantum kicked rotors with hard-core interaction. This system shows different dynamical behavior depending on the value of the kick period. In particular, we find that for periods close to resonance, the system shows a crossover from quantum resonance to dynamical localization. We characterize this crossover by the analysis of momenta distribution and density probability function in the configuration space, and discuss the role of the hard-core interaction on the dynamical localization by comparing it to the free-bosons case. In particular we note that dynamical localization of the center of mass persists even in the presence of strong interaction among the atoms. Some experimental proposals are also discussed.

We develop an effective scheme for implementing error-insensitive population transfer in a three-level system (qutrit) by invariant-based shortcuts with optimized drivings. Based on the method of inverse engineering, target population transfers can be performed in a shortcut manner. Taking into account the deviation errors and then optimizing the coherent drivings, we can improve the target population transfers to be insensitive to deviations of frequency detuning or Rabi coupling. Particularly, with an appropriate choice of coherent drivings, our scheme could be insensitive to these two kinds of errors simultaneously. As one of the potential applications, our scheme may remove the control errors of quantum operations on superconducting artificial atoms. By combining shortcuts to adiabaticity with optimal control, the protocol could offer a promising avenue to explore fast and robust quantum information processing experimentally.

We consider a one-dimensional (1D) array of coupled quantum harmonic oscillators of arbitrary size in the presence of staggered losses. The dynamics of the system is analyzed thoroughly, through exact solutions in which exceptional points (EPs) are found to greatly impact the system dynamics. In particular, different dynamical regimes arise due to the progressive emergence of EPs varying the interaction strength, also allowing for single frequency emission of all array components. Signatures of these regimes are found in the decay dynamics of the system, in the transmission and fluctuation spectra, and in the emergence of frequency windows where resonant absorption and emission are strongly inhibited because of interference effects.

We assess the energy cost of shortcuts to adiabatic expansions or compressions of a harmonic oscillator, the power strokes of a quantum Otto engine. Difficulties to identify the cost stem from the interplay between different parts of the total system (the primary system —the particle— and the control system) and definitions of work (exclusive and inclusive). While attention is usually paid to the inclusive work of the microscopic primary system, we identify the energy cost as the exclusive work of the total system, which, for a clear-cut scale disparity between a microscopic primary system and a macroscopic control system, coincides with the exclusive work for the control system alone. We redefine the “engine efficiency” taking into account this cost. Our working horse model is an engine based on an ion in a Paul trap with power strokes designed via shortcuts to adiabaticity. Opposite to the paradigm of slow-cycle reversible engines with vanishing power and maximal efficiency, this fast-cycle engine increases the microscopic power at the price of a vanishing efficiency. The Paul trap fixes the gauge for the primary system, resulting in a counterintuitive evolution of its inclusive power and internal energy. Conditions for which inclusive power of the primary system and exclusive power control system are proportional are found.

This mini-review addresses a bedrock problem for the advance of phononics: the building of feasible and efficient thermal diodes. We revisit investigations in classical and quantum systems. For the classical anharmonic chains of oscillators, the most used model for the study of heat conduction in insulating solids, we recall the ubiquitous occurrence of thermal rectification in graded systems, and we show that the match between graded structures and long-range interactions is an efficient mechanism to increase the rectification factor. For the cases of genuine quantum models, we present the spin chains, such as the open XXZ model, as profitable systems for the occurrence of thermal rectification and other interesting related properties. In particular, we describe two cases of perfect diodes: one for the spin current, in a two-segmented XXZ model, and another one for the heat current in a simple quantum Ising model with long-range interactions. We believe that such results involving interesting rectification properties in simple models will stimulate more theoretical and experimental investigations on the subject.

Modular value of an observable of a pre- and postselected quantum system is a concept similar to weak value, but in contrast to describing only weak coupling, it can describe the coupling of any strength but only for qubit meters, so it may be used more widely in some scenarios. Besides, modular value has been proved to have advantages on measuring weak values of nonlocal joint observables and nonlocal entanglement states. In this paper, we extend the work of J. S. Lundeen and K. J. Reschb on connection between the measured values of multiparticle observables of a pre- and postselected quantum system and annihilation operator by modular value and give their relation. Based on the above, we propose a new method different from tomography to measure modular values, and we find that our annihilation operator measurement (AOM) method can significantly reduce the number of measurements from O(4 ⁿ ) to O(2 ⁿ ) compared with the original tomography method.

We examine interaction states between baryons in U(3) configurations. Such interaction states may represent the meson mass spectrum above the pion triplet. Our configuration space is the Lie group U(3) with a Hamiltonian structure for baryons as stationary states. Mesonic states come about via an interaction potential. The Hamiltonian can be diagonalized by a Rayleigh-Ritz method resulting in matrix element integrals that can be solved analytically for the toroidal degrees of freedom by expanding on a suitable set of base functions. We compare calculated eigenvalues for indefinite parity states to observed unflavoured meson masses.

The place and role of an Observer in quantum mechanics has been a subject of an ongoing debate since the theory's inception. Wigner brought this question to the fore in a celebrated scenario in which a super-Observer observes a Friend making a measurement. Here we briefly review why this “Wigner Friend scenario” has been taken to require the introduction of the Observer's consciousness, or alternatively to show the inconsistency of quantum measurement theory. We will argue that quantum theory can consistently leave observers outside its narrative, by making only minimal assumptions about how the information about the observed results is stored in material records.

When a wave is incident on a complex scattering medium, the transmitted intensity differs from the incident one due to extinction. In the absence of absorption, the extinguished power is equal to the total scattered power, a well-known conservation law termed the optical theorem. Here, we extend the case of a single incident wave to the situation of scattering and extinction by multiple incoming waves. The emerging generalized optical theorem has the exciting consequence that multiple incident waves show mutual extinction and mutual transparency, phenomena that do not exist in common forward scattering or self-extinction. Based on both exact calculations of realistic three-dimensional (3D) samples containing many (up to 10 ⁴) scatterers and on approximate Fraunhofer diffraction theory we make the striking observation that the total extinction of two incident waves is greatly enhanced, called mutual extinction, or greatly reduced, mutual transparency, by up to 100% of the usual single-beam extinction. In view of the surprisingly strong mutual extinction and transparency, we propose new experiments to observe mutual extinction and transparency, namely in two-beam experiments with either elastic and absorbing scatterers, in optical wavefront shaping, in dynamic light scattering, and we discuss possible applications.

We derive the ratio of dark energy to baryon matter content in the universe from a Higgs potential matching a description of baryon matter on an intrinsic configuration space. The match determines the Higgs mass and self-coupling parameters and introduces a constant term in the Higgs potential. The constant term is taken to give dark energy contributions from detained neutrons, both primordial and piled-up neutrons from nuclear processes in stars. This corresponds to the dark energy content increasing with time. The two contributions possibly give rise to the primordial inflation and the later accelerated recession, respectively. The ensuing inflation during nucleosynthesis may explain the primordial lithium-seven deficit relative to the standard Big Bang nucleosynthesis model predictions. From the observed helium and stellar metallicity contents, we get a dark energy to baryon matter ratio of 14.5(0.7) to compare with the observed value of 13.9(0.2).

We present a new, more nuanced understanding of non-linear effects in inverse Compton sources. Deleterious non-linear effects can arise even at low laser intensities, a regime previously viewed as linear. After laying out a survey of non-linear phenomena which degrade the effectiveness of inverse Compton sources, we discuss two powerful techniques designed to avoid these non-linearities. Starting with the known technique of non-linear longitudinal chirping of the laser pulse in the high laser field regime, we show that the simple stretching of the laser pulse, while keeping the energy constant, can significantly increase the spectral density of the scattered radiation in many operating regimes. Our numerical simulations show that combining these two techniques avoids detrimental non-linearities and improves the performance of inverse Compton sources over an order of magnitude.

In stochastic resonance, a periodically forced Brownian particle in a double-well potential jumps between minima at rare increments, the prediction of which poses a major theoretical challenge. Here, we use a path-integral method to find a precursor to these transitions by determining the most probable (or “optimal”) space-time path of a particle. We characterize the optimal path using a direct comparison principle between the Langevin and Hamiltonian dynamical descriptions, allowing us to express the jump condition in terms of the accumulation of noise around the stable periodic path. In consequence, as a system approaches a rare event these fluctuations approach one of the deterministic minimizers, thereby providing a precursor for predicting a stochastic transition. We demonstrate the method numerically, which allows us to determine whether a state is following a stable periodic path or will experience an incipient jump with a high probability. The vast range of systems that exhibit stochastic resonance behavior insures broad relevance of our framework, which allows one to extract precursor fluctuations from data.

This letter presents a magnetic target inversion method that does not vary with changes in the coordinate system and is based on the cross-product of the intermediate eigenvectors of any two points in the dipole field which is in the same/opposite direction as the magnetic moment vector. We used tensor geometric invariants to interpret this new physical property and obtain the unit magnetic moment vector. Using this, the unit vector of the measurement point-source displacement vector was derived. The distance between the measurement point and the source was obtained via the Frobenius norm of the gradient tensor matrix. Simulations verified that the proposed method is unaffected by attitudes and yields unique inversion results, and the results revealed that the inversion accuracy of the proposed method is high. The simulation results also show that conditional cosine and measurement noise have considerable influence on the inversion accuracy in the proposed method.

In 2015, the ALICE Collaboration reported the first measurement of an excess in the yield of at very low transverse momentum ( ) in the forward rapidity region (2.5 <  y < 4) in peripheral lead-lead (Pb-Pb) collisions at at the CERN LHC. The coherent photoproduction was proposed as the potential underlying physics mechanism. This is known to be the main production mechanism for low- production in ultra-peripheral collisions, which are dominated by electromagnetic interactions. However, the observation of a large effect in more central collisions that are dominated by the hadronic interactions was quite surprising. This article represents a proceeding contribution on the preliminary results from Pb-Pb collisions at shown in a poster during the National Congress of the French Physics Society in July 2019.

Hydrodynamic instabilities often cause spatio-temporal pattern formations and transitions between them. We investigate a model experimental system, a density oscillator, where the bifurcation from a resting state to an oscillatory state is triggered by the increase in the density difference of the two fluids. Our results show that the oscillation amplitude increases from zero and the period decreases above a critical density difference. The detailed data close to the bifurcation point provide a critical exponent consistent with the supercritical Hopf bifurcation.