A5013166618- Cosmology and Gravitation Theories
- Quantum Electrodynamics and Casimir Effect
- Black Holes and Theoretical Physics
- Quantum, superfluid, helium dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- Strong Light-Matter Interactions
- Pulsars and Gravitational Waves Research
- Mechanical and Optical Resonators
- Relativity and Gravitational Theory
- Experimental and Theoretical Physics Studies
- Biofield Effects and Biophysics
- Geophysics and Sensor Technology
- Advanced Fiber Laser Technologies
- Advanced Image and Video Retrieval Techniques
- Optical and Acousto-Optic Technologies
- Video Surveillance and Tracking Methods
- Quantum Mechanics and Applications
- Nonlinear Photonic Systems
- Fluid Dynamics and Turbulent Flows
- Astrophysical Phenomena and Observations
- Physics of Superconductivity and Magnetism
- Particle Accelerators and Free-Electron Lasers
- Advanced Differential Geometry Research
- Advanced Vision and Imaging
- Atomic and Subatomic Physics Research
King's College London
2023-2024
University College London
2024
University of London
2023-2024
Universidad de Londres
2024
University of British Columbia
2021-2024
Texas A&M University
2022-2024
University of Nottingham
2017-2022
Durham University
2020
Universidade Federal do ABC
2019
Abstract Gravity simulators 1 are laboratory systems in which small excitations such as sound 2 or surface waves 3,4 behave fields propagating on a curved spacetime geometry. The analogy between gravity and fluids requires vanishing viscosity 2–4 , feature naturally realized superfluids liquid helium cold atomic clouds 5–8 . Such have been successful verifying key predictions of quantum field theory 7–11 In particular, simulations rotating spacetimes indicative astrophysical black holes...
The late stages of the relaxation process a black hole are expected to depend only on its mass and angular momentum not details formation process. Inspired by recent analogue gravity experiments, which demonstrate that certain processes take place in gravitational hydrodynamical systems alike, we conduct an experiment search for quasinormal mode oscillations free surface vortex flow. Our results occurrence hint at ubiquity ringing nonequilibrium analog experiments.
Analogue models of gravity, particularly fluid mechanical analogues, have been very successful in mimicking the behavior fields around black holes. However, hydrodynamic holes are externally driven systems whose effective mass and angular momentum set by experimental parameters, and, as such, no appreciable internal backreaction is expected to take place. On contrary, we show using a rotating draining vortex flow that system finite size responds presence waves on timescales much longer than...
Quasinormal modes are a set of damped resonances that describe how an excited open system is driven back to equilibrium. In gravitational physics these characterize the ringdown perturbed black hole, e.g., following binary hole merger. A careful analysis spectrum reveals properties such as its angular momentum and mass. more complex systems, might depend on parameters hence allows us search for new physics. We present hydrodynamic analog rotating illustrates presence extra structure affects...
Abstract We investigate ultra slow-roll inflation with a seed black hole in de Sitter background. By numerically tracking transitions from to inflation, we find that quasi-normal mode solutions of the scalar field are excited following decay attractor, depending on mass hole. For small holes, picture is similar standard usual damping field; large hole, ringing modes dominate. It believed transition pure inflationary case enhances peak primordial power spectrum, thereby increasing likelihood...
Black-hole spectroscopy aims to infer physical properties of black holes by detecting the spectrum quasinormal modes (QNMs) they emit while settling toward equilibrium. Unlike normal modes, which are resonances energy-conserving systems, QNMs damped oscillations that arise when a system loses energy. The detection full is challenging due their rapid decay, limiting observations only longest-lived mode. Theoretical and numerical studies suggest environmental confinement surrounding plasma or...
Spectroscopy is a fundamental tool in science which consists studying the response of system as function frequency.Among its many applications Physics, Biology, Chemistry and other fields, possibility identifying objects structures through their emission spectra remarkable incredibly useful.In this paper we apply spectroscopy idea to numerically simulated hydrodynamical flow, with goal developing new, non-invasive flow measurement technique.Our focus lies on an irrotational draining vortex,...
We show that the dynamical instability of quantum vortices with more than a single unit circulation results from superradiant bound state inside vortex core. then reveal striking behavior system in nonlinear regime. Counter to expectation should produce well-separated vortices, evolves into corotating singularities orbiting within few healing lengths each other, undergoing modulations separation. During these modulations, kinetic energy is traded back and forth between sound waves vortical...
Multiply quantized vortices (MQVs) within single-component Bose-Einstein condensates are unstable and decay rapidly. We show that MQVs can be stabilized by adding a small number of atoms second species to the vortex cores, these remain in core as system evolves. A consequence stabilization is nearby corotating orbit opposite sense their individual rotations when enough present. This has implications concerning imaging vortices, well quantum turbulence nucleation two-component condensates,...
Vortices and black holes set the scene for many interesting dynamical processes in physics. Here, we study instability of quantized vortices rotational superradiance around rotating holes, illustrating process that same physics is at play these two seemingly disparate phenomena. We also compare vortex to hole bomb instability, which occurs massive scalar fields Kerr spacetime. Taking inspiration from analogy between modes hydrogen spectrum, compared with nuclear resonances involved...
Quasinormal modes (QNMs) are essential for understanding the stability and resonances of open systems, with increasing prominence in black hole physics. We present here first study QNMs optical potentials. show that solitons can support QNMs, deriving a soliton perturbation equation giving exact analytical expressions fiber solitons. discuss boundary conditions this intrinsically dispersive system identify novel signatures dispersion. From here, we discover new analogy holes describe regime...
Abstract Despite its amazing quantitative successes and contributions to revolutionary technologies, physics currently faces many unsolved mysteries ranging from the meaning of quantum mechanics nature dark energy that will determine future Universe. It is clearly prohibitive for general reader, even best informed physicists, follow vast number technical papers published in thousands specialized journals. For this reason, we have asked leading experts across most important areas summarise...
We investigate the evaporation process of a Kerr–de Sitter black hole with Unruh–Hawking-like vacuum state, which is realistic state modelling originating from gravitational collapse. also compute greybody factors for gravitons, photons, and conformal-coupling massless scalar particles by using analytic solutions Teukolsky equation in background. It turns out that cosmological constant quenches amplification factor it approaches to zero towards critical point where Nariai extremal limits...
Wave equations containing spatial derivatives which are higher than second order arise naturally in the context of condensed matter systems. The solutions such contain more two modes and consequently, range possible interactions between different is significantly enhanced compared to mode case. We develop a framework for analyzing based on classical turning points dispersion relation. then apply this scattering deep water gravity waves with draining bathtub vortex, system constitutes...
We extend the concept of Hawking-Moss, or up-tunnelling, transitions in early universe to include black hole seeds. The greatly enhances decay amplitude, however, order have physically consistent results, we need impose a new condition (automatically satisfied for original Hawking-Moss instanton) that cosmological horizon area should not increase during tunnelling. motivate this conjecture two ways. First, look at energetics process, using formalism extended thermodynamics; secondly,...
Astrophysical black holes are open systems which, when perturbed, radiate quasi-normal modes (QNMs) to infinity. By contrast, laboratory analogues necessarily finite-sized, presenting a potential obstacle exciting QNMs in the lab. In this study, we investigate how QNM spectrum of toy-model hole is modified system enclosed by partially reflecting wall. Counter expectation, demonstrate that not only persist finite-sized systems, but number accessible increases. Furthermore, show set-up can be...
Quantum vortices with more than a single circulation quantum are usually unstable and decay into clusters of smaller vortices. One way to prevent the is place vortex at center convergent (draining) fluid flow, which tends force together. It found that while primary splitting instability suppressed in this (and completely quenched for strong enough flows) secondary can emerge circular trapping geometries. This behavior related an rotating black holes when superradiantly amplified waves...
We investigate wave-vortex interaction emerging from an expanding compact vortex cluster in a two-dimensional Bose-Einstein condensate. adapt techniques developed for gravitational objects to derive the characteristic modes of perturbatively around effective flow field. demonstrate existence orbits or sound-rings, analogy light-rings, and compute spectrum out-of-equilibrium cluster. The obtained numerical simulations stochastic Gross-Pitaevskii equation exhibiting is excellent agreement with...
Motivated by recent experimental progress, we study scalar wave propagation over an imperfect draining vortex, which can serve as analogue for rotating and non-rotating extreme compact objects (ECOs). We encapsulate the absorbing properties of ECO means effective boundary located around horizon. The presence reflection at boundary, characterised a single parameter $\mathcal{K}$, allows existence bound states between vortex core angular momentum barrier. these leads to enhanced absorption...
Gravity simulators are laboratory systems where small excitations like sound or surface waves behave as fields propagating on a curved spacetime geometry. The analogy between gravity and fluids requires vanishing viscosity, feature naturally realised in superfluids liquid helium cold atomic clouds. Such have been successful verifying key predictions of quantum field theory spacetime. In particular, simulations rotating spacetimes indicative astrophysical black holes require the realisation...
Quantum vortices with more than a single circulation quantum are usually unstable and decay into clusters of smaller vortices. One way to prevent the is place vortex at centre convergent (draining) fluid flow, which tends force together. It found that whilst primary splitting instability suppressed in this (and completely quenched for strong enough flows) secondary can emerge circular trapping geometries. This behaviour related an rotating black holes when superradiantly amplified waves...
Draining vortices with a free surface are frequently employed as rotating black hole simulators, both in theory and experiments. However, most theoretical work is restricted to the idealized regime, where wave dispersion dissipation neglected. We investigate role of these effects on analog bomb, an instability resulting from rotational superradiant amplification confined systems. reveal that deep water capillary-gravity waves significantly modifies unstable mode eigenfrequencies, whereas...