More Like this

1. Classical radiation fields for scalar, electromagnetic, and gravitational waves with spacetime-symmetry breaking

   https://doi.org/10.1016/j.aop.2023.169582  

   Bailey, Quentin G; Gard, Alexander S; Nilsson, Nils A; Xu, Rui; Shao, Lijing (February 2024, Annals of Physics)

   An effective field theory framework is used to investigate some Lorentz-violating effects on the generation of electromagnetic and gravitational waves, complementing previous work on propagation. Specifically we find solutions to a modified, anisotropic wave equation, sourced by charge or fluid matter. We derive the radiation fields for scalars, classical electromagnetic radiation, and partial results for gravitational radiation. For gravitational waves, the results show longitudinal and breathing polarizations proportional to coefficients for spacetime-symmetry breaking. 

   more » « less
2. Black-hole powered quantum coherent amplifier

   https://doi.org/10.1038/s41534-024-00817-w  

   Misra, Avijit; Chattopadhyay, Pritam; Svidzinsky, Anatoly; Scully, Marlan O; Kurizki, Gershon (December 2024, npj Quantum Information)

   Abstract Atoms falling into a black hole (BH) through a cavity are shown to enable coherent amplification of light quanta powered by the BH-gravitational vacuum energy. This process can harness the BH energy towards useful purposes, such as propelling a spaceship trapped by the BH. The process can occur via transient amplification of a signal field by falling atoms that are partly excited by Hawking radiation reflected by an orbiting mirror. In the steady-state regime of thermally equilibrated atoms that weakly couple to the field, this amplifier constitutes a BH-powered quantum heat engine. The envisaged effects substantiate the thermodynamic approach to BH acceleration radiation. 

   more » « less
3. Laser cooling of antihydrogen atoms

   https://doi.org/10.1038/s41586-021-03289-6  

   Baker, C. J.; Bertsche, W.; Capra, A.; Carruth, C.; Cesar, C. L.; Charlton, M.; Christensen, A.; Collister, R.; Mathad, A. Cridland; Eriksson, S.; et al (April 2021, Nature)

   null (Ed.)

   Abstract The photon—the quantum excitation of the electromagnetic field—is massless but carries momentum. A photon can therefore exert a force on an object upon collision 1 . Slowing the translational motion of atoms and ions by application of such a force 2,3 , known as laser cooling, was first demonstrated 40 years ago 4,5 . It revolutionized atomic physics over the following decades 6–8 , and it is now a workhorse in many fields, including studies on quantum degenerate gases, quantum information, atomic clocks and tests of fundamental physics. However, this technique has not yet been applied to antimatter. Here we demonstrate laser cooling of antihydrogen 9 , the antimatter atom consisting of an antiproton and a positron. By exciting the 1S–2P transition in antihydrogen with pulsed, narrow-linewidth, Lyman-α laser radiation 10,11 , we Doppler-cool a sample of magnetically trapped antihydrogen. Although we apply laser cooling in only one dimension, the trap couples the longitudinal and transverse motions of the anti-atoms, leading to cooling in all three dimensions. We observe a reduction in the median transverse energy by more than an order of magnitude—with a substantial fraction of the anti-atoms attaining submicroelectronvolt transverse kinetic energies. We also report the observation of the laser-driven 1S–2S transition in samples of laser-cooled antihydrogen atoms. The observed spectral line is approximately four times narrower than that obtained without laser cooling. The demonstration of laser cooling and its immediate application has far-reaching implications for antimatter studies. A more localized, denser and colder sample of antihydrogen will drastically improve spectroscopic 11–13 and gravitational 14 studies of antihydrogen in ongoing experiments. Furthermore, the demonstrated ability to manipulate the motion of antimatter atoms by laser light will potentially provide ground-breaking opportunities for future experiments, such as anti-atomic fountains, anti-atom interferometry and the creation of antimatter molecules. 

   more » « less
4. Exploring black hole mimickers: Electromagnetic and gravitational signatures of AdS black shells

   https://doi.org/10.1103/PhysRevD.111.024007  

   Giri, Suvendu; Danielsson, Ulf; Lehner, Luis; Pretorius, Frans (January 2025, Physical Review D)

   We study electromagnetic and gravitational properties of anti–de Seitter (AdS) black shells (also referred to as AdS black bubbles)—a class of quantum gravity motivated black hole mimickers, that in the classical limit are described as ultracompact shells of matter. We find that their electromagnetic properties are remarkably similar to black holes. We then discuss the extent to which these objects are distinguishable from black holes, both for intrinsic interest within the black shell model, and as a guide for similar efforts in other subclasses of exotic compact objects (ECOs). We study photon rings and lensing band characteristics, relevant for very large baseline interferometry (VLBI) observations, as well as gravitational wave observables—quasinormal modes in the eikonal limit and the static tidal Love number for nonspinning shells—relevant for ongoing and upcoming gravitational wave observations. Published by the American Physical Society2025 

   more » « less
5. Entanglement-enhanced matter-wave interferometry in a high-finesse cavity

   https://doi.org/10.1038/s41586-022-05197-9  

   Greve, Graham P.; Luo, Chengyi; Wu, Baochen; Thompson, James K. (October 2022, Nature)

   Abstract An ensemble of atoms can operate as a quantum sensor by placing atoms in a superposition of two different states. Upon measurement of the sensor, each atom is individually projected into one of the two states. Creating quantum correlations between the atoms, that is entangling them, could lead to resolutions surpassing the standard quantum limit 1–3  set by projections of individual atoms. Large amounts of entanglement 4–6 involving the internal degrees of freedom of laser-cooled atomic ensembles 4–16 have been generated in collective cavity quantum-electrodynamics systems, in which many atoms simultaneously interact with a single optical cavity mode. Here we report a matter-wave interferometer in a cavity quantum-electrodynamics system of 700 atoms that are entangled in their external degrees of freedom. In our system, each individual atom falls freely under gravity and simultaneously traverses two paths through space while entangled with the other atoms. We demonstrate both quantum non-demolition measurements and cavity-mediated spin interactions for generating squeezed momentum states with directly observed sensitivity $$3\,.\,{4}_{-0.9}^{+1.1}$$ 3 . 4 − 0.9 + 1.1  dB and $$2\,.\,{5}_{-0.6}^{+0.6}$$ 2 . 5 − 0.6 + 0.6  dB below the standard quantum limit, respectively. We successfully inject an entangled state into a Mach–Zehnder light-pulse interferometer with directly observed sensitivity $$1\,.\,{7}_{-0.5}^{+0.5}$$ 1 . 7 − 0.5 + 0.5  dB below the standard quantum limit. The combination of particle delocalization and entanglement in our approach may influence developments of enhanced inertial sensors 17,18 , searches for new physics, particles and fields 19–23 , future advanced gravitational wave detectors 24,25 and accessing beyond mean-field quantum many-body physics 26–30 . 

   more » « less