We construct a time-dependent double well potential as an exact spectral equivalent to the explicitly time-dependent negative quartic oscillator with a time-dependent mass term. Defining the unstable ...anharmonic oscillator Hamiltonian on a contour in the lower-half complex plane, the resulting time-dependent non-Hermitian Hamiltonian is first mapped by an exact solution of the time-dependent Dyson equation to a time-dependent Hermitian Hamiltonian defined on the real axis. When unitary transformed, scaled and Fourier transformed we obtain a time-dependent double well potential bounded from below. All transformations are carried out non-perturbatively so that all Hamiltonians in this process are spectrally exactly equivalent in the sense that they have identical instantaneous energy eigenvalue spectra.
•Time-dependent spectrally equivalent potentials are constructed.•Double wells are equivalent to time-dependent negative quartic oscillators.•We provide new analytical solutions to the time-dependent Dyson equation.
We extend our exploration of nonstandard continuum quantum field
theories in
2+1
2
+
1
dimensions to
3+1
3
+
1
dimensions. These theories exhibit exotic global symmetries, a peculiar
spectrum of ...charged states, unusual gauge symmetries, and surprising
dualities. Many of the systems we study have a known lattice
construction. In particular, one of them is a known gapless fracton
model. The novelty here is in their continuum field theory description.
In this paper, we focus on models with a global
U(1)
U
(
1
)
symmetry and in a followup paper we will study models with a global
\mathbb{Z}_N
ℤ
N
symmetry.
Quantum spin liquids Broholm, C; Cava, R J; Kivelson, S A ...
Science (American Association for the Advancement of Science),
01/2020, Letnik:
367, Številka:
6475
Journal Article
Recenzirano
Odprti dostop
Spin liquids are quantum phases of matter with a variety of unusual features arising from their topological character, including "fractionalization"-elementary excitations that behave as fractions of ...an electron. Although there is not yet universally accepted experimental evidence that establishes that any single material has a spin liquid ground state, in the past few years a number of materials have been shown to exhibit distinctive properties that are expected of a quantum spin liquid. Here, we review theoretical and experimental progress in this area.
Abstract
In this paper, we address a gap in the conventional interpretations of quantum mechanics, specifically the requirement for a more comprehensive description of particle and light phenomena. ...We introduce an alternative interpretation underpinned by the traditional mathematical framework of quantum mechanics, thus ensuring compatibility with established principles. Central to our proposition is the concept that particles and light fundamentally manifest as a ubiquitous wave field, each point of which is imbued with unique energy characteristics. This perspective provides a consistent resolution to the long-standing quantum measurement problem and offers a fresh lens through which to understand the intricacies of phenomena such as the double-slit experiment. Our proposed interpretational approach represents a crucial first step towards more comprehensive research, aiming to provide analytical proof and design experiments that verify this wave field interpretation.
One of the hallmarks of quantum physics is the generation of non-classical quantum states and superpositions, which has been demonstrated in several quantum systems, including ions, solid-state ...qubits and photons. However, only indirect demonstrations of non-classical states have been achieved in mechanical systems, despite the scientific appeal and technical utility of such a capability
, including in quantum sensing, computation and communication applications. This is due in part to the highly linear response of most mechanical systems, which makes quantum operations difficult, as well as their characteristically low frequencies, which hinder access to the quantum ground state
. Here we demonstrate full quantum control of the mechanical state of a macroscale mechanical resonator. We strongly couple a surface acoustic-wave
resonator to a superconducting qubit, using the qubit to control and measure quantum states in the mechanical resonator. We generate a non-classical superposition of the zero- and one-phonon Fock states and map this and other states using Wigner tomography
. Such precise, programmable quantum control is essential to a range of applications of surface acoustic waves in the quantum limit, including the coupling of disparate quantum systems
.
In this paper, we employ the emerging paradigm of physics-informed neural networks (PINNs) for the solution of representative inverse scattering problems in photonic metamaterials and nano-optics ...technologies. In particular, we successfully apply mesh-free PINNs to the difficult task of retrieving the effective permittivity parameters of a number of finite-size scattering systems that involve many interacting nanostructures as well as multi-component nanoparticles. Our methodology is fully validated by numerical simulations based on the finite element method (FEM). The development of physics-informed deep learning techniques for inverse scattering can enable the design of novel functional nanostructures and significantly broaden the design space of metamaterials by naturally accounting for radiation and finite-size effects beyond the limitations of traditional effective medium theories.
Nuclear quantum effects influence the structure and dynamics of hydrogen-bonded systems, such as water, which impacts their observed properties with widely varying magnitudes. This review highlights ...the recent significant developments in the experiment, theory, and simulation of nuclear quantum effects in water. Novel experimental techniques, such as deep inelastic neutron scattering, now provide a detailed view of the role of nuclear quantum effects in water’s properties. These have been combined with theoretical developments such as the introduction of the principle of competing quantum effects that allows the subtle interplay of water’s quantum effects and their manifestation in experimental observables to be explained. We discuss how this principle has recently been used to explain the apparent dichotomy in water’s isotope effects, which can range from very large to almost nonexistent depending on the property and conditions. We then review the latest major developments in simulation algorithms and theory that have enabled the efficient inclusion of nuclear quantum effects in molecular simulations, permitting their combination with on-the-fly evaluation of the potential energy surface using electronic structure theory. Finally, we identify current challenges and future opportunities in this area of research.
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