The Generalized Tavis—Cummings Model with Cavity Damping

In this Communication, we consider a generalised Tavis–Cummings model when the damping process is taken into account. We show that the quantum dynamics governed by a non-Hermitian Hamiltonian is exactly solvable using the Quantum Inverse Scattering Method, and the Algebraic Bethe Ansatz. The leakage of photons is described by a Lindblad-type master equation. The non-Hermitian Hamiltonian is diagonalised by state vectors, which are elementary symmetric functions parametrised by the solutions of the Bethe equations. The time evolution of the photon annihilation operator is defined via a corresponding determinant representation.

Gravitation Ever Since and Forever

This work presents a new approach to gravitation. Instead of seeing mass as a source of gravitation, the opposite is assumed here. Namely, gravitation has been there first and ever since. Masses were brought into the game later, following highly energetic interactions between electromagnetic fields (photons), with the gravitation field. These interactions resulted in photon annihilation and pair (or jets) production processes. Though pair production is forbidden kinematically in an empty space, itis allowed when the interaction of an incoming photon with gravitation field occurs. Quantum fluctuations in the gravitation field create very intense geometrical distortions in spacetime which in turn allows for photons to undergo momentum changes in favor of pair production processes.

Noncommutative photon-added squeezed vacuum states

Noncommutative optical squeezed vacuum states are constructed as eigenstates of an appropriate two-photon annihilation operator corresponding to the Biedenharn–Macfarlane [Formula: see text]-oscillator. We consider in details the role of noncommutativity parameter [Formula: see text] on the nonclassical behaviors including quadrature squeezing and sub-Poissonian statistics. Also, we construct the noncommutative photon-added squeezed vacuum states and consider their Hillery-type higher-order squeezing and single-mode noise band.

Vacuum source-field correlations and advanced waves in quantum optics

The solution to the wave equation as a Cauchy problem with prescribed fields at an initial timet=0is purely retarded. Similarly, in the quantum theory of radiation the specification of Heisenberg picture photon annihilation and creation operators at timet>0in terms of operators att=0automatically yields purely retarded source-fields. However, we show that two-time quantum correlations between the retarded source-fields of a stationary dipole and the quantum vacuum-field possess advanced wave-like contributions. Despite their advanced nature, these correlations are perfectly consistent with Einstein causality. It is shown that while they do not significantly contribute to photo-detection amplitudes in the vacuum state, they do effect the statistics of measurements involving the radiative force experienced by a point charge in the field of the dipole. Specifically, the dispersion in the charge's momentum is found to increase with time. This entails the possibility of obtaining direct experimental evidence for the existence of advanced waves in physical reality, and provides yet another signature of the quantum nature of the vacuum.