ABSTRACT
In this paper, we present a systematic approach to building useful time-dependent effective Hamiltonians in molecular quantum electrodynamics. The method is based on considering part of the system as an open quantum system and choosing a convenient unitary transformation based on the evolution operator. We illustrate our formalism by obtaining four Hamiltonians, each suitable to a different class of applications. We show that we may treat several effects of molecular quantum electrodynamics with a direct first-order perturbation theory. In addition, our effective Hamiltonians shed light on interesting physical aspects that are not explicit when employing more standard approaches. As applications, we discuss three examples: two-photon spontaneous emission, resonance energy transfer, and dispersion interactions.
ABSTRACT
We studied the thermodynamic properties such as the entropy, heat (JQ), and work (JW) rates involved when an atom passes through a Ramsey zone, which consists of a mode field inside a low-quality factor cavity that behaves classically, promoting rotations on the atomic state. Focusing on the atom, we show that JW predominates when the atomic rotations are successful, maintaining its maximum purity as computed by the von Neumann entropy. Conversely, JQ stands out when the atomic state ceases to be pure due to its entanglement with the cavity mode. With this, we interpret the quantum-to-classical transition in light of the heat and work rates. Besides, we show that, for the cavity mode to work as a Ramsey zone (classical field), several photons (of the order of 106) need to cross the cavity, which explains its classical behavior, even when the inside average number of photons is of the order of unity.
ABSTRACT
We study the frictional drag between two graphene layers placed inside a cavity. We show that the drag has two contributions: the well-known Coulomb drag, and a novel photon-mediated drag. The latter arises from a cavity-mediated interaction in which the backscattering is not suppressed and the screening is relatively weak. As a result, the photon-mediated drag resistivity in the Fermi-liquid regime acquires corrections to the usual quadratic temperature dependence, has a slow decay as the interlayer separationdincreases, and depends on the carrier densitynasρDâ¼1/n2. Thus, whereas for smalldandnthe Coulomb drag dominates, as these parameters increase the drag transitions to a purely photon-mediated drag. The onset of this transition depends on the electromagnetic field enhancement inside the cavity.
ABSTRACT
In this paper, we investigate the physical basis behind the molecular biochirality from the computation of a parity violation energy difference (PVED) in enantiomers of organic molecules (e.g., amino acids, which occur as levogyrous-type in nature), by considering the influence of fundamental interactions beyond the standard model of elementary particles and interactions. Particularly, we study the role of a 4-D Chern-Simons theory at the origin of this PVED, the Carroll-Field-Jackiw electrodynamics, which violates both Lorentz and parity symmetries. Then, we consider terrestrial and Jovian scenarios where the influence of a modified (effective) magnetic field generated by the planets on the molecules is taken into account in the calculation of PVED. Besides this quantity, we also calculate the relative quantity excess of an enantiomer over the other in a thermal bath. Finally, we compare the obtained results with those ones from other models based on fundamental interactions.
ABSTRACT
Homeopathic medicines affect physical properties of matter which depend on the characteristic and the potency of the medicine1. These effects can be explained from two aspects: (a) classical and (b) quantum electrodynamical. Using three different sets of experiments where homeopathic medicines have affected the physical properties of matter, we have shown how the results can be interpreted from both these points of view. (AU)