G. Megaloudis

Quantum electrodynamic charge space energy bands in singly connected superconducting weak links

In a weak-link constriction between two bulk superconductors it is well known that the condensed matter Hamiltonian exhibits periodicity in magnetic flux space. It is shown that a quantum electrodynamic treatment of the voltage across the weak link yields energy bands periodic in the space of Maxwell electric flux displacement charge.

The Josephson pendulum as a nonlinear capacitor

In the quantum electrodynamic circuit theory of weak link constrictions, the singly connected weak link exhibits energy bands in charge space. Here, it is shown that charge space energy bands arise also in the quantum mechanical treatment of a Josephson pendulum.

Quantum electrodynamic theory of voltage carrying states in a current biased Josephson weak link

The Feynman path integral formulation of the Josephson effect is applied to the problem of the influence of quantum electrodynamic fluxoid tunnelling on the characteristics of a current biased, singly connected, Josephson weak link. The well known Josephson voltage biased frequency effect, 4GwV=(2eV/h(cross)), has a natural duality extension to a current bias frequency effect omega I=( pi I/e).

Theory of quantum-electrodynamic flux tunneling in a superconducting ring with a Josephson weak link

SummaryPrevious work on the Josephson critical-current law and the flux-tunneling critical-voltage law (which used the Feynman path integral technique) is here extended in terms of the wave functions used in the quantum-electrodynamic circuit theory. The explicit wave function representations of the flux tunneling matrix elements are derived. The polarization charge matrix elements are determined by the dissipative features of the weak link and the flux tunneling is inhibited principally by the overlap integrals of the photon wave functions. It is shown that a strongly dissipative weak link has large-polarization-charge matrix elements which enhance flux tunneling. The physical picture of the tunneling event is the same from both the Feynman phase interference and the conventional wave function viewpoints.RiassuntoSi estende qui il precedente lavoro sulla legge della corrente critica di Josephson e sulla legge del voltaggio critico del tunneling di flusso (che usa la tecnica dell’integrale di cammino di Feynman), sulle basi di funzioni d’onda usate nella teoria quanto elettrodinamica del circuito. Si derivano rappresentazioni esplicite di funzioni d’onda degli elementi di matrice del tunnelling di flusso. Gli elementi di matrice della carica di polarizzazione sono determinati dai comportamenti dissipativi del collegamento debole e che il tunnelling di flusso è inibito soprattutto dalle integrali di sovrapposizione delle funzioni d’onda fotoniche. Si mostra che un accoppiamento debole fortemente dissipativo ha elementi di matrice con grande carica di polarizzazione che migliorano il tunnelling di flusso è lo stesso sia a partire dall’interferenza di fase di Feynman che dai punti di vista delle funzioni d’onda convenzionali.РезюмеВ этой работе развиваются результаты предыдущей работы (в которой использовалась техника фейнмановских интегралов по траекториям) для закона критического тока Джозефсона и закона критического напряжения туннельного эффекта на основе волновых функций, используемых в квантовой электродинамической теории цепей. Выводятся точные представления для матричных элементов туннельного потока через волновые функции. Матричные элементы поляризационного заряда определяются диссипативными особенностями слабой связи. Туннельный поток определяется, в основном, интегралами перекрытия волновых функций фотона. Показывается, что сильно диссипативная слабая связь имеет большие матричные элементы поляризационного заряда, которые усиливают туннельный поток. Физическая картина явления туннелирования оказывается одинаковой при анализе из фейнмановской фазовой интерференции и при обычном анализе с помощью волновых функций.

Gravitational wave dispersion in condensed matter systems

The complex index of gravitational wave refraction in condensed matter systems is related to the viscosity response function. Simple applications are discussed for gravitational wave propagation in fluids and crystals.

Physical kinetics of quantum electrodynamic (1/ω)-noise

Abstract The physical kinetics of soft photon emission in electronic quantum brownian motion is invoked to give a simple picture of the quantum electrodynamic sources of “(1/ω)-noise” in conducting systems.

Schwinger renormalization group equations of state in circuits with classical electrodynamic noise

SummaryWe discuss the effective noise temperatureT* of a low-temperature circuit in terms of the Schwinger action principle formulation of the quantum Brownian-motion problem, and in the limit ω≪kBT*/h. Within this formulation, we derive a simple classical noise renormalization group equation for the example of a ferroelectric capacitor. We also consider the problem of noise in a superconducting ring containing a Josephson weak link.RiassuntoSi discute la temperature effettiva di rumoreT* di un circuito a bassa temperatura in termini della formulazione del problema quantico dei moti browniani in base al principio di azione di Schwinger, e per il limite ω≪kBT*/h. Nell’àmbito di questa formulazione, si deriva una semplice equazione classica del gruppo di rinormalizzazione del rumore per l’esempio di una capacità ferroelettrica. Si considera anche il problema del rumore in un anello superconduttore che contiene un legame debole di Josephson.РезюмеМы обсуждаем эффективную температуру шумаT* для цепи при низкой температуре, используя швингеровскую формулировку принципа действия для квантовой проблемы броуновского движения, а также в пределе ω≪kBT*/h. В рамках этого формализма мы выводим простое классическое шумовое уравнение группы перенормировки для ферроэлектрической емкости. Мы также рассматриваем проблему шума в сверхпроводящем кольце, содержащем слабый контакт Дфозефсона.

Kinetics of soft-graviton emission in dilute gases

SummaryThe notion, due to Handel, that soft-graviton emission in macroscopic bodies has measurable consequences is discussed for dilute gases. The Feynman amplitudes for graviton emission are briefly indicated as they would enter into condensed-matter transitions for dense fluids.

General relativistic gravitational field effects on superfluid phase interference devices

In some recent experiments, it has been established that the Newtonian gravitational potential can influence the phase interference between alternative virtual paths taken by a quantum test particle. The authors consider theoretically the influence of general relativistic fields on the phase interference of superfluid flows.