179 research outputs found
Nonclassical Radiation from Thermal Cavities in the Ultrastrong Coupling Regime
Thermal or chaotic light sources emit radiation characterized by a slightly
enhanced probability of emitting photons in bunches, described by a zero-delay
second-order correlation function . Here we explore
photon-coincidence counting statistics of thermal cavities in the ultrastrong
coupling regime, where the atom-cavity coupling rate becomes comparable to the
cavity resonance frequency. We find that, depending on the system temperature
and coupling rate, thermal photons escaping the cavity can display very
different statistical behaviors, characterised by second-order correlation
functions approaching zero or greatly exceeding two.Comment: results on frequency resolved photon correlations added, to appear in
Phys. Rev. Let
Comprendere la fisica quantistica: breve introduzione per principianti
Quantum physics is one of the greatest scientific and cultural in human history. Much of modern technology and our understanding of physical reality are based on it. Quantum physics represented a real cultural revolution as it involves a behavior of particles that radically contradicts our way of understanding everyday reality and the assumptions on which all the previous physics was founded. Yet, after a century from its foundation, mainly due to the abstract and complex mathematical formalism on which it is based, it remains for the non-professionals and for the high school students something mysterious and bizarre. In this paper we illustrate a didactic approach, which is inspired by recent attempts to reformulate this theory on the basis of elementary physical principles. This approach has the advantage of not using the mathematical formalism of the Hibert spaces and of the Hermitian operators, and of obtaining in an intuitive and reasonable way the fundamental concepts of indeterminacy and entanglement. We hope this approach can contribute to a greater dissemination and understanding of this scientific and cultural heritage.La fisica quantistica, rappresenta una delle maggiori scientifiche e culturali nella storia umana. Gran parte della moderna tecnologia e della nostra comprensione della realtà fisica si basano su di essa. La fisica quantistica rappresentò una reale rivoluzione culturale in quanto prevede un comportamento delle particelle che contraddice radicalmente il nostro modo di comprendere la realtà quotidiana e i presupposti su cui è stata fondata tutta la fisica precedente. Eppure, a distanza di un secolo dalla sua fondazione, a causa principalmente del formalismo matematico astratto e complesso su cui si basa, rimane per i non addetti ai lavori e per gli studenti di liceo qualcosa di misterioso e bizzarro. In questo lavoro illustriamo un approccio didattico, che prende spunto da recenti tentativi di riformulare questa teoria sulla base di principi fisici elementari. Tale approccio ha il vantaggio di non utilizzare il formalismo matematico degli spazi di Hibert e degli operatori Hermitiani, e di ricavare in modo intuitivo e ragionevole i concetti fondamentali di indeterminazione ed entanglement. Ci auguriamo che questo approccio possa contribuire ad una maggiore diffusione e comprensione di questo patrimonio scientifico e culturale
Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film
We present scanning near-field images of surface plasmon modes around a
single elliptical nanohole in 88 nm thick Au film. We find that rotating
surface plasmon vortex modes carrying extrinsic orbital angular momentum can be
induced under linearly polarized illumination. The vortex modes are obtained
only when the incident polarization direction differs from one of the ellipse
axes. Such a direct observation of the vortex modes is possible thanks to the
ability of the SNOM technique to obtain information on both the amplitude and
the phase of the near field. The presence of the vortex mode is determined by
the rotational symmetry breaking of the system and it can be considered the
counterpart of the photonic spin Hall effect. Finite element method
calculations show that such a vorticity originates from the presence of nodal
points where the phase of the field is undefined, leading to a circulation of
the energy flow. The configuration producing vortex modes corresponds to a
nonzero total topological charge (+1)
All Optical Switch of Vacuum Rabi Oscillations: The Ultrafast Quantum Eraser
We study the all-optical time-control of the strong coupling between a single
cascade three-level quantum emitter and a microcavity. We find that only
specific arrival-times of the control pulses succeed in switching-off the Rabi
oscillations. Depending on the arrival times of control pulses, a variety of
exotic non-adiabatic cavity quantum electrodynamics effects can be observed. We
show that only control pulses with specific arrival times are able to suddenly
switch-off and -on first-order coherence of cavity photons, without affecting
their strong coupling population dynamics. Such behavior may be understood as a
manifestation of quantum complementarity
Quantum control and long-range quantum correlations in dynamical Casimir arrays
The recent observation of the dynamical Casimir effect in a modulated
superconducting waveguide, coronating thirty years of world-wide research,
empowered the quantum technology community with a powerful tool to create
entangled photons on-chip. In this work we show how, going beyond the single
waveguide paradigm using a scalable array, it is possible to create
multipartite nonclassical states, with the possibility to control the
long-range quantum correlations of the emitted photons. In particular, our
finite-temperature theory shows how maximally entangled states can be
engineered in a realistic setup. The results here presented open the way to new
kinds of quantum fluids of light, arising from modulated vacuum fluctuations in
linear systems
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