- TRENDS, Quantum Optics, Aggregation, Productivity, Weak Measurement, Quantum Theory, and 14 moreQuantum Cryptography, Nanophotonics, Quantum entanglement, Nonlinear Optics, Mathematics of Cryptography, Foundations of Physics, Philosophy of Quantum Mechanics, Quantum Information, Foundations of Quantum Mechanics, Quantum Computation, Quantum Dots, Quantum Mechanics, Laser Physics, and Physical sciencesedit
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The thermal photon statistics of the Jaynes-Cummings model are derived. The thermodynamics of the field-atom system in equilibrium is also studied.
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We apply a tomographic method we have recently proposed to the reconstruction of the full entangled quantum state for the cyclotron and spin degrees of freedom of a trapped electron. Our numerical simulations show that the entangled state... more
We apply a tomographic method we have recently proposed to the reconstruction of the full entangled quantum state for the cyclotron and spin degrees of freedom of a trapped electron. Our numerical simulations show that the entangled state is accurately reconstructed. -Pacs: 03.65.
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It is shown that a linear Fabry-Perot cavity with an oscillating end mirror can be used as a quantum nondemolition measurement device or as a quantum noise eater. For high quality factor of the mechanical oscillator and high mechanical... more
It is shown that a linear Fabry-Perot cavity with an oscillating end mirror can be used as a quantum nondemolition measurement device or as a quantum noise eater. For high quality factor of the mechanical oscillator and high mechanical frequency, the output quantum fluctuations of a monocromatic light beam can be significantly squeezed at a frequency very close to that of the impinging light. At lower mechanical frequency, by measuring the statistics of the mechanical momentum, the measurement of the photon number is obtained without the demolition of the quantum state of the light inside the cavity. The analysis is performed by taking into account the coupling of the system with the external world.
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We analyze the spectrum of squeezing of the beam reflected by a one-ended empty cavity, treating separately the two cases in which the input corresponds to a squeezed vacuum, or to squeezed beam with a mean value much larger than the... more
We analyze the spectrum of squeezing of the beam reflected by a one-ended empty cavity, treating separately the two cases in which the input corresponds to a squeezed vacuum, or to squeezed beam with a mean value much larger than the fluctuations. In the first case the fluctuation ellipse can be rotated at will by varying the cavity length. In
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SummaryThe main result of this paper is to exhibit a field-theoretical derivation of the so-called «linear model» for the equation of state of a scalar-field model, valid near the critical point. We introduce a suitable version of the... more
SummaryThe main result of this paper is to exhibit a field-theoretical derivation of the so-called «linear model» for the equation of state of a scalar-field model, valid near the critical point. We introduce a suitable version of the «skeleton expansion technique» that allows us to investigate the critical behaviour as the order parameter and the temperature approach the critical point, both for temperature above and below the critical temperature. We select the first term of such an expansion: the one-loop diagrams. As the dimensionality of the physical space is extended to four,i.e. in the so-called ε limit, we recover up to the first order in ε the results already known in the literature. We finally discuss the validity of results for any ε up to the physical three-dimensional space.RiassuntoIl risultato principale del lavoro è quello di presntare un approccio di teoria dei campi per l'equazione di stato di un campo scalare in prossimità del punto critico. Si introduce un'opportuna versione della tecnica dello «sviluppo scheletro» che permette di analizzare l'andamento critico quando sia il parametro d'ordine che la temperatura si avvicinano ai rispettivi valori al punto critico. Si studia ciò sia per temperature al disopra che al disotto di quella critica. Di tale sviluppo si seleziona il primo termine: il diagramma ad un'ansa. Se la dimensionalità dello spazio è estesa fino a quattro, nel cosidetto limite ε, si ritrovano i risultati al primo ordine dello sviluppo in ε già noti nella letteratura. Infine si discute la validità dei risultati nel caso fisico dello spazio a tre dimensioni.РезюмеОсновной результат этой работы представляет вывод с помощью методов теории поля так называемой «линейной модели» уравнения состояния для модели скалярного поля, которое справедливо вблизи критической точки. Мы вводим соответствующий вариант «техники скелетного разложения», который позволяет нам исследовать критическое човедение, когда параметр упорядоченности и температура приближаются к критической точке, причем, рассмотрение проводится для температур вяше и ниже критической температуры. Мы выбираем первый член такого разложения: диаграммы с одной петлей. Когда размерность физического пространства расширяется до петырех, т.е. в так называемом ε пределе мы возвращаемся с точностью до первого порядка, по ε к результатам уже известным в литературе. В заключение мы обсуждаем сч→аведливость результатов для произвольного ε.
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The q-deformation of a single quantized radiation mode interacting with a collection of two level atoms is introduced, analyzing its effects on the cooperative behavior of the system.
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We present a scheme for the experimental realization of a quantum phase gate acting on the polarization degree of freedom of traveling single photon wave-packets. The scheme exploits the giant Kerr nonlinearities that can be achieved in... more
We present a scheme for the experimental realization of a quantum phase gate acting on the polarization degree of freedom of traveling single photon wave-packets. The scheme exploits the giant Kerr nonlinearities that can be achieved in dense atomic media showing electromagnetically induced transparency, and it may be useful in a variety of quantum communication schemes
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We apply the quantum locking scheme recently proposed by Courty et al. [Phys. Rev. Lett. 90, 083601 (2003)] for the reduction of back action noise to the realistic case of a gravitational wave interferometer. We show that by applying an... more
We apply the quantum locking scheme recently proposed by Courty et al. [Phys. Rev. Lett. 90, 083601 (2003)] for the reduction of back action noise to the realistic case of a gravitational wave interferometer. We show that by applying an active control to each mirror of the interferometer it is possible to improve significatively its sensitivity by reducing the radiation pressure noise.
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A feedback model based on direct photodetection and micromaser-like atomic injection is proposed for the preservation of quantum coherence in a cavity. We show that in this way it is possible to slow down significantly the decoherence of... more
A feedback model based on direct photodetection and micromaser-like atomic injection is proposed for the preservation of quantum coherence in a cavity. We show that in this way it is possible to slow down significantly the decoherence of Schrodinger cat states.
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We consider an optical cavity made by two moving mirrors and driven by an intense classical laser field. We determine the steady state of he optomechanical system and show that two vibrational modes of the mirrors, with effective mass of... more
We consider an optical cavity made by two moving mirrors and driven by an intense classical laser field. We determine the steady state of he optomechanical system and show that two vibrational modes of the mirrors, with effective mass of the order of micrograms, can be entangled thanks to the effect of radiation pressure. The resulting entanglement is however quite fragile with respect to temperature.
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We show how collective vibrational modes of two distant mirrors of an optical Fabry–Perot cavity can be entangled by the light bouncing between them. Such an entanglement can be demonstrated even at the macroscopic level of vibrational... more
We show how collective vibrational modes of two distant mirrors of an optical Fabry–Perot cavity can be entangled by the light bouncing between them. Such an entanglement can be demonstrated even at the macroscopic level of vibrational modes with an effective mass of the order of milligrams.
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ABSTRACT A number of schemes for a quantum interface between light at different wavelengths have been demonstrated and very recently various solutions for interfacing optics and microwaves have been proposed. We describe here a reversible... more
ABSTRACT A number of schemes for a quantum interface between light at different wavelengths have been demonstrated and very recently various solutions for interfacing optics and microwaves have been proposed. We describe here a reversible quantum interface between optical and microwave photons based on a micro-mechanical resonator in a superconducting circuit, simultaneously interacting with an optical and a microwave cavity. When the cavities are appropriately driven, the mechanical resonator mediates an effective parametric amplifier interaction, entangling an optical signal and a microwave idler. Such continuous variable (CV) entanglement can be then exploited to implement CV teleportation. The optical output is mixed with an optical 'client' field in an unknown quantum state on a beam splitter at the transmitting site (Alice). The two outputs are then subject to homodyne detection and the classical measurement results communicated to the receiving site (Bob). Upon receipt of these results, Bob makes a conditional displacement of the microwave field, again using beam splitters and a coherent microwave source. The resulting state of the output microwave field is then prepared in the same quantum state as the optical input state. The process is entirely symmetric: the Alice and Bob roles can be exchanged and an unknown input microwave field can be teleported onto the optical output field at Alice, realising therefore a reversible quantum state transfer between fields at completely different wavelengths.