Symmetry Breaking in Quantum Systems
... The appearance of massless particles when a continuous symmetry is spontaneously broken is a general result, known as Goldstone's theorem. Goldstone's theorem states that for every spontaneously broken continuous symmetry, the theory must contain a massless particle. The massless elds that arise th ...
... The appearance of massless particles when a continuous symmetry is spontaneously broken is a general result, known as Goldstone's theorem. Goldstone's theorem states that for every spontaneously broken continuous symmetry, the theory must contain a massless particle. The massless elds that arise th ...
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... kept on at all times. In this way we can associate a modulation power spectrum with each spatial location in the sample. By measuring the power spectrum of the reradiated light as a function of modulation frequency. we can determine the object ...
... kept on at all times. In this way we can associate a modulation power spectrum with each spatial location in the sample. By measuring the power spectrum of the reradiated light as a function of modulation frequency. we can determine the object ...
Gold, copper, silver and aluminum nanoantennas to enhance
... Single molecules, nanocrystals and nanotubes are relevant light emitters for fundamental research and applications.1,2,3,4,5,6 However, many of these systems exhibit a low quantum yield and often photobleach. The latter issue can be solved by embedding the emitter into a matrix, such that reactive e ...
... Single molecules, nanocrystals and nanotubes are relevant light emitters for fundamental research and applications.1,2,3,4,5,6 However, many of these systems exhibit a low quantum yield and often photobleach. The latter issue can be solved by embedding the emitter into a matrix, such that reactive e ...
On distinguishability, orthogonality, and violations of the second law: contradictory assumptions, contrasting pieces of knowledge
... The interplay of orthogonality, distinguishability, thermodynamics, and multiplicity of observers is quite interesting; therefore we want to discuss and analyse it in varying depth, mainly with paedagogical purposes. The paper is divided into two main parts, reflecting two main perspectives. In the ...
... The interplay of orthogonality, distinguishability, thermodynamics, and multiplicity of observers is quite interesting; therefore we want to discuss and analyse it in varying depth, mainly with paedagogical purposes. The paper is divided into two main parts, reflecting two main perspectives. In the ...
QUANTUM COMPUTING: AN OVERVIEW
... Quantum computing and quantum information processing are emerging disciplines in which the principles of quantum physics are employed to store and process information. We use the classical digital technology at almost every moment in our lives: computers, mobile phones, mp3 players, just to name a f ...
... Quantum computing and quantum information processing are emerging disciplines in which the principles of quantum physics are employed to store and process information. We use the classical digital technology at almost every moment in our lives: computers, mobile phones, mp3 players, just to name a f ...
High-order impulse approximation for calculating pulsed-field recombination F. Robicheaux
... (p x ,p y ,p z ) is the electron’s momentum before the pulse. Depending on the strength of the half cycle pulse and the delay between the laser pulse and electric-field pulse, part of the continuum wave can be stopped; thus changing part of the outgoing continuum wave into a bound-state Rydberg wave ...
... (p x ,p y ,p z ) is the electron’s momentum before the pulse. Depending on the strength of the half cycle pulse and the delay between the laser pulse and electric-field pulse, part of the continuum wave can be stopped; thus changing part of the outgoing continuum wave into a bound-state Rydberg wave ...
Macroscopic quantum Schro¨dinger and Einstein–Podolsky–Rosen
... assumption of a form of reality (in this case Schrödinger’s ‘macroscopic reality’) gives an argument for the ‘completion’ (hidden variable interpretation) of quantum mechanics. 5.2 Direct macroscopic EPR paradox for entangled systems The bipartite entangled systems, where we satisfy conditions for ...
... assumption of a form of reality (in this case Schrödinger’s ‘macroscopic reality’) gives an argument for the ‘completion’ (hidden variable interpretation) of quantum mechanics. 5.2 Direct macroscopic EPR paradox for entangled systems The bipartite entangled systems, where we satisfy conditions for ...
Graviton physics - ScholarWorks@UMass Amherst
... of gravitons. Indeed, like photons, such particles are massless and subject to a gauge invariance, so that similar analytic results for graviton cross sections can be expected. Also, just as virtual photon exchange leads to a detailed understanding of electromagnetic interactions between charged sys ...
... of gravitons. Indeed, like photons, such particles are massless and subject to a gauge invariance, so that similar analytic results for graviton cross sections can be expected. Also, just as virtual photon exchange leads to a detailed understanding of electromagnetic interactions between charged sys ...
J JCAP01(2009)030 Covariant effective action for loop quantum cosmology `
... Friedman dynamics in the early universe. An approach in this direction is to find a renormalizable perturbative theory of quantum gravity which agrees with GR at low energies. This inspired modifications of the Einstein-Hilbert action via addition of terms involving higher curvature invariants and h ...
... Friedman dynamics in the early universe. An approach in this direction is to find a renormalizable perturbative theory of quantum gravity which agrees with GR at low energies. This inspired modifications of the Einstein-Hilbert action via addition of terms involving higher curvature invariants and h ...
Quantum key distribution
Quantum key distribution (QKD) uses quantum mechanics to guarantee secure communication. It enables two parties to produce a shared random secret key known only to them, which can then be used to encrypt and decrypt messages. It is often incorrectly called quantum cryptography, as it is the most well known example of the group of quantum cryptographic tasks.An important and unique property of quantum key distribution is the ability of the two communicating users to detect the presence of any third party trying to gain knowledge of the key. This results from a fundamental aspect of quantum mechanics: the process of measuring a quantum system in general disturbs the system. A third party trying to eavesdrop on the key must in some way measure it, thus introducing detectable anomalies. By using quantum superpositions or quantum entanglement and transmitting information in quantum states, a communication system can be implemented which detects eavesdropping. If the level of eavesdropping is below a certain threshold, a key can be produced that is guaranteed to be secure (i.e. the eavesdropper has no information about it), otherwise no secure key is possible and communication is aborted.The security of encryption that uses quantum key distribution relies on the foundations of quantum mechanics, in contrast to traditional public key cryptography which relies on the computational difficulty of certain mathematical functions, and cannot provide any indication of eavesdropping at any point in the communication process, or any mathematical proof as to the actual complexity of reversing the one-way functions used. QKD has provable security based on information theory, and forward secrecy.Quantum key distribution is only used to produce and distribute a key, not to transmit any message data. This key can then be used with any chosen encryption algorithm to encrypt (and decrypt) a message, which can then be transmitted over a standard communication channel. The algorithm most commonly associated with QKD is the one-time pad, as it is provably secure when used with a secret, random key. In real world situations, it is often also used with encryption using symmetric key algorithms like the Advanced Encryption Standard algorithm. In the case of QKD this comparison is based on the assumption of perfect single-photon sources and detectors, that cannot be easily implemented.