Search results for "Decoherence"
showing 10 items of 182 documents
On CPT Symmetry: Cosmological, Quantum-Gravitational and Other Possible Violations and Their Phenomenology
2004
I discuss various ways in which CPT symmetry may be violated, and their phenomenology in current or immediate future experimental facilities, both terrestrial and astrophysical. Specifically, I discuss first violations of CPT symmetry due to the impossibility of defining a scattering matrix as a consequence of the existence of microscopic or macroscopic space-time boundaries, such as Planck-scale Black-Hole (event) horizons, or cosmological horizons due to the presence of a (positive) cosmological constant in the Universe. Second, I discuss CPT violation due to breaking of Lorentz symmetry, which may characterize certain approaches to quantum gravity, and third, I describe models of CPT non…
Probing Planck scale physics with IceCube
2005
Neutrino oscillations can be affected by decoherence induced e.g. by Planck scale suppressed interactions with the space-time foam predicted in some approaches to quantum gravity. We study the prospects for observing such effects at IceCube, using the likely flux of TeV antineutrinos from the Cygnus spiral arm. We formulate the statistical analysis for evaluating the sensitivity to quantum decoherence in the presence of the background from atmospheric neutrinos, as well as from plausible cosmic neutrino sources. We demonstrate that IceCube will improve the sensitivity to decoherence effects of ${\cal O}(E^2/M_{\rm Pl})$ by 17 orders of magnitude over present limits and, moreover, that it ca…
Quantum gravitational decoherence from fluctuating minimal length and deformation parameter at the Planck scale
2020
Schemes of gravitationally induced decoherence are being actively investigated as possible mechanisms for the quantum-to-classical transition. Here, we introduce a decoherence process due to quantum gravity effects. We assume a foamy quantum spacetime with a fluctuating minimal length coinciding on average with the Planck scale. Considering deformed canonical commutation relations with a fluctuating deformation parameter, we derive a Lindblad master equation that yields localization in energy space and decoherence times consistent with the currently available observational evidence. Compared to other schemes of gravitational decoherence, we find that the decoherence rate predicted by our mo…
Quantum transport and the phase space structure of the Wightman functions
2019
We study the phase space structure of exact quantum Wightman functions in spatially homogeneous, temporally varying systems. In addition to the usual mass shells, the Wightman functions display additional coherence shells around zero frequency $k_0=0$, which carry the information of the local quantum coherence of particle-antiparticle pairs. We find also other structures, which encode non-local correlations in time, and discuss their role and decoherence. We give a simple derivation of the cQPA formalism, a set of quantum transport equations, that can be used to study interacting systems including the local quantum coherence. We compute quantum currents created by a temporal change in a par…
Intrinsic CPT violation and decoherence for entangled neutral mesons
2005
We present a combined treatment of quantum-gravity-induced effects and intrinsic CPT violation in entangled neutral-Kaon states. Our analysis takes into consideration two types of effects: first, those associated with the loss of particle-antiparticle identity, as a result of the ill-defined nature of the CPT operator, and second, effects due to the non-unitary evolution of the Kaons in the space-time foam. By studying a variety of phi-factory observables, involving identical as well as general final states, we derive analytical expressions, to leading order in the associated CPT violating parameters, for double-decay rates and their time-integrated counterparts. Our analysis shows that the…
Decoherence in supernova neutrino transformations suppressed by deleptonization
2007
16 pages, 12 figures.-- PACS nrs.: 14.60.Pq; 97.60.Bw.-- ISI Article Identifier: 000251987300100.-- ArXiv pre-print available at: http://arxiv.org/abs/0706.2498
Optimal control of quantum superpositions in a bosonic Josephson junction
2012
We show how to optimally control the creation of quantum superpositions in a bosonic Josephson junction within the two-site Bose-Hubbard model framework. Both geometric and purely numerical optimal control approaches are used, the former providing a generalization of the proposal of Micheli et al [Phys. Rev. A 67, 013607 (2003)]. While this method is shown not to lead to significant improvements in terms of time of formation and fidelity of the superposition, a numerical optimal control approach appears more promising, as it allows to create an almost perfect superposition, within a time short compared to other existing protocols. We analyze the robustness of the optimal solution against at…
Molecular spin qubits based on lanthanide ions encapsulated in cubic polyoxopalladates: design criteria to enhance quantum coherence
2015
The family of cubic polyoxopalladates encapsulating lanthanide ions [LnPd12(AsPh)8O32]5− where Ln = Tb, Dy, Ho, Er and Tm, is magnetically characterised and theoretically described by the Radial Effective Charge (REC) model and a phenomenological crystal-field approach using the full-hamiltonian, in the SIMPRE and CONDON packages respectively. The lack of anisotropy generates an extraordinarily rich energy level structure at low temperatures, which allows us to study how such a structure is affected by lifting the strict cubic symmetry and/or by applying an external magnetic field. In particular, we will explore the possibility of using these cubic Ln complexes as spin-qubits. We will focus…
Optimized adiabatic passage with dephasing
2008
We study adiabatic population transfer with dephasing in two-level models driven by a chirped driving field. We show that the population transfer is maximized when the dynamics follows specific ellipses as trajectories in the parameter space. We determine the optimal parameters and estimate the losses in a closed form. These estimates show a similar robustness as for the standard lossless adiabatic processes with respect to variations of the parameters.
Role of dense matter in collective supernova neutrino transformations
2008
6 pages, 2 figures.-- PACS nrs.: 14.60.Pq; 97.60.Bw.-- ArXiv pre-print available at: http://arxiv.org/abs/0807.0659