We start this paper with a historical survey of the Casimir effect, showing that its origin is re... more We start this paper with a historical survey of the Casimir effect, showing that its origin is related to experiments on colloidal chemistry. We present two methods of computing Casimir forces, namely: the global method introduced by Casimir, based on the idea of zero-point energy of the quantum electromagnetic field, and a local one, which requires the computation of the energy-momentum stress tensor of the corresponding field. As explicit examples, we calculate the (standard) Casimir forces between two parallel and perfectly conducting plates and discuss the more involved problem of a scalar field submitted to Robin boundary conditions at two parallel plates. A few comments are made about recent experiments that undoubtedly confirm the existence of this effect. Finally, we briefly discuss a few topics which are either elaborations of the Casimir effect or topics that are related in some way to this effect as, for example, the influence of a magnetic field on the Casimir effect of charged fields, magnetic properties of a confined vacuum and radiation reaction forces on non-relativistic moving boundaries.
Quantum Field Theory Under the Influence of External Conditions (QFEXT09), 2010
We consider a massless scalar field in 1+1 dimensions that satisfies a Robin boundary condition a... more We consider a massless scalar field in 1+1 dimensions that satisfies a Robin boundary condition at a non-relativistic moving boundary. Using the perturbative approach introduced by Ford and Vilenkin, we compute the total force on the moving boundary. In contrast to what happens for the Dirichlet and Neumann boundary conditions, in addition to a dissipative part, the force acquires also a dispersive one. Further, we also show that with an appropriate choice for the mechanical frequency of the moving boundary it is possible to turn off the vacuum dissipation almost completely.
We investigate the spontaneous emission rate of a two-level quantum emitter near a graphene-coate... more We investigate the spontaneous emission rate of a two-level quantum emitter near a graphene-coated substrate under the influence of an external magnetic field. We demonstrate that the application of the magnetic field can substantially increase or decrease the decay rate. We show that a suppression as large as 99% in the Purcell factor is achieved even for moderate magnetic fields. The emitter's lifetime is a discontinuous function of |B|, which is a direct consequence of the occurrence of discrete Landau levels in graphene. We demonstrate that, in the near-field regime, the magnetic field enables an unprecedented control of the decay pathways into which the photon/polariton can be emitted. Our findings strongly suggest that a magnetic field could act as an efficient agent for on-demand, active control of light-matter interactions in graphene at the quantum level.
Physical review D: Particles and fields, Jan 15, 1985
... Authors: Farina, Carlos; Vaidya, Arvind. Affiliation: AA(Instituto de Física, Universidade Fe... more ... Authors: Farina, Carlos; Vaidya, Arvind. Affiliation: AA(Instituto de Física, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundo, Rio de Janeiro, CEP. 21.941-Brazil), AB(Instituto de Física, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha ...
We consider the propagation of light in the QED vacuum between an unusual pair of parallel plates... more We consider the propagation of light in the QED vacuum between an unusual pair of parallel plates, namely: a perfectly Ž. Ž. conducting one e ™`and an infinitely permeable one m ™`. For weak fields and in the soft photon approximation we Ž show that the speed of light for propagation normal to the plates is smaller than its value in unbounded space in contrast to w Ž. Ž .
We compute the influence of boundary conditions on the Euler-Heisenberg effective Lagrangian scal... more We compute the influence of boundary conditions on the Euler-Heisenberg effective Lagrangian scalar QED scalar for the case of a pure magnetic field. The boundary conditions constrain the quantum scalar field to vanish on two parallel planes separeted by a distance a and the magnetic field is assumed to be constant, uniform and perpendicular to the planes. The effective Lagrangian is obtained using Schwinger's proper-time representation and exhibits new contributions generated by the boundary condition much
After briefly reviewing how the (proper-time) Schwinger's formula works for computing the Casimir... more After briefly reviewing how the (proper-time) Schwinger's formula works for computing the Casimir energy in the case of "scalar electrodynamics" where the boundary conditions are dictated by two perfectly conducting parallel plates with separation a in the Z-axis, we propose a slightly modification in the previous approach based on an analytical continuation method. As we will see, for the case at hand our formula does not need the use of Poisson summation to get a (renormalized) finite result.
We start this paper with a historical survey of the Casimir effect, showing that its origin is re... more We start this paper with a historical survey of the Casimir effect, showing that its origin is related to experiments on colloidal chemistry. We present two methods of computing Casimir forces, namely: the global method introduced by Casimir, based on the idea of zero-point energy of the quantum electromagnetic field, and a local one, which requires the computation of the energy-momentum stress tensor of the corresponding field. As explicit examples, we calculate the (standard) Casimir forces between two parallel and perfectly conducting plates and discuss the more involved problem of a scalar field submitted to Robin boundary conditions at two parallel plates. A few comments are made about recent experiments that undoubtedly confirm the existence of this effect. Finally, we briefly discuss a few topics which are either elaborations of the Casimir effect or topics that are related in some way to this effect as, for example, the influence of a magnetic field on the Casimir effect of charged fields, magnetic properties of a confined vacuum and radiation reaction forces on non-relativistic moving boundaries.
Quantum Field Theory Under the Influence of External Conditions (QFEXT09), 2010
We consider a massless scalar field in 1+1 dimensions that satisfies a Robin boundary condition a... more We consider a massless scalar field in 1+1 dimensions that satisfies a Robin boundary condition at a non-relativistic moving boundary. Using the perturbative approach introduced by Ford and Vilenkin, we compute the total force on the moving boundary. In contrast to what happens for the Dirichlet and Neumann boundary conditions, in addition to a dissipative part, the force acquires also a dispersive one. Further, we also show that with an appropriate choice for the mechanical frequency of the moving boundary it is possible to turn off the vacuum dissipation almost completely.
We investigate the spontaneous emission rate of a two-level quantum emitter near a graphene-coate... more We investigate the spontaneous emission rate of a two-level quantum emitter near a graphene-coated substrate under the influence of an external magnetic field. We demonstrate that the application of the magnetic field can substantially increase or decrease the decay rate. We show that a suppression as large as 99% in the Purcell factor is achieved even for moderate magnetic fields. The emitter's lifetime is a discontinuous function of |B|, which is a direct consequence of the occurrence of discrete Landau levels in graphene. We demonstrate that, in the near-field regime, the magnetic field enables an unprecedented control of the decay pathways into which the photon/polariton can be emitted. Our findings strongly suggest that a magnetic field could act as an efficient agent for on-demand, active control of light-matter interactions in graphene at the quantum level.
Physical review D: Particles and fields, Jan 15, 1985
... Authors: Farina, Carlos; Vaidya, Arvind. Affiliation: AA(Instituto de Física, Universidade Fe... more ... Authors: Farina, Carlos; Vaidya, Arvind. Affiliation: AA(Instituto de Física, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundo, Rio de Janeiro, CEP. 21.941-Brazil), AB(Instituto de Física, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha ...
We consider the propagation of light in the QED vacuum between an unusual pair of parallel plates... more We consider the propagation of light in the QED vacuum between an unusual pair of parallel plates, namely: a perfectly Ž. Ž. conducting one e ™`and an infinitely permeable one m ™`. For weak fields and in the soft photon approximation we Ž show that the speed of light for propagation normal to the plates is smaller than its value in unbounded space in contrast to w Ž. Ž .
We compute the influence of boundary conditions on the Euler-Heisenberg effective Lagrangian scal... more We compute the influence of boundary conditions on the Euler-Heisenberg effective Lagrangian scalar QED scalar for the case of a pure magnetic field. The boundary conditions constrain the quantum scalar field to vanish on two parallel planes separeted by a distance a and the magnetic field is assumed to be constant, uniform and perpendicular to the planes. The effective Lagrangian is obtained using Schwinger's proper-time representation and exhibits new contributions generated by the boundary condition much
After briefly reviewing how the (proper-time) Schwinger's formula works for computing the Casimir... more After briefly reviewing how the (proper-time) Schwinger's formula works for computing the Casimir energy in the case of "scalar electrodynamics" where the boundary conditions are dictated by two perfectly conducting parallel plates with separation a in the Z-axis, we propose a slightly modification in the previous approach based on an analytical continuation method. As we will see, for the case at hand our formula does not need the use of Poisson summation to get a (renormalized) finite result.
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