# Salvador Robles-PerezUniversity Carlos III de Madrid | UC3M · Department of Mathematics

Salvador Robles-Perez

PhD

## About

50

Publications

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511

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Introduction

Additional affiliations

September 2012 - December 2012

September 2005 - October 2011

## Publications

Publications (50)

We reviewed the canonical quantisation of the geometry of the spacetime in the cases of a simply and a non-simply connected manifold. In the former, we analysed the information contained in the solutions of the Wheeler–DeWitt equation and showed their interpretation in terms of the customary boundary conditions that are typically imposed on the sem...

Within the third quantisation formalism, we find solutions of the Wheeler-DeWitt in terms of two sets of modes that can be identified with the Hartle-Hawking's no boundary condition and with the Vilenkin's tunneling boundary condition, respectively. The two sets of modes are related by a Bogolyubov transformation so the no boundary vacuum state tur...

We review the canonical quantisation of the geometry of the spacetime in the cases of a simply and a non-simply connected manifold. In the former, we analyse the information contained in the solutions of the Wheeler-DeWitt equation and interpret them in terms of the customary boundary conditions that are typically imposed on the semiclassical wave...

Using the third quantization formalism we study the quantum entanglement of universes created in pairs within the framework of standard homogeneous and isotropic cosmology. In particular, we investigate entanglement quantities (entropy, temperature) around the maxima, minima and inflection points of the classical evolution. The novelty from previou...

Using the 3rd quantization formalism we study the quantum entanglement of universes created in pairs within the framework of standard homogeneous and isotropic cosmology. In particular, we investigate entanglement quantities (entropy, temperature) around maxima, minima and inflection points of the classical evolution. The novelty from previous work...

If one analyses the quantum creation of the universe, it turns out that the most natural way in which the universes can be created is in pairs of universes whose time flow is reversely related. It means that the matter that propagates in one of the universes can be seen, from the point of view of the other universe, as antimatter, and viceversa. Th...

The classical evolution of the universe can be seen as a parametrised worldline of the minisuperspace, with the time variable t being the parameter that parametrises the worldline. The time reversal symmetry of the field equations implies that for any positive oriented solution there can be a symmetric negative oriented one that, in terms of the sa...

We generalize former findings regarding quantum-gravitational corrections arising from a canonical quantization of a perturbed Friedmann-Lemaître-Robertson-Walker (FLRW) universe during inflation by considering an initial state for the scalar and tensor perturbations that generalizes the adiabatic vacuum state and allows us to consider the scenario...

There is a formal analogy between the evolution of the universe, when it is seen as a trajectory in the minisuperspace, and the worldline followed by a test particle in a curved spacetime. The analogy can be extended to the quantum realm, where the trajectories are transformed into wave packets that give us the probability of finding the universe o...

We generalize former findings regarding quantum-gravitational corrections arising from a canonical quantization of a perturbed FLRW universe during inflation by considering an initial state for the scalar and tensor perturbations that generalizes the adiabatic vacuum state and allows us to consider the scenario that the perturbation modes start the...

We study a toy model of a multiverse consisting of canonically quantized universes that interact with each other on a quantum level based on a field-theoretical formulation of the Wheeler-DeWitt equation. This interaction leads to the appearance of a pre-inflationary phase in the evolution of the individual universes. We analyze scalar perturbation...

A canonical quantisation of the coordinates of the spacetime within the general relativity theory is proposed. This quantisation will depend on the observer but it provides an interesting perspective on the problem of relating the non-relativistic and classical limits of a possible quantum gravity theory. In this sense, within this formalism, it is...

There is a formal analogy between the evolution of the universe, when this is seen as a trajectory in the minisuperspace, and the worldline followed by a test particle in a curved spacetime. The analogy can be extended to the quantum realm, where the trajectories are transformed into wave functions that give us the probabilities of finding the univ...

We study a toy model of a multiverse consisting of canonically quantized universes that interact with each other on a quantum level based on a field-theoretical formulation of the Wheeler-DeWitt equation. This interaction leads to the appearance of a pre-inflationary phase in the evolution of the individual universes. We analyze scalar perturbation...

The creation of universes in entangled pairs with opposite values of the momenta conjugated to the configuration variables of the minisuperspace would be favoured in quantum cosmology by the conservation of the total momentum, in a parallel way as particles are created in pairs with opposite values of their momenta in a quantum field theory. Then,...

The creation of universes in entangled pairs with opposite values of the momenta conjugated to the configuration variables of the minisuperspace would be favoured in quantum cosmology by the conservation of the total momentum, in a parallel way as particles are created in pairs with opposite values of their momenta in a quantum field theory. Then,...

We address the quantisation of a model that induces the Little Sibling of the Big Rip (LSBR) abrupt event, where the dark energy content is described by means of a phantom-like fluid or a phantom scalar field. The quantisation is done in the framework of the Wheeler–DeWitt (WDW) equation and imposing the DeWitt boundary condition; i.e., the wave fu...

Within the framework of the third quantization, we consider the possibility that an initially recollapsing baby universe can enter a stage of near de Sitter inflation by tunnelling through a Euclidean wormhole that connects the recollapsing and inflationary geometries. We present the solutions for the evolution of the scale factor in the Lorentzian...

We analyze a quantized toy model of a universe undergoing eternal inflation using a quantum-field-theoretical formulation of the Wheeler-DeWitt equation. This so-called third quantization method leads to the picture that the eternally inflating universe is converted to a multiverse in which sub-universes are created and exhibit a distinctive phase...

In this paper it is presented the model of a multiverse made up of universes which are created in entangled pairs that conserve the total momentum conjugated to the scale factor. For the background spacetime it is assumed a FRW metric with a scalar field with mass $m$ minimally coupled to gravity. For the fields that propagate in the entangled spac...

We present Euclidean wormhole solutions describing possible bridges within the multiverse. The study is carried out in the framework of the third quantization. The matter content is modelled through a scalar field which supports the existence of a whole collection of universes. The instanton solutions describe Euclidean solutions that connect baby...

In the multiverse, the universes can be created in entangled pairs with spacetimes that are both expanding in terms of the time variables experienced by internal observers in their particle physics experiments. The time variables of the two universes are related by an antipodal-like symmetry that might explain why there is no antimatter in our univ...

In this paper it is studied the cosmology of a homogeneous and isotropic spacetime endorsed with a conformally coupled massless scalar field. We find six different solutions of the Friedmann equation that represent six different types of universes, all of them are periodically distributed along the complex time axis. From a classical point of view,...

We apply the Lewis--Riesenfeld invariant method for the harmonic oscillator with time dependent mass and frequency to the modes of a charged scalar field that propagates in a curved, homogeneous and isotropic spacetime. We recover the Bunch-Davies vacuum in the case of a flat DeSitter spacetime, the equivalent one in the case of a closed DeSitter s...

The observability of the multiverse is at the very root of its physical significance as a scientific proposal. In this conference we present, within the third quantization formalism, an interacting scheme between the wave functions of different universes and analyze the effects of some particular values of the coupling function. One of the main con...

We study scenarios of parallel cyclic multiverses which allow for a different evolution of the physical constants, while having the same geometry. These universes are classically disconnected, but quantum-mechanically entangled. Applying the thermodynamics of entanglement, we calculate the temperature and the entropy of entanglement. It emerges tha...

We examine a new multiverse scenario in which the component universes
interact. We focus our attention to the process of "true" vacuum nucleation in
the false vacuum within one single element of the multiverse. It is shown that
the interactions lead to a collective behaviour that might lead, under specific
conditions, to a pre-inflationary phase an...

The creation of universes in entangled pairs may avoid the initial
singularity and it would have observable consequences in a large macroscopic
universe like ours, at least in principle. In this paper we describe the
creation of an entangled pair of universes from a double instanton, which
avoids the initial singularity, in the case of a homogeneou...

We consider a multiverse scenario made up of classically disconnected regions
of the space-time that are, nevertheless, in a quantum entangled state. The
addition of a scalar field enriches the model and allows us to treat both the
inflationary and the `oscillatory stage' of the universe on the same basis.
Imposing suitable boundary conditions on t...

We study the dynamics of quantum correlation of optical coherent-state
qubits affected by the environment. It consists in sending these states
via a decohering quantum channel. The states used as the support of the
encoding information are affected by an amplitude damping channel. The
quantum discord is one of type of quantum correlations between t...

The entropy and Mandel function as entanglement predictable of multipartite entangled coherent states are studied. The possibility of using these states as quantum channel to perform quantum teleportation is investigated. Quantum teleportation is achieved by using both even and odd entangled coherent states in the presence of environmental noise. T...

Inter-universal entanglement may even exist in a multiverse in which there is
no common space-time among the universes. In particular, the entanglement
between the expanding and contracting branches of the universe might have
observable consequences in the dynamical and thermodynamical properties of one
single branch, making therefore testable the...

The boundary conditions to be imposed on the quantum state of the whole
multiverse could be such that the universes would be created in entangled
pairs. Then, inter-universal entanglement would provide us with a vacuum energy
for each single universe that might be fitted with observational data, making
testable not only the multiverse proposal but...

Quantum information theory and the multiverse are two of the greatest
outcomes of the XX century physics. The consideration of entanglement between
the quantum states of two or more universes in a multiverse scenario provides
us with a completely new paradigm that opens the door to novel approaches for
traditionally unsolved problems in cosmology....

The third quantization formalism of quantum cosmology adds simplicity and
conceptual insight into the quantum description of the multiverse. Within such
a formalism, the existence of squeezed and entangled states raises the question
of whether the complementary principle of quantum mechanics has to be extended
to the quantum description of the whol...

We study some collective phenomena that may happen in a multiverse scenario.
First, it is posed an interaction scheme between universes whose evolution is
dominated by a cosmological constant. As a result of the interaction, the value
of the cosmological constant of one of the universes becomes very close to zero
at the expense of an increasing val...

In this paper it is presented the model of a multiverse made up of entangled
pairs of universes. The arrow of time obtained from the principles of
thermodynamics and the arrow of time given by the thermodynamics of
entanglement for single universes are analyzed. The latter requires that the
single universes expand once they have crossed the quantum...

We show that there exists a T-duality symmetry between two-dimensional warp drives and two dimensional Tolman-Hawking and Gidding-Strominger baby universes respectively correlated in pairs, so that the creation of warp drives is also equivalent to space-time squeezing. It has been also seen that the nucleation of warp drives entails a violation of...

In this paper it is shown that the quantum state of a multiverse made up of
classically disconnected regions of the space-time, whose dynamical evolution
is dominated by a homogeneous and isotropic fluid, is given by a squeezed
state. These are typical quantum states that have no classical counterpart and,
therefore, they allow us to analyze the vi...

In this paper we study the decoherence processes of the semiclassical
branches of an accelerated universe due to their interaction with a scalar
field with given mass. We use a third quantization formalism to analyze the
decoherence between two branches of a parent universe caused by their
interaction with the vaccum fluctuations of the space-time,...

A third quantization formalism is applied to a simplified multiverse
scenario. A well defined quantum state of the multiverse is obtained which
agrees with standard boundary condition proposals. These states are found to be
squeezed, and related to accelerating universes: they share similar properties
to those obtained previously by Grishchuk and S...

In this paper, we study the role of coherent states in the realm of quantum cosmology, both in a second-quantized single universe and in a third-quantized quantum multiverse. In particular, most emphasis will be paid to the quantum description of multiverses made up of accelerated universes. We have shown that the quantum states involved at a quant...

Using the known result that the nucleation of baby universes in correlated pairs is equivalent to spacetime squeezing, we show in this Letter that there exists a T-duality symmetry between two-dimensional warp drives, which are physically expressible as localized de Sitter little universes, and two-dimensional Tolman–Hawking and Gidding–Strominger...

In this paper we study the accretion of dark energy onto a black hole in the cases that dark energy is equipped with a positive cosmological constant and when the space-time is described by a Schwarzschild-de Sitter metric. It is shown that, if confronted with current observational data, the results derived when no cosmological constant is present...

In the realm of a quantum cosmological model for dark energy in which we have been able to construct a well-defined Hilbert space, a consistent coherent state representation has been formulated that may describe the quantum state of the universe and has a well-behaved semiclassical limit.

We review some of the well-known features of quantum cosmology, such as the factor ordering problem, the wave function and the density matrix, for a dark energy dominated universe, where analytical solutions can be obtained. For the particular case of the phantom universe, we suggest a quantum system in which the usual notion of locality (non-local...

We present cosmic solutions corresponding to universes filled with dark and phantom energy, all having a negative cosmological constant. All such solutions contain infinite singularities, successively and equally distributed along time, which can be either big bang/crunches or big rips singularities. Classically these solutions can be regarded as a...