289 citations · 1.2k across the 27 of their papers we have counts for
27 papers
Compositionality in quantum reference frame perspectives
Bruna Sahdo, Esteban Castro-Ruiz
Understanding a composite system through its constituents is a fundamental practice in physics. In the context of quantum reference frames (QRFs), however, combining the usual quan…
An Operational Resolution of the Third-Particle Paradox
Časlav Brukner, Esteban Castro-Ruiz, Marius Krumm
We give an operational resolution of the third-particle paradox, relevant in the theory of quantum reference frames. The apparent paradox is that a system which is irrelevant in on…
Quantum incompatibility of Born probabilities
Esteban Castro-Ruiz, Nathan Cohen, Luis C. Barbado +1
Quantum theory challenges the view that individual measurement outcomes are predefined and independent of the measurement context. Yet the quantum state itself -- the catalogue of…
Quantum limits of a space-time reference frame
Davide Mattei, Esteban Castro-Ruiz
We study the limitations for defining spatial and temporal intervals when the only available reference frame is a single composite quantum system, whose internal degrees of freedom…
The Perspectives of Non-Ideal Quantum Reference Frames
Sébastien Christophe Garmier, Ladina Hausmann, Esteban Castro-Ruiz
We define the perspective of any quantum reference frame (QRF) and construct reversible transformations between different perspectives. Our construction is based on two principles…
Interpreting quantum reference frame transformations through a simple example
Esteban Castro-Ruiz, Thomas D. Galley, Leon Loveridge
Quantum reference frame transformations have been proposed to provide a means by which to translate descriptions of quantum systems relative to each other. At present, there are se…
Measurement events relative to temporal quantum reference frames
Ladina Hausmann, Alexander Schmidhuber, Esteban Castro-Ruiz
The Page-Wootters formalism is a proposal for reconciling the background-dependent, quantum-mechanical notion of time with the background independence of general relativity. Howeve…
Quantum Reference Frames for Lorentz Symmetry
Luca Apadula, Esteban Castro-Ruiz, Časlav Brukner
Since their first introduction, Quantum Reference Frame (QRF) transformations have been extensively discussed, generalising the covariance of physical laws to the quantum domain. D…
Quantum conformal symmetries for spacetimes in superposition
Viktoria Kabel, Anne-Catherine de la Hamette, Esteban Castro-Ruiz +1
Without a complete theory of quantum gravity, the question of how quantum fields and quantum particles behave in a superposition of spacetimes seems beyond the reach of theoretical…
Quantum reference frames for an indefinite metric
Anne-Catherine de la Hamette, Viktoria Kabel, Esteban Castro-Ruiz +1
The current theories of quantum physics and general relativity on their own do not allow us to study situations in which the gravitational source is quantum. Here, we propose a str…
Relative subsystems and quantum reference frame transformations
Esteban Castro-Ruiz, Ognyan Oreshkov
Recently there has been much effort in developing a quantum generalisation of reference frame transformations. Despite important progress, a complete understanding of their princip…
Comment on "Revisiting dynamics of quantum causal structures --when can causal order evolve?''
Esteban Castro-Ruiz, Flaminia Giacomini, Časlav Brukner
In the last few years, there has been increasing interest in quantum processes with indefinite causal order. Process matrices are a convenient framework to study such processes. Re…
Unruh effect for detectors in superposition of accelerations
Luis C. Barbado, Esteban Castro-Ruiz, Luca Apadula +1
The Unruh effect is the phenomenon that accelerated observers detect particles even when inertial observers experience the vacuum state. In particular, uniformly accelerated observ…
Quantum Temporal Superposition: the case of QFT
Laura J. Henderson, Alessio Belenchia, Esteban Castro-Ruiz +4
Quantum field theory is completely characterized by the field correlations between spacetime points. In turn, some of these can be accessed by locally coupling to the field simple…
Generalized probability rules from a timeless formulation of Wigner's friend scenarios
Veronika Baumann, Flavio Del Santo, Alexander R. H. Smith +3
The quantum measurement problem can be regarded as the tension between the two alternative dynamics prescribed by quantum mechanics: the unitary evolution of the wave function and…
Quantum clocks and the temporal localisability of events in the presence of gravitating quantum systems
Esteban Castro-Ruiz, Flaminia Giacomini, Alessio Belenchia +1
The standard formulation of quantum theory relies on a fixed space-time metric determining the localisation and causal order of events. In general relativity, the metric is influen…
Information Content of the Gravitational Field of a Quantum Superposition
Alessio Belenchia, Robert M. Wald, Flaminia Giacomini +3
When a massive quantum body is put into a spatial superposition, it is of interest to consider the quantum aspects of the gravitational field sourced by the body. We argue that in…
Relativistic quantum reference frames: the operational meaning of spin
Flaminia Giacomini, Esteban Castro-Ruiz, Časlav Brukner
The spin is the prime example of a qubit. Encoding and decoding information in the spin qubit is operationally well defined through the Stern-Gerlach set-up in the non-relativistic…
A change of perspective: switching quantum reference frames via a perspective-neutral framework
Augustin Vanrietvelde, Philipp A Hoehn, Flaminia Giacomini +1
Treating reference frames fundamentally as quantum systems is inevitable in quantum gravity and also in quantum foundations once considering laboratories as physical systems. Both…
Quantum Superposition of Massive Objects and the Quantization of Gravity
Alessio Belenchia, Robert M. Wald, Flaminia Giacomini +3
We analyse a gedankenexperiment previously considered by Mari et al. that involves quantum superpositions of charged and/or massive bodies ("particles") under the control of the ob…
Quantum mechanics and the covariance of physical laws in quantum reference frames
Flaminia Giacomini, Esteban Castro-Ruiz, Časlav Brukner
In physics, every observation is made with respect to a frame of reference. Although reference frames are usually not considered as degrees of freedom, in all practical situations…
Dynamics of quantum causal structures
Esteban Castro-Ruiz, Flaminia Giacomini, Časlav Brukner
It was recently suggested that causal structures are both dynamical, because of general relativity, and indefinite, due to quantum theory. The process matrix formalism furnishes a…
Indefinite causal structures for continuous-variable systems
Flaminia Giacomini, Esteban Castro-Ruiz, Časlav Brukner
In all our well-established theories, it is assumed that events are embedded in a global causal structure such that, for every pair of events, the causal order between them is alwa…
Lorentz transformations for massive two-particle systems: entanglement change and invariant subspaces
Esteban Castro-Ruiz, Eduardo Nahmad-Achar
Lorentz boosts on particles with spin and momentum degrees of freedom induce momentum-dependent rotations. Since, in general, different particles have different momenta, the transf…