Emily Adlam - Academia.edu (original) (raw)

Papers by Emily Adlam

Communications in Mathematical Physics, Mar 28, 2021

Communications in Mathematical Physics, Sep 10, 2015

It has previously been suggested that small subsystems of closed quantum systems thermalize under... more It has previously been suggested that small subsystems of closed quantum systems thermalize under some assumptions; however, this has been rigorously shown so far only for systems with very weak interaction between subsystems. In this work, we give rigorous analytic results on thermalization for translation-invariant quantum lattice systems with finite-range interaction of arbitrary strength, in all cases where there is a unique equilibrium state at the corresponding temperature. We clarify the physical picture by showing that subsystems relax towards the reduction of the global Gibbs state, not the local Gibbs state, if the initial state has close to maximal population entropy and certain non-degeneracy conditions on the spectrum are satisfied. Moreover, we show that almost all pure states with support on a small energy window are locally thermal in the sense of canonical typicality. We derive our results from a statement on equivalence of ensembles generalizing earlier results by Lima, and give numerical and analytic finite-size bounds, relating the Ising model to the finite de Finetti theorem. Furthermore, we prove that global energy eigenstates are locally close to diagonal in the local energy eigenbasis, which constitutes a part of the eigenstate thermalization hypothesis that is valid regardless of the integrability of the model. Contents I. Introduction II. Summary of the main results A. Canonical typicality B. Equivalence of ensembles C. Dynamical thermalization D. Finite-size estimates E. Towards eigenstate thermalization III. Proofs of the main results A. Equivalence of ensembles B. Canonical typicality C. Dynamical thermalization D. Finite-size estimates for systems without interaction E. Numerical results on finite-size behavior in one dimension F. Local diagonality of energy eigenstates IV. Conclusions

The British Journal for the Philosophy of Science

Foundations of Physics

Recently there has been a great deal of interest in tabletop experiments intended to exhibit the ... more Recently there has been a great deal of interest in tabletop experiments intended to exhibit the quantum nature of gravity by demonstrating that it can induce entanglement. In order to evaluate the significance of these experiments, we must determine if there is any interesting class of possibilities that will be convincingly ruled out if it turns out that gravity can indeed induce entanglement. In this article, we suggest that this result would rule out a class of quantum gravity models that we refer to as ψ-incomplete quantum gravity (PIQG)-i.e. models of the interaction between quantum mechanics and gravity in which gravity is coupled to non-quantum beables rather than quantum beables. This indicates that the results of the tabletop experiments can also be understood as providing new information about the correct interpretation of quantum mechanics. In particular, a major motivation for these experiments is the idea that they witness the existence of superpositions of spacetimes, and thus it should be emphasised that claims about the existence of spacetime superpositions are not interpretation-neutral. ψ-complete interpretations of quantum mechanics, like the Everett interpretation, almost universally tell us that spacetime superpositions are possible, whereas in ψ-incomplete, ψ-nonphysical interpretations it seems more natural to predict that spacetime superpositions are not possible. Meanwhile ψ-incomplete, ψ-supplemented interpretations present us with a more complex picture where we may or may not end up predicting that spacetime superpositions are possible, depending on the way in which the coupling between spacetime and matter is constructed. Thus roughly speaking, a positive result to the tabletop experiments should increase our confidence in ψ-complete interpretations, whilst a negative result should instead increase our confidence in ψ-incomplete interpretations. In section 1 we introduce PIQG models, and then in section 2 we make the reasoning more precise by presenting a set of inferences that may be made about the ontology of quantum mechanics based on the results of tabletop experiments. In section 3 we discuss some existing PIQG models and consider what more needs to be done to make these sorts of approaches more appealing. There are two competing paradigms for the interpretation of these experiments, which have been dubbed the 'Newtonian' paradigm and the 'tripartite' paradigm: here we largely work within the tripartite paradigm, because the tripartite view is specifically concerned with ontological aspects of the tabletop experiments and that makes it a suitable setting for enquiries about the ontology of quantum mechanics, but in section 4 we consider what conclusions can be drawn if one does not presuppose the tripartite view. Finally in section 5 we discuss a cosmological phenomenon which could be regarded as providing evidence for PIQG models.

The Ehlers-Pirani-Schild (EPS) constructive axiomatisation of general relativity, published in 19... more The Ehlers-Pirani-Schild (EPS) constructive axiomatisation of general relativity, published in 1972, purports to build up the kinematical structure of that theory from only axioms which have indubitable empirical content. It is, therefore, of profound significance both to the epistemology and to the metaphysics of spacetime theories. In this article, we consider extensions of the EPS axiomatisation towards quantum general relativity based upon quantum mechanical inputs (Part III). There are two companion papers, in which we provide a pedagogical walkthrough to the EPS axiomatisation (Part I), and discuss the significance of constructive approaches to spacetime structure more generally (Part II).

Henri Poincaré's work on mathematical features of the Lorentz transformations was an important pr... more Henri Poincaré's work on mathematical features of the Lorentz transformations was an important precursor to the development of special relativity. In this paper I compare the approaches taken by Poincaré and Einstein, aiming to come to an understanding of the philosophical ideas underlying their methods. In section (1) I assess Poincaré's contribution, concluding that although he inspired much of the mathematical formalism of special relativity, he cannot be credited with an overall conceptual grasp of the theory. In section (2) I investigate the origins of the two approaches, tracing differences to a disagreement about the appropriate direction for explanation in physics; I also discuss implications for modern controversies regarding explanation in the philosophy of special relativity. Finally, in section (3) I consider the links between Poincaré's philosophy and his science, arguing that apparent inconsistencies in his attitude to special relativity can be traced back to his acceptance of a 'convenience thesis' regarding conventions.

Physical Review A, 2016

The properties of quantum information in space-time can be investigated by studying operational t... more The properties of quantum information in space-time can be investigated by studying operational tasks. In one such task, summoning, an unknown quantum state is supplied at one point, and a call is made at another for it to be returned at a third. Hayden-May recently proved necessary and sufficient conditions for guaranteeing successful return of a summoned state for finite sets of call and return points when there is a guarantee of at most one summons. We prove necessary and sufficient conditions when there may be several possible summonses and complying with any one constitutes success. We show there is a "quantum paradox of choice" in summoning: the extra freedom in completing the task makes it strictly harder. This intriguing result has practical applications for distributed quantum computing and cryptography and also implications for our understanding of relativistic quantum information and its localization in space-time.

Communications in Mathematical Physics, 2015

Physical Review A, 2015

We examine the possibility of device-independent relativistic quantum bit commitment. We note the... more We examine the possibility of device-independent relativistic quantum bit commitment. We note the potential threat of location attacks, in which the behaviour of untrusted devices used in relativistic quantum cryptography depends on their space-time location. We describe relativistic quantum bit commitment schemes that are immune to these attacks, and show that these schemes offer device-independent security against hypothetical post-quantum adversaries subject only to the no-signalling principle. We compare a relativistic classical bit commitment scheme with similar features, and note some possible advantages of the quantum schemes.

International Journal of Quantum Information, 2015

We describe new unconditionally secure bit commitment schemes whose security is based on Minkowsk... more We describe new unconditionally secure bit commitment schemes whose security is based on Minkowski causality and the monogamy of quantum entanglement. We first describe an ideal scheme that is purely deterministic, in the sense that neither party needs to generate any secret randomness at any stage. We also describe a variant that allows the committer to proceed deterministically, requires only local randomness generation from the receiver, and allows the commitment to be verified in the neighborhood of the unveiling point. We show that these schemes still offer near-perfect security in the presence of losses and errors, which can be made perfect if the committer uses an extra single random secret bit. We discuss scenarios where these advantages are significant.

Studies in History and Philosophy of Science

We undertake a reconstruction of the epistemic significance of research on operational theories i... more We undertake a reconstruction of the epistemic significance of research on operational theories in quantum foundations. We suggest that the space of operational theories is analogous to the space of possible worlds employed in the possible world semantics for modal logic, so research of this sort can be understood as probing modal structure. Thus we argue that operational axiomatisations of quantum mechanics may be interpreted as a novel form of structural realism; we discuss the consequences of this interpretation for the philosophy of structural realism and the future of operational theories.

In recent years the quantum foundations community has seen increasing interest in the possibility... more In recent years the quantum foundations community has seen increasing interest in the possibility of using retrocausality as a route to rejecting the conclusions of Bell's theorem and restoring locality to quantum physics. On the other hand, it has also been argued that accepting nonlocality leads to a form of retrocausality. In this article we seek to elucidate the relationship between retrocausality and locality. We begin by providing a brief schema of the various ways in which violations of Bell's inequalities might lead us to consider some form of retrocausality. We then consider some possible motivations for using retrocausality to rescue locality, arguing that none of these motivations is adequate and that therefore there is no clear reason why we should prefer local retrocausal models to nonlocal retrocausal models. Next, we examine several different conceptions of retrocausality, concluding that `all-at-once' retrocausality is more coherent than the alternative d...

The Frontiers Collection, 2019