arXiv subjects

Bob Coecke

Publications and source records attributed to Bob Coecke.

At least 145 records · Page 8Linked to original sources

arXiv2003

Physical Traces: Quantum vs. Classical Information Processing

Within the Geometry of Interaction (GoI) paradigm, we present a setting that enables qualitative differences between classical and quantum processes to be explored. The key construction is the physical interpretation/realization of the traced monoidal categories of finite-dimensional vector spaces with tensor product as monoidal structure and of finite sets and relations with Cartesian product as monoidal structure, both of them providing a so-called wave-style GoI. The developments in this paper reveal that envisioning state update due to quantum measurement as a process provides a powerful tool for developing high-level approaches to quantum information processing.

cs.CG↗

arXiv2003

Entropic Geometry from Logic

We produce a probabilistic space from logic, both classical and quantum, which is in addition partially ordered in such a way that entropy is monotone. In particular do we establish the following equation: Quantitative Probability = Logic + Partiality of Knowledge + Entropy. That is: 1. A finitary probability space Δ^n (=all probability measures on {1,...,n}) can be fully and faithfully represented by the pair consisting of the abstraction D^n (=the object up to isomorphism) of a partially ordered set (Δ^n,\sqsubseteq), and, Shannon entropy; 2. D^n itself can be obtained via a systematic purely order-theoretic procedure (which embodies introduction of partiality of knowledge) on an (algebraic) logic. This procedure applies to any poset A; D_A\cong(Δ^n,\sqsubseteq) when A is the n-element powerset and D_A\cong(Ω^n,\sqsubseteq), the domain of mixed quantum states, when A is the lattice of subspaces of a Hilbert space. (We refer to http://web.comlab.ox.ac.uk/oucl/publications/tr/rr-02-07.html for a domain-theoretic context providing the notions of approximation and content.)

quant-ph↗

arXiv2002

Logic of Dynamics & Dynamics of Logic; Some Paradigm Examples

This paper surveys some recent developments towards a dynamic quantum logic and outlines its explicite construction -- some analogies and contrasts with other logics of dynamics are indicated. Abstract: The development of ``(static) operational quantum logic" points out that classical boolean structures are too rigid to describe the actual and potential properties of quantum systems. On the other hand, an intuitionistic perspective on operational quantum logic, guides us in the direction of incorporating dynamics logically by reconsidering the primitive propositions required to describe the behavior of a quantum system, in particular in view of the emergent disjunctivity due to the non-determinism of quantum measurements. A further elaboration on "intuitionistic quantum logic" emerges into a "dynamic operational quantum logic", which allows us to express dynamic reasoning in the sense that we can capture how actual properties propagate, including their temporal causal structure, and provides a unified logical description of systems which evolve or which are submitted to measurements. This setting reveals that even static operational quantum logic bears a hidden dynamic ingredient in terms of what is called "the orthomodularity" of the lattice-structure. Focusing on the quantale semantics for dynamic operational quantum logic, we delineate some points of difference with the existing quantale semantics for (non)-commutative linear logic.

math.LO↗

arXiv2002

Forcing Discretization and Determination in Quantum History Theories

We present a formally deterministic representation for quantum history theories where we obtain the probabilistic structure via a discrete contextual variable: no continuous probabilities are as such involved at the primal level -- we conceive as a history theory any theory that deals with sequential quantum measurements but remains essentially a dichotomic propositional theory. A major part of the paper consists of a concise survey of arXiv: quant-ph/0008061 and quant-ph/0008062.

quant-ph↗

arXiv2002

Quantum Logic in Intuitionistic Perspective

In their seminal paper Birkhoff and von Neumann revealed the following dilemma: "... whereas for logicians the orthocomplementation properties of negation were the ones least able to withstand a critical analysis, the study of mechanics points to the distributive identities as the weakest link in the algebra of logic." In this paper we eliminate this dilemma, providing a way for maintaining both. Via the introduction of the "missing" disjunctions in the lattice of properties of a physical system while inheriting the meet as a conjunction we obtain a complete Heyting algebra of propositions on physical properties. In particular there is a bijective correspondence between property lattices and propositional lattices equipped with a so called operational resolution, an operation that exposes the properties on the level of the propositions. If the property lattice goes equipped with an orthocomplementation, then this bijective correspondence can be refined to one with propositional lattices equipped with an operational complementation, as such establishing the claim made above. Formally one rediscovers via physical and logical considerations as such respectively a specification and a refinement of the purely mathematical result by Bruns and Lakser (1970) on injective hulls of meet-semilattices. From our representation we can derive a truly intuitionistic functional implication on property lattices, as such confronting claims made in previous writings on the matter. We also make a detailed analysis of disjunctivity vs. distributivity and finitary vs. infinitary conjunctivity, we briefly review the Bruns-Lakser construction and indicate some questions which are left open.

math.LO↗

arXiv2002

Disjunctive Quantum Logic in Dynamic Perspective

In arXiv: math.LO/0011208 we proposed the {\sl intuitionistic or disjunctive representation of quantum logic}, i.e., a representation of the property lattice of physical systems as a complete Heyting algebra of logical propositions on these properties, where this complete Heyting algebra goes equipped with an additional operation, the {\sl operational resolution}, which identifies the properties within the logic of propositions. This representation has an important application ``towards dynamic quantum logic'', namely in describing the temporal indeterministic propagation of actual properties of physical systems. This paper can as such by conceived as an addendum to ``Quantum Logic in Intuitionistic Perspective'' that discusses spin-off and thus provides an additional motivation. We derive a quantaloidal semantics for dynamic disjunctive quantum logic and illustrate it for the particular case of a perfect (quantum) measurement.

math.LO↗

arXiv2001

The Sasaki Hook is not a [Static] Implicative Connective but Induces a Backward [in Time] Dynamic One that Assigns Causes

In this paper we argue that the Sasaki adjunction, which formally encodes the logicality that different authors tried to attach to the Sasaki hook as a `quantum implicative connective', has a fundamental dynamic nature and encodes the so-called `causal duality' (Coecke, Moore and Stubbe 2001; quant-ph/0009100) for the particular case of a quantum measurement with a projector as corresponding self-adjoint operator. In particular: The action of the Sasaki hook $(a\stackrel{S}{\to}-)$ for fixed antecedent $a$ assigns to some property ``the weakest cause before the measurement of actuality of that property after the measurement'', i.e. ${(a\stackrel{S}{\to}b)}$ is the weakest property that guarantees actuality of $b$ after performing the measurement represented by the projector that has the `subspace $a$' as eigenstates for eigenvalue 1, say, the measurement that `tests' $a$ . From this we conclude that the logicality attributable to quantum systems contains a fundamentally dynamic ingredient: Causal duality actually provides a new dynamic interpretation of orthomodularity. We also reconsider the status of the Sasaki hook within `dynamic (operational) quantum logic' (DOQL). We can derive two labeled dynamic hooks (forwardly and backwardly) that encode how quantum measurements act on properties. In an even more radical perspective one could say that the transition from either classical or constructive/intuitionistic logic to quantum logic entails besides the introduction of an additional unary connective `operational resolution' (Coecke 2001a; math.LO/0011208) the shift from a binary connective implication to a ternary connective where two of the arguments refer to qualities of the system and the third, the new one, to an obtained outcome (in a measurement).

quant-ph↗

arXiv2001

A mechanistic macroscopic physical entity with a three-dimensional Hilbert space description

It is sometimes stated that Gleason's theorem prevents the construction of hidden-variable models for quantum entities described in a more than two-dimensional Hilbert space. In this paper however we explicitly construct a classical (macroscopical) system that can be represented in a three-dimensional real Hilbert space, the probability structure appearing as the result of a lack of knowledge about the measurement context. We briefly discuss Gleason's theorem from this point of view.

quant-ph↗

arXiv2001

A (Classical) Representation for a Spin-S Entity as a compound system in R^3 consisting of 2S Individual Spin-1/2 Entities

We generalize the results of [B. Coecke, Helv. Phys. Acta 68, 396 (1995)] for the representation of coherent states of a spin-1 entity to spin-S entities with S>1 and to non-coherent spin states: through the introduction of 'hidden correlations' (see quant-ph/0105093) we introduce a representation for a spin-S entity as a compound system consisting of 2S 'individual' spin-1/2 entities, each of them represented by a 'proper state', and such that we are able to consider a measurement on the spin-S entity as a measurement on each of the individual spin-1/2 entities. If the spin-S entity is in a maximal spin state, the 2S individual spin-1/2 entities behave as a collection of indistinguishable but separated entities. If not so, we have to introduce the same kind of hidden correlations as required for a hidden correlation representation of a compound quantum systems described by a symmetrical superposition. Moreover, by applying the Majorana representation and Aerts' representation for a spin-1/2 entity, this hidden correlation representation yields a classical mechanistic representation of a spin-S entity in R^3.

quant-ph↗

arXiv2001

Structural Characterization of Compoundness

We recover the rays in the tensor product of Hilbert spaces within a larger class of so called `states of compoundness', structured as a complete lattice with the `state of separation' as its top element. At the base of the construction lies the assumption that the cause of actuality of a property of one of the (as individual considered) entities in the compound system can be actuality of a property of the other one.

quant-ph↗

arXiv2001

A Representation for Compound Quantum Systems as Individual Entities: Hard Acts of Creation and Hidden Correlations

We introduce an explicit definition for 'hidden correlations' on individual entities in a compound system: when one individual entity is measured, this induces a well-defined transition of the 'proper state' of the other individual entities. We prove that every compound quantum system described in the tensor product of a finite number of Hilbert spaces can be uniquely represented as a collection of individual(ized) (peudo-)entities between which there exist such hidden correlations. We investigate the significance of these hidden correlation representations within the so-called ``creation-discovery-approach'' and in particular their compatibility with the ``hidden measurement formalism''. This leads us to the introduction of the notions of 'soft' and 'hard' 'acts of creation' and to the observation that our approach can be seen as a theory of (pseudo-)individuals when compared to the standard quantum theory. (For a presentation of the ideas proposed in this paper within a quantum logical setting, yielding a structural theorem for the representation of a compound quantum system in terms of the Hilbert space tensor product, we refer to quant-ph/0008054.)

quant-ph↗

arXiv2001

A classification of classical representations for quantum-like systems

For general non-classical systems, we study the different classical representations that fulfill the specific context dependence imposed by the hidden measurement system formalism introduced in quant-ph/0008061. We show that the collection of non-equivalent representations has a poset structure. We also show that in general, there exists no 'smallest' representation, since this poset is not a semi-lattice. Then we study the possible representations of quantum-like measurement systems. For example, we show that there exists a classical representation of finite dimensional quantum mechanics with ${\Bbb N}$ as a set of states for the measurement context, and we build an explicit example of such a representation.

quant-ph↗

arXiv2001

Operational quantum logic: An overview

The term quantum logic has different connotations for different people, having been considered as everything from a metaphysical attack on classical reasoning to an exercise in abstract algebra. Our aim here is to give a uniform presentation of what we call operational quantum logic, highlighting both its concrete physical origins and its purely mathematical structure. To orient readers new to this subject, we shall recount some of the historical development of quantum logic, attempting to show how the physical and mathematical sides of the subject have influenced and enriched one another.

quant-ph↗

arXiv2001

Quantaloids Describing Causation and Propagation of Physical Properties

A general principle of `causal duality' for physical systems, lying at the base of representation theorems for both compound and evolving systems, is proved; formally it is encoded in a quantaloidal setting. Other particular examples of quantaloids and quantaloidal morphisms appear naturally within this setting; as in the case of causal duality, they originate from primitive physical reasonings on the lattices of properties of physical systems. Furthermore, an essentially dynamical operational foundation for studying physical systems is outlined; complementary as it is to the existing static operational foundation, it leads to the natural axiomatization of `causal duality' in operational quantum logic.

quant-ph↗

arXiv2000

Classical representations for quantum-like systems through an axiomatics for context dependence

We introduce a definition for a 'hidden measurement system', i.e., a physical entity for which there exist: (i) 'a set of non-contextual states of the entity under study' and (ii) 'a set of states of the measurement context', and which are such that all uncertainties are due to a lack of knowledge on the actual state of the measurement context. First we identify an explicit criterion that enables us to verify whether a given hidden measurement system is a representation of a given couple $\Si,{\cal E}$ consisting of a set of states $\Si$ and a set of measurements ${\cal E}$ ($=$ measurement system). Then we prove for every measurement system that there exists at least one representation as a hidden measurement system with $[0,1]$ as set of states of the measurement context. Thus, we can apply this definition of a hidden measurement system to impose an axiomatics for context dependence. We show that in this way we always find classical representations (hidden measurement representations) for general non-classical entities (e.g. quantum entities).

quant-ph↗

arXiv2000

State transitions as morphisms for complete lattices

We enlarge the hom-sets of categories of complete lattices by introducing `state transitions' as generalized morphisms. The obtained category will then be compared with a functorial quantaloidal enrichment and a contextual quantaloidal enrichment that uses a specific concretization in the category of sets and partially defined maps ($Parset$).

math.DS↗

arXiv2000

A logical description for perfect measurements

We reconsider the description for property transitions due to perfect measurements, viewing them as a special case of general transitions that are due to an externally imposed change. We propose a corresponding syntax involving operational quantum logic and a fragment of non-commutative linear logic.

quant-ph↗

arXiv2000

Operational Galois adjunctions

We present a detailed synthetic overview of the utilisation of categorical techniques in the study of order structures together with their applications in operational quantum theory. First, after reviewing the notion of residuation and its implementation at the level of quantaloids we consider some standard universal constructions and the extension of adjunctions to weak morphisms. Second, we present the categorical formulation of closure operators and introduce a hierarchy of contextual enrichments of the quantaloid of complete join lattices. Third, we briefly survey physical state-property duality and the categorical analysis of derived notions such as causal assignment and the propagation of properties.

quant-ph↗