arXiv subjects

Selman Ipek

Publications and source records attributed to Selman Ipek.

16 recordsLinked to original sources

arXiv2026

Extremal simplicial distributions on cycle scenarios with arbitrary outcomes

Cycle scenarios are a significant class of contextuality scenarios, with the Clauser-Horne-Shimony-Holt (CHSH) scenario being a notable example. While binary outcome measurements in these scenarios are well understood, the generalization to arbitrary outcomes remains less explored, except in specific cases. In this work, we employ homotopical methods in the framework of simplicial distributions to characterize all contextual vertices of the non-signaling polytope corresponding to cycle scenarios with arbitrary outcomes. Additionally, our techniques utilize the bundle perspective on contextuality and the decomposition of measurement spaces. This enables us to extend beyond scenarios formed by gluing cycle scenarios and describe contextual extremal simplicial distributions in these generalized contexts.

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arXiv2025

Double categories for adaptive quantum computation

Quantum computation admits several models that emphasize different computational primitives and forms of classical control. We develop a unified double categorical framework for describing these models and the conversions between them. The syntax is provided by double port graphs, whose horizontal wires carry quantum information and whose vertical wires carry classical information and control. For each set of port labels, these graphs form a double category, and this construction is functorial in the label set. The semantics is given by the one-object double category of adaptive instruments. Its associated horizontal and vertical monoidal categories recover, respectively, quantum channels and stochastic maps. An assignment of an adaptive instrument to each primitive label therefore extends canonically to a double functor on labeled double port graphs, providing their computational semantics. We apply this framework to prominent models of quantum computation, including the circuit model, measurement-based quantum computation, quantum computation with magic states, and measurement-based Pauli computation. Gadget constructions from quantum computing that implement conversions between these models become double functors. Finally, we show that the interaction between quantum operations and affine classical control in measurement-based Pauli computation realizes every Boolean function in the vertical direction, thereby providing the non-affine classical operations required for its simulation of the circuit model.

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arXiv2025

Phase space tableau simulation for quantum computation

We introduce a novel tableau-based classical simulation method for quantum computation, formulated within the phase space framework of the extended stabilizer theory of closed non-contextual operators. This method enables the efficient classical simulation of a broader class of quantum circuits beyond the stabilizer formalism. We implement the simulator and benchmark its performance on basic quantum algorithms, including the hidden shift and Deutsch--Jozsa algorithms.

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arXiv2024

Classical simulation of universal measurement-based quantum computation using multipartite Bell scenarios

We introduce a new classical simulation algorithm based on non-signaling polytopes of multipartite Bell scenarios, capable of simulating universal measurement-based quantum computation with single-qubit Pauli measurements. In our model, the simultaneous presence of non-stabilizerness and entanglement is necessary for quantum speedup. The region of quantum states that can be efficiently simulated includes the Bell polytope and extends beyond what is currently achievable by sampling algorithms based on phase space methods.

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arXiv2023

The degenerate vertices of the $2$-qubit $Λ$-polytope and their update rules

Recently, a class of objects, known as $Λ$-polytopes, were introduced for classically simulating universal quantum computation with magic states. In $Λ$-simulation, the probabilistic update of $Λ$ vertices under Pauli measurement yields dynamics consistent with quantum mechanics. Thus, an important open problem in the study of $Λ$-polytopes is characterizing its vertices and determining their update rules. In this paper, we obtain and describe the update of all degenerate vertices of $Λ_{2}$, the $2$-qubit $Λ$ polytope. Our approach exploits the fact that $Λ_{2}$ projects to a well-understood polytope $\text{MP}$ consisting of distributions on the Mermin square scenario. More precisely, we study the ``classical" polytope $\overline{\text{MP}}$, which is $\text{MP}$ intersected by the polytope defined by a set of Clauser-Horne-Shimony-Holt (CHSH) inequalities. Owing to a duality between CHSH inequalities and vertices of $\text{MP}$ we utilize a streamlined version of the double-description method for vertex enumeration to obtain certain vertices of $\overline{\text{MP}}$.

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arXiv2023

Topological methods for studying contextuality: $N$-cycle scenarios and beyond

Simplicial distributions are combinatorial models describing distributions on spaces of measurements and outcomes that generalize non-signaling distributions on contextuality scenarios. This paper studies simplicial distributions on $2$-dimensional measurement spaces by introducing new topological methods. Two key ingredients are a geometric interpretation of Fourier--Motzkin elimination and a technique based on collapsing of measurement spaces. Using the first one, we provide a new proof of Fine's theorem characterizing non-contextual distributions on $N$-cycle scenarios. Our approach goes beyond these scenarios and can describe non-contextual distributions on scenarios obtained by gluing cycle scenarios of various sizes. The second technique is used for detecting contextual vertices and deriving new Bell inequalities. Combined with these methods, we explore a monoid structure on simplicial distributions.

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arXiv2023

Simplicial quantum contextuality

We introduce a new framework for contextuality based on simplicial sets, combinatorial models of topological spaces that play a prominent role in modern homotopy theory. Our approach extends measurement scenarios to consist of spaces (rather than sets) of measurements and outcomes, and thereby generalizes nonsignaling distributions to simplicial distributions, which are distributions on spaces modeled by simplicial sets. Using this formalism we present a topologically inspired new proof of Fine's theorem for characterizing noncontextuality in Bell scenarios. Strong contextuality is generalized suitably for simplicial distributions, allowing us to define cohomological witnesses that extend the earlier topological constructions restricted to algebraic relations among quantum observables to the level of probability distributions. Foundational theorems of quantum theory such as the Gleason's theorem and Kochen-Specker theorem can be expressed naturally within this new language.

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arXiv2022

Mermin polytopes in quantum computation and foundations

Mermin square scenario provides a simple proof for state-independent contextuality. In this paper, we study polytopes $\text{MP}_β$ obtained from the Mermin scenario, parametrized by a function $β$ on the set of contexts. Up to combinatorial isomorphism, there are two types of polytopes $\text{MP}_0$ and $\text{MP}_1$ depending on the parity of $β$. Our main result is the classification of the vertices of these two polytopes. In addition, we describe the graph associated with the polytopes. All the vertices of $\text{MP}_0$ turn out to be deterministic. This result provides a new topological proof of a celebrated result of Fine characterizing noncontextual distributions on the CHSH scenario. $\text{MP}_1$ can be seen as a nonlocal toy version of $Λ$-polytopes, a class of polytopes introduced for the simulation of universal quantum computation. In the $2$-qubit case, we provide a decomposition of the $Λ$-polytope using $\text{MP}_1$, whose vertices are classified, and the nonsignaling polytope of the $(2,3,2)$ Bell scenario, whose vertices are well-known.

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arXiv2021

The Entropic Dynamics of Relativistic Quantum Fields in Curved Space-time

It has often been the case in history that the laws of physics have been used as the framework for understanding and implementing information processing. The tacit assumption is that the laws of physics are fundamental and that the notion of information is derived from these laws. Here we take the opposite view: the laws of physics are an application of the rules for processing information. In this dissertation we apply the Entropic Dynamics (ED) framework to construct a quantum dynamics for scalar fields in space-time. We begin by considering a toy model consisting of many interacting particles, resulting in the familiar Schrodinger equation for non-relativistic particles. Using a similar methodology, we construct a theory of quantum scalar fields in flat space-time that is relativistic, but not manifestly so. Here we also discuss a novel way in which the ED of quantum scalar fields appears to evade the so-called Wallstrom objection. To go further towards constructing a manifestly covariant quantum ED of fields on a curved space-time, both fixed and dynamical, we borrow from the "many-time" approaches of P. Weiss, P. Dirac, K. Kuchar, and C. Teitelboim. For a fixed background the result is a manifestly covariant ED of scalar fields that is in the spirit of the covariant quantum theories proposed by S. Tomonaga and J. Schwinger. However, the formalism is sufficiently flexible so as to allow for the possibility of modeling the back reaction of the quantum matter fields on a fully dynamical classical background. The simplest realization of this classical-quantum interaction shares some formal similarity to semi-classical gravity models, and the semi-classical Einstein equations, in particular. We consider such a theory and discuss its plausibility as a candidate for a quantum gravity theory.

gr-qc↗

arXiv2020

The Entropic Dynamics of Quantum Scalar Fields Coupled to Gravity

Entropic dynamics (ED) is a general framework for constructing indeterministic dynamical models based on entropic methods. ED has been used to derive or reconstruct both non-relativistic quantum mechanics and quantum field theory in curved space-time. Here we propose a model for a quantum scalar field propagating in a dynamical space-time. The approach rests on a few key ingredients: (1) Rather than modelling the dynamics of the fields, ED models the dynamics of their probabilities. (2) In accordance with the standard entropic methods of inference the dynamics is dictated by information encoded in constraints. (3) The choice of the physically relevant constraints is dictated by principles of symmetry and invariance. The first such principle imposes the preservation of a symplectic structure which leads to a Hamiltonian formalism with its attendant Poisson brackets and action principle. The second symmetry principle is foliation invariance, which following earlier work by Hojman, Kuchar, and Teitelboim, is implemented as a requirement of path independence. The result is a hybrid ED model that approaches quantum field theory in one limit and classical general relativity in another, but is not fully described by either. A particularly significant prediction of this ED model is that the coupling of quantum fields to gravity implies violations of the quantum superposition principle.

gr-qc↗

arXiv2019

An Entropic Dynamics Approach to Geometrodynamics

In the Entropic Dynamics (ED) framework quantum theory is derived as an application of entropic methods of inference. The physics is introduced through appropriate choices of variables and of constraints that codify the relevant physical information. In previous work, a manifestly covariant ED of quantum scalar fields in a fixed background spacetime was developed. Manifest relativistic covariance was achieved by imposing constraints in the form of Poisson brackets and of intial conditions to be satisfied by a set of local Hamiltonian generators. Our approach succeeded in extending to the quantum domain the classical framework that originated with Dirac and was later developed by Teitelboim and Kuchar. In the present work the ED of quantum fields is extended further by allowing the geometry of spacetime to fully partake in the dynamics. The result is a first-principles ED model that in one limit reproduces quantum mechanics and in another limit reproduces classical general relativity. Our model shares some formal features with the so-called semi-classical approach to gravity.

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arXiv2019

Entropic Dynamics: Reconstructing Quantum Field Theory in Curved Space-time

The Entropic Dynamics reconstruction of quantum mechanics is extended to quantum field theory in curved space-time. The Entropic Dynamics framework, which derives quantum theory as an application of the method of maximum entropy, is combined with the covariant methods of Dirac, Hojman, Kuchař, and Teitelboim, which they used to develop a framework for classical covariant Hamiltonian theories. The goal is to formulate an information-based alternative to current approaches based on algebraic quantum field theory. One key ingredient is the adoption of a local notion of entropic time in which instants are defined on curved three-dimensional surfaces and time evolution consists of the accumulation of changes induced by local deformations of these surfaces. The resulting dynamics is a non-dissipative diffusion that is constrained by the requirements of foliation invariance and incorporates the necessary local quantum potentials. As applications of the formalism we derive the Ehrenfest relations for fields in curved-spacetime and briefly discuss the nature of divergences in quantum field theory.

gr-qc↗

arXiv2018

A Covariant Approach to Entropic Dynamics

Entropic Dynamics (ED) is a framework for constructing dynamical theories of inference using the tools of inductive reasoning. A central feature of the ED framework is the special focus placed on time. In previous work a global entropic time was used to derive a quantum theory of relativistic scalar fields. This theory, however, suffered from a lack of explicit or manifest Lorentz symmetry. In this paper we explore an alternative formulation in which the relativistic aspects of the theory are manifest. The approach we pursue here is inspired by the works of Dirac, Kuchar, and Teitelboim in their development of covariant Hamiltonian methods. The key ingredient here is the adoption of a local notion of time, which we call entropic time. This construction allows the expression of arbitrary notion of simultaneity, in accord with relativity. In order to ensure, however, that this local time dynamics is compatible with the background spacetime we must impose a set of Poisson bracket constraints; these constraints themselves result from requiring the dynamcics to be path independent, in the sense of Teitelboim and Kuchar.

gr-qc↗

arXiv2018

Covariant entropic dynamics: from path independence to Hamiltonians and quantum theory

Entropic Dynamics (ED) is an inference-based framework that seeks to construct dynamical theories of physics without assuming the conventional formalism --- the Hamiltonians, Poisson brackets, Hilbert spaces, etc. --- typically associated with physics. In this work we develop an ED of scalar fields that is both quantum and manifestly covariant. The framework for accomplishing this is inspired by the covariant methods of Dirac, Teitelboim, and Kuchar. In addition to the ostensible result of a covariant quantum ED, we also show how the covariance requirement of path independence proposed by Teitelboim is sufficient for a derivation of Hamiltonian dynamics and also provides a proof of uniqueness for the quantum potential that leads to quantum theory.

quant-ph↗

arXiv2016

Relational Entropic Dynamics of Particles

The general framework of entropic dynamics is used to formulate a relational quantum dynamics. The main new idea is to use tools of information geometry to develop an entropic measure of the mismatch between successive configurations of a system. This leads to an entropic version of the classical best matching technique developed by J. Barbour and collaborators. The procedure is illustrated in the simple case of a system of N particles with global translational symmetry. The generalization to other symmetries whether global (rotational invariance) or local (gauge invariance) is straightforward. The entropic best matching allows a quantum implementation Mach's principles of spatial and temporal relationalism and provides the foundation for a method of handling gauge theories in an informational framework.

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arXiv2014

Entropic Quantization of Scalar Fields

Entropic Dynamics is an information-based framework that seeks to derive the laws of physics as an application of the methods of entropic inference. The dynamics is derived by maximizing an entropy subject to constraints that represent the physically relevant information that the motion is continuous and non-dissipative. Here we focus on the quantum theory of scalar fields. We provide an entropic derivation of Hamiltonian dynamics and using concepts from information geometry derive the standard quantum field theory in the Schroedinger representation.

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