Topological quantum computing with a very noisy network and local error rates approaching one percent

Naomi H. Nickerson; Ying Li; Simon C. Benjamin

doi:10.1038/ncomms2773

Topological Quantum Computing and 3-Manifolds

Quantum Reports ◽

10.3390/quantum3010009 ◽

2021 ◽

Vol 3 (1) ◽

pp. 153-165

Author(s):

Torsten Asselmeyer-Maluga

Keyword(s):

Quantum Computing ◽

Berry Phase ◽

Basic Structure ◽

Quantum States ◽

Point Of View ◽

Surface Topology ◽

Usual Sense ◽

Closed Curves ◽

Topological Quantum ◽

2D System

In this paper, we will present some ideas to use 3D topology for quantum computing. Topological quantum computing in the usual sense works with an encoding of information as knotted quantum states of topological phases of matter, thus being locked into topology to prevent decay. Today, the basic structure is a 2D system to realize anyons with braiding operations. From the topological point of view, we have to deal with surface topology. However, usual materials are 3D objects. Possible topologies for these objects can be more complex than surfaces. From the topological point of view, Thurston’s geometrization theorem gives the main description of 3-dimensional manifolds. Here, complements of knots do play a prominent role and are in principle the main parts to understand 3-manifold topology. For that purpose, we will construct a quantum system on the complements of a knot in the 3-sphere. The whole system depends strongly on the topology of this complement, which is determined by non-contractible, closed curves. Every curve gives a contribution to the quantum states by a phase (Berry phase). Therefore, the quantum states can be manipulated by using the knot group (fundamental group of the knot complement). The universality of these operations was already showed by M. Planat et al.

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Who Needs Category Theory?

10.29007/4dr3 ◽

2020 ◽

Author(s):

Andreas Blass ◽

Yuri Gurevich

Keyword(s):

Quantum Computing ◽

Category Theory ◽

Contentious Issue ◽

Topological Quantum ◽

Mathematical Applications

In mathematical applications, category theory remains a contentious issue, with enthusiastic fans and a skepticalmajority. In a muted form this split applies to the authors ofthis note. When we learned that the only mathematically soundfoundation of topological quantum computing in the literature isbased on category theory, the skeptical author suggested to "decategorize" the foundation. But we discovered, to our surprise, thatcategory theory (or something like it) is necessary for the purpose,for computational reasons. The goal of this note is to give a high-level explanation of that necessity, which avoids details and whichsuggests that the case of topological quantum computing is farfrom unique.

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Quantum computing and the brain: quantum nets, dessins d’enfants and neural networks

EPJ Web of Conferences ◽

10.1051/epjconf/201919800014 ◽

2019 ◽

Vol 198 ◽

pp. 00014

Author(s):

Torsten Asselmeyer-Maluga

Keyword(s):

Neural Networks ◽

Quantum Computing ◽

Feedback Loops ◽

Character Variety ◽

General Transformation ◽

Closed Loops ◽

Dessins D’Enfants ◽

Topological Quantum ◽

The Neural Network ◽

Dessins D'enfants

In this paper, we will discuss a formal link between neural networks and quantum computing. For that purpose we will present a simple model for the description of the neural network by forming sub-graphs of the whole network with the same or a similar state. We will describe the interaction between these areas by closed loops, the feedback loops. The change of the graph is given by the deformations of the loops. This fact can be mathematically formalized by the fundamental group of the graph. Furthermore the neuron has two basic states |0〉 (ground state) and |1〉 (excited state). The whole state of an area of neurons is the linear combination of the two basic state with complex coefficients representing the signals (with 3 Parameters: amplitude, frequency and phase) along the neurons. If something changed in this area, we need a transformation which will preserve this general form of a state (mathematically, this transformation must be an element of the group S L(2; C)). The same argumentation must be true for the feedback loops, i.e. a general transformation of states along the feedback loops is an assignment of this loop to an element of the transformation group. Then it can be shown that the set of all signals forms a manifold (character variety) and all properties of the network must be encoded in this manifold. In the paper, we will discuss how to interpret learning and intuition in this model. Using the Morgan-Shalen compactification, the limit for signals with large amplitude can be analyzed by using quasi-Fuchsian groups as represented by dessins d’enfants (graphs to analyze Riemannian surfaces). As shown by Planat and collaborators, these dessins d’enfants are a direct bridge to (topological) quantum computing with permutation groups. The normalization of the signal reduces to the group S U(2) and the whole model to a quantum network. Then we have a direct connection to quantum circuits. This network can be transformed into operations on tensor networks. Formally we will obtain a link between machine learning and Quantum computing.

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THE QUANTUM WORLD AND QUANTUM COMPUTING: FUNDAMENTAL ISSUES

Journal of Knot Theory and Its Ramifications ◽

10.1142/s0218216511008711 ◽

2011 ◽

Vol 20 (01) ◽

pp. 179-202

Author(s):

WILLIAM C. PARKE ◽

ALI ESKANDARIAN

Keyword(s):

Quantum Computing ◽

Quantum Theory ◽

Quantum Information ◽

Information Transfer ◽

Space Time ◽

Topological Quantum ◽

Non Locality

Some of the fundamental issues in quantum theory related to quantum computing are reviewed and discussed. Particularly emphasized is the need to be diligent in what quantum theory predicts, and what it does not. The non-intuitive features of quantum theory, that are often associated with aspects of non-locality and that also arise in quantum computing and quantum information transfer, are described. Some discussion of topological quantum computing using space-time strings is presented, as well as general notions about quantum computing.

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Braiding and Majorana fermions

Journal of Knot Theory and Its Ramifications ◽

10.1142/s0218216517430015 ◽

2017 ◽

Vol 26 (09) ◽

pp. 1743001 ◽

Cited By ~ 2

Author(s):

Louis H. Kauffman

Keyword(s):

Quantum Computing ◽

Clifford Algebra ◽

General Result ◽

Braid Group ◽

Clifford Algebras ◽

Majorana Fermions ◽

Group Representations ◽

Topological Quantum

In this paper, we study unitary braid group representations associated with Majorana fermions. Majorana fermions are represented by Majorana operators, elements of a Clifford algebra. The paper proves a general result about braid group representations associated with Clifford algebras and compares this result with the Ivanov braiding associated with Majorana operators and with other braiding representations associated with Majorana fermions such as the Fibonacci model for universal topological quantum computing.

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