Research

# This Year-ish in Theoretical Physics

The previous episode of “this week-ish” was posted on June 5. Its been six months since then. I guess its time to post another volume but to be fair the title of this post has been changed to reflect the longer time span its contents refer to.

# Gravity as Quantum Computation (contd from Vol. 1)

In the previous episode of “this week-ish” I wrote about the emerging relationship between quantum computation and quantum gravity, especially with regards to a recent paper by Caputa and Magan [1]. A recent paper [2] has approached this problem from a slightly different perspective.

In [1] and related works the method pioneered by Nielsen is used to argue that gravity sets the rules for optimal quantum computation. I will elaborate on the idea behind these approaches in another post. Taken together all these works add greater weight to what I like to call the computational universe hypothesis – the premise that all physical phenomena can be viewed as computational processes and that moreover the particle content of our Universe is precisely such that it provides the minimum number of elementary gates needed for universal quantum computation. More on this in a later post.

# Quantum Channels as Thermal Engines

Bringing quantum information still closer to statistical mechanics and thermodynamics comes this exciting paper [3] which suggests that one should view quantum channels – essentially operators which map one quantum system into another – as thermodynamic objects with which one can associate a unique quantity called the thermodynamic capacity. The physical interpretation of this quantity is, I quote: “the work required to simulate many repetitions of a quantum process employing many repetitions of another quantum process becomes equal to the difference of the respective thermodynamic capacities.”

# Experimental Evidence for Lorentz Violation

This [4] is probably one of the most exciting experimental results in recent memory. Lorentz invariance is one of the sacred cornerstones of modern theoretical physics and theories such as loop quantum gravity have often been shrugged off because of the (misguided) belief that discrete quantum geometry is not compatible with microscopic Lorentz invariance. Such beliefs were only strengthened by the negative results of searches for Lorentz violation using the Fermi space telescope [5]. It is therefore very gratifying to see published works which point out that (possible) Lorentz violation has already been see by the neutrino observatory known as IceCube. Unverified reports suggest that on finding traces of Lorentz violation the IceCube scientists were heard to yell out “it was a good day!”

# Loops ’19: Fun with Kac-Moody algebras and quantum error correction

And, finally, we come to what was without a doubt the most exciting event of 2019. Loops’ 19 – the biannual meeting where loop quantum gravity people from all over the globe gather together to plot the overthrow of string theory (muahahahaha) – was held at Penn State. Surprisingly enough my abstract was selected for a parallel talk. Even more surprising was the fact that I managed to make it there at all given the bureaucratic maze called “life” here in India, which I had to navigate through!

It was my first time attending Loops, which made especially wonderful by the fact that Penn State is where I did my PhD. And, no, it was NOT with Abhay as my advisor if you must ask!

My talk was on recent work I have done relating quantum error correction to diffeomorphism invariance of spin networks. Essentially my claim is that LQG naturally incorporates quantum error correcting codes in the form of “noiseless subsystems” [6, 7, 8] which, conveniently enough can also be viewed as elementary particles [9, 10, 11, 12, 13, 14, 15, 16]. As chance would have it Laurent Freidel presented his most recent work (with Daniele Pranzetti and Etera Livine) [17] in an earlier parallel talk. I did have the chance to point out that their idea of replacing spin network edges with tubes was not exactly new and that several other researchers, including me, had suggested the same picture long before their own work. Apparently they were not in the mood to humour my claims of precendence. The response is understandable. As a leading LQG researcher recently pointedly mentioned: “[my] papers are unpublished and almost uncited” and moreover, referring to one of my papers,”[it] is rather messy, mixing well-known physics (Hall effect) with original ideas and known ideas (and even almost wrong ideas), all on equal footing.” Given this prior feedback I was not surprised by the lack of a response.

But, I digress.

What matters is that, after much procrastinating, I have finally put my ideas down in another – hopefully not so “messy” – paper [18]. I cannot be held guilty of being either a great fan of, or even being very capable of, mathematical rigor. Thus, those looking for page upon page of math will be disappointed. The physical picture is, however, I believe very clear. I would love to hear more from anybody who does find the time to look through my work.

That’s all folks. Wishing you all a very happy new year. I leave you with some wonderful memories from Loops’ 19.

[1] P. Caputa and J. M. Magan, “Quantum Computation as Gravity,” , 2018.
[Bibtex]
@article{Caputa2018Quantum,
Abstract = {We formulate Nielsen's geometric approach to complexity in the context of two dimensional conformal field theories, where series of conformal transformations are interpreted as unitary circuits. We show that the complexity functional can be written as the Polyakov action of two dimensional gravity or, equivalently, as the geometric action on the coadjoint orbits of the Virasoro group. This way, we argue that gravity sets the rules for optimal quantum computation in conformal field theories.},
Archiveprefix = {arXiv},
Arxivid = {1807.04422},
Author = {Caputa, Pawel and Magan, Javier M.},
Date-Modified = {2019-05-22 10:16:46 +0530},
Eprint = {1807.04422},
File = {:Users/deepak/ownCloud/root/research/mendeley/Caputa, Magan{\_}Quantum Computation as Gravity{\_}2018.pdf:pdf},
Mendeley-Groups = {Computational Universe},
Month = {jul},
Title = {{Quantum Computation as Gravity}},
Url = {http://arxiv.org/abs/1807.04422},
Year = {2018},
Bdsk-Url-1 = {http://arxiv.org/abs/1807.04422}}
[2] H. A. Camargo, M. P. Heller, R. Jefferson, and J. Knaute, “Path Integral Optimization as Circuit Complexity,” Physical review letters, vol. 123, iss. 1, p. 11601, 2019.
[Bibtex]
@article{Camargo2019Path,
Abstract = {Early efforts to understand complexity in field theory have primarily employed a geometric approach based on the concept of circuit complexity in quantum information theory. In a parallel vein, it has been proposed that certain deformations of the Euclidean path integral that prepares a given operator or state may provide an alternative definition, whose connection to the standard notion of complexity is less apparent. In this letter, we bridge the gap between these two proposals in two-dimensional conformal field theories, by explicitly showing how the latter approach from path integral optimization may be given a concrete realization within the standard gate counting framework. In particular, we show that when the background geometry is deformed by a Weyl rescaling, a judicious gate counting allows one to recover the Liouville action as a particular choice within a more general class of cost functions.},
Archiveprefix = {arXiv},
Arxivid = {1904.02713},
Author = {Camargo, Hugo A. and Heller, Michal P. and Jefferson, Ro and Knaute, Johannes},
Date-Modified = {2019-08-04 21:27:21 +0530},
Doi = {10.1103/PhysRevLett.123.011601},
Eprint = {1904.02713},
File = {:Users/deepak/ownCloud/root/research/mendeley/Camargo et al.{\_}Path Integral Optimization as Circuit Complexity{\_}2019.pdf:pdf},
Issn = {0031-9007},
Journal = {Physical Review Letters},
Mendeley-Groups = {Complexity,Quantum Computation,Computational Universe},
Month = {jul},
Number = {1},
Pages = {011601},
Title = {{Path Integral Optimization as Circuit Complexity}},
Url = {http://arxiv.org/abs/1904.02713},
Volume = {123},
Year = {2019},
Bdsk-Url-1 = {https://doi.org/10.1103/PhysRevLett.123.011601},
Bdsk-Url-2 = {http://arxiv.org/abs/1904.02713}}
[3] P. Faist, M. Berta, and F. Brandão, “Thermodynamic Capacity of Quantum Processes,” Physical review letters, vol. 122, iss. 20, p. 200601, 2019.
[Bibtex]
@article{Faist2019Thermodynamic,
Abstract = {Thermodynamics imposes restrictions on what state transformations are possible. In the macroscopic limit of asymptotically many independent copies of a state---as for instance in the case of an ideal gas---the possible transformations become reversible and are fully characterized by the free energy. In this letter, we present a thermodynamic resource theory for quantum processes that also becomes reversible in the macroscopic limit. Namely, we identify a unique single-letter and additive quantity, the thermodynamic capacity, that characterizes the "thermodynamic value" of a quantum channel. As a consequence the work required to simulate many repetitions of a quantum process employing many repetitions of another quantum process becomes equal to the difference of the respective thermodynamic capacities. For our proof, we construct explicit universal implementations of quantum processes using Gibbs-preserving maps and a battery, requiring an amount of work asymptotically equal to the thermodynamic capacity. This implementation is also possible with thermal operations in the case of time-covariant quantum processes or when restricting to independent and identical inputs. In our derivations we make extensive use of Schur-Weyl duality and other information-theoretic tools, leading to a generalized notion of quantum typical subspaces.},
Archiveprefix = {arXiv},
Arxivid = {1807.05610},
Author = {Faist, Philippe and Berta, Mario and Brand{\~{a}}o, Fernando},
Date-Modified = {2019-06-12 10:33:08 +0530},
Doi = {10.1103/PhysRevLett.122.200601},
Eprint = {1807.05610},
File = {:Users/deepak/ownCloud/root/research/mendeley/Faist, Berta, Brand{\~{a}}o{\_}Thermodynamic Capacity of Quantum Processes{\_}2018.pdf:pdf},
Issn = {0031-9007},
Journal = {Physical Review Letters},
Mendeley-Groups = {Quantum Computation,Quantum Thermodynamics},
Month = {may},
Number = {20},
Pages = {200601},
Title = {{Thermodynamic Capacity of Quantum Processes}},
Url = {http://arxiv.org/abs/1807.05610 http://dx.doi.org/10.1103/PhysRevLett.122.200601 https://arxiv.org/abs/1807.05610 https://link.aps.org/doi/10.1103/PhysRevLett.122.200601},
Volume = {122},
Year = {2019},
Bdsk-Url-2 = {https://doi.org/10.1103/PhysRevLett.122.200601}}
[4] Y. Huang, H. Li, and B. Ma, “Consistent Lorentz violation features from near-TeV IceCube neutrinos,” , 2019.
[Bibtex]
@article{Huang2019Consistent,
Abstract = {A recent proposal to associate 60{\~{}}TeV to 2{\~{}}PeV IceCube neutrino events with gamma-ray bursts{\~{}}(GRBs) indicates the Lorentz violation of cosmic neutrinos and leads further to the {\$}CPT{\$} symmetry violation between neutrinos and antineutrinos. Here we find that another 12 northern hemisphere track events possibly correlated with GRBs from three-year IceCube data satisfy the same regularity at a lower energy scale around 1{\~{}}TeV. The combined fitting indicates a Lorentz violation scale {\$}{\{}E{\}}{\_}{\{}\backslashrm LV{\}}=(6.4\backslashpm 1.5)\backslashtimes10{\^{}}{\{}17{\}}{\~{}}{\{} \backslashrm GeV{\}}{\$} and an intrinsic time difference {\$}{\{}\backslashDelta {\{}t{\}}{\_}{\{}\backslashrm in{\}}=(-2.8\backslashpm 0.7)\backslashtimes10{\^{}}2{\~{}}{\{}\backslashrm s{\}}{\}}{\$}, from which we find an earlier emission of neutrinos than photons at the GRB source. We also suggest analyzing neutrino events detected a few minutes before the GRB trigger time to test the {\$}CPT{\$} violation of ultrahigh-energy neutrinos.},
Archiveprefix = {arXiv},
Arxivid = {1906.07329},
Author = {Huang, Yanqi and Li, Hao and Ma, Bo-Qiang},
Date-Modified = {2019-08-05 10:15:31 +0530},
Eprint = {1906.07329},
File = {:Users/deepak/ownCloud/root/research/mendeley/Huang, Li, Ma{\_}Consistent Lorentz violation features from near-TeV IceCube neutrinos{\_}2019.pdf:pdf},
Mendeley-Groups = {Loop Quantum Gravity},
Title = {{Consistent Lorentz violation features from near-TeV IceCube neutrinos}},
Url = {https://arxiv.org/abs/1906.07329},
Year = {2019},
Bdsk-Url-1 = {https://arxiv.org/abs/1906.07329}}
[5] R. J. Nemiroff, R. Connolly, J. Holmes, and A. B. Kostinski, Bounds on spectral dispersion from fermi-detected gamma ray bursts, 2012.
[Bibtex]
@misc{Nemiroff2012Bounds,
Abstract = {Data from four Fermi-detected gamma-ray bursts (GRBs) is
used to set limits on spectral dispersion of
electromagnetic radiation across the universe. The analysis
focuses on photons recorded above 1 GeV for Fermi detected
GRB 080916C, GRB 090510A, GRB 090902B, and GRB 090926A
because these high-energy photons yield the tightest bounds
on light dispersion. It is shown that significant photon
bunches in GRB 090510A, possibly classic GRB pulses, are
remarkably brief, an order of magnitude shorter in duration
than any previously claimed temporal feature in this energy
range. Although conceivably a \$\>3 \sigma\$
fluctuation, when taken at face value, these pulses lead to
an order of magnitude tightening of prior limits on photon
dispersion. Bound of \$\Delta c / c \< 6.94\$ x
\$10^{-21}\$ is thus obtained. Given generic dispersion
relations where the time delay is proportional to the
photon energy to the first or second power, the most
stringent limits on the dispersion strengths were \$k\_1 \<\$ 1.61 x \$10^{-5}\$ sec Gpc\$^{-1}\$ GeV\$^{-1}\$
and \$k\_2 \<\$ 3.57 x \$10^{-7}\$ sec Gpc\$^{-1}\$
GeV\$^{-2}\$ respectively. Such limits constrain dispersive
effects created, for example, by the spacetime foam of
quantum gravity. In the context of quantum gravity, our
bounds set \$M\_1 c^2\$ greater than 525 times the Planck
mass, suggesting that spacetime is smooth at energies near
and slightly above the Planck mass.},
Archiveprefix = {arXiv},
Author = {Nemiroff, Robert J. and Connolly, Ryan and Holmes, Justin and Kostinski, Alexander B.},
Citeulike-Article-Id = {9819611},
Date-Modified = {2013-01-14 00:14:48 +0530},
Day = {18},
Eprint = {1109.5191},
Keywords = {dispersion, experiment, fermi\_telescope, gamma\_ray\_bursts, lorentz\_violation, observational, quantum\_geometry, quantum\_gravity},
Month = apr,
Posted-At = {2013-01-13 18:44:08},
Priority = {2},
Title = {Bounds on Spectral Dispersion from Fermi-detected Gamma Ray Bursts},
Url = {http://arxiv.org/abs/1109.5191},
Year = {2012},
Bdsk-Url-1 = {http://arxiv.org/abs/1109.5191}}
[6] P. Zanardi and M. Rasetti, “Noiseless quantum codes,” Physical review letters, vol. 79, iss. 17, p. 3306–3309, 1997.
[Bibtex]
@article{Zanardi1997Noiseless,
Abstract = {In this paper we study a model quantum register R made of
N replicas (cells) of a given finite-dimensional quantum
system S. Assuming that all cells are coupled with a common
environment with equal strength we show that; for N large
enough; in the Hilbert space of R there exists a linear
subspace C N which is dynamically decoupled from the
environment. The states in C N evolve unitarily and are
therefore decoherence-dissipation free. The space C N
realizes a noiseless quantum code in which information can
be stored; in principle; for an arbitrarily long time
without being affected by errors.},
Author = {Zanardi, P. and Rasetti, M.},
Citeulike-Article-Id = {6444201},
Day = {27},
Doi = {10.1103/PhysRevLett.79.3306},
Journal = {Physical Review Letters},
Keywords = {decoherence, file-import-09-12-27, quantum-computation, quantum\_code},
Month = {Oct},
Number = {17},
Pages = {3306--3309},
Posted-At = {2009-12-27 12:17:42},
Priority = {2},
Publisher = {American Physical Society},
Title = {Noiseless Quantum Codes},
Url = {http://dx.doi.org/10.1103/PhysRevLett.79.3306},
Volume = {79},
Year = {1997},
Bdsk-Url-1 = {http://dx.doi.org/10.1103/PhysRevLett.79.3306}}
[7] D. W. Kribs and F. Markopoulou, “Geometry from quantum particles,” , 2005.
[Bibtex]
@article{Kribs2005Geometry,
Abstract = {We investigate the possibility that a background
independent quantum theory of gravity is not a theory of
quantum geometry. We provide a way for global spacetime
symmetries to emerge from a background independent theory
without geometry. In this, we use a quantum information
theoretic formulation of quantum gravity and the method of
noiseless subsystems in quantum error correction. This is
also a method that can extract particles from a quantum
geometric theory such as a spin foam model.},
Archiveprefix = {arXiv},
Author = {Kribs, David W. and Markopoulou, Fotini},
Citeulike-Article-Id = {687721},
Date-Modified = {2012-06-04 11:43:24 +0530},
Day = {11},
Eprint = {gr-qc/0510052},
Keywords = {computational\_universe, error\_correction, fotini, noiseless\_subsystems, quantum\_computation, quantum\_geometry, quantum\_gravity, spin-foams},
Month = oct,
Posted-At = {2012-06-04 07:13:13},
Priority = {2},
Title = {Geometry from quantum particles},
Url = {http://arxiv.org/abs/gr-qc/0510052},
Year = {2005},
Bdsk-Url-1 = {http://arxiv.org/abs/gr-qc/0510052}}
[8] D. Kribs, R. Laflamme, and D. Poulin, “Unified and generalized approach to quantum error correction,” Physical review letters, vol. 94, iss. 18, 2005.
[Bibtex]
@article{Kribs2005Unified,
Abstract = {We present a unified approach to quantum error correction, called operator quantum error correction. This scheme relies on a generalized notion of noiseless subsystems that is not restricted to the commutant of the interaction algebra. We arrive at the unified approach, which incorporates the known techniques -- i.e. the standard error correction model, the method of decoherence-free subspaces, and the noiseless subsystem method -- as special cases, by combining active error correction with this generalized noiseless subsystem method. Moreover, we demonstrate that the quantum error correction condition from the standard model is a necessary condition for all known methods of quantum error correction.},
Archiveprefix = {arXiv},
Arxivid = {quant-ph/0412076},
Author = {Kribs, David and Laflamme, Raymond and Poulin, David},
Date-Modified = {2019-06-12 19:31:54 +0530},
Doi = {10.1103/PhysRevLett.94.180501},
Eprint = {0412076},
File = {:Users/deepak/ownCloud/root/research/mendeley/Kribs, Laflamme, Poulin{\_}Unified and generalized approach to quantum error correction{\_}2005.pdf:pdf},
Issn = {00319007},
Journal = {Physical Review Letters},
Mendeley-Groups = {Quantum Error Correction},
Month = {dec},
Number = {18},
Primaryclass = {quant-ph},
Title = {{Unified and generalized approach to quantum error correction}},
Url = {http://arxiv.org/abs/quant-ph/0412076},
Volume = {94},
Year = {2005},
Bdsk-Url-1 = {https://doi.org/10.1103/PhysRevLett.94.180501},
Bdsk-Url-2 = {http://arxiv.org/abs/quant-ph/0412076}}
[9] S. O. Bilson-Thompson, “A topological model of composite preons,” Arxiv preprint hep-ph/0503213, iss. December 2005, p. 6, 2005.
[Bibtex]
@article{Bilson-Thompson2005A-topological,
Abstract = {We describe a simple model, based on the preon model of Shupe and Harari, in which the binding of preons is represented topologically. We then demonstrate a direct correspondence between this model and much of the known phenomenology of the Standard Model. In particular we identify the substructure of quarks, leptons and gauge bosons with elements of the braid group {\$}B{\_}3{\$}. Importantly, the preonic objects of this model require fewer assumed properties than in the Shupe/Harari model, yet more emergent quantities, such as helicity, hypercharge, and so on, are found. Simple topological processes are identified with electroweak interactions and conservation laws. The objects which play the role of preons in this model may occur as topological structures in a more comprehensive theory, and may themselves be viewed as composite, being formed of truly fundamental sub-components, representing exactly two levels of substructure within quarks and leptons.},
Archiveprefix = {arXiv},
Arxivid = {hep-ph/0503213},
Author = {Bilson-Thompson, Sundance O.},
Date-Modified = {2019-06-18 18:16:12 -0400},
Doi = {hlthaff.25.w447 [pii]\r10.1377/hlthaff.25.w447},
Eprint = {0503213},
File = {:Users/deepak/ownCloud/root/research/mendeley/Bilson-Thompson{\_}A topological model of composite preons{\_}2005(2).pdf:pdf;:Users/deepak/ownCloud/root/research/mendeley/Bilson-Thompson{\_}A topological model of composite preons{\_}2005.pdf:pdf},
Isbn = {1544-5208 (Electronic)$\backslash$r1544-5208 (Linking)},
Journal = {arXiv preprint hep-ph/0503213},
Keywords = {10,12,60,braids,composite models,dm,model,pacs,preons,rc,standard,topology},
Mendeley-Groups = {Braids and GFT},
Mendeley-Tags = {braids,model,preons,standard},
Month = {mar},
Number = {December 2005},
Pages = {6},
Pmid = {16973648},
Primaryclass = {hep-ph},
Title = {{A topological model of composite preons}},
Type = {Electronic citation},
Url = {http://arxiv.org/abs/hep-ph/0503213},
Year = {2005},
Bdsk-Url-1 = {http://arxiv.org/abs/hep-ph/0503213},
Bdsk-Url-2 = {https://doi.org/10.1377/hlthaff.25.w447}}
[10] S. O. Bilson-Thompson, F. Markopoulou, and L. Smolin, Quantum gravity and the standard model, 2006.
[Bibtex]
@misc{Bilson-Thompson2006Quantum,
Abstract = {We show that a class of background independent models of
quantum spacetime have local excitations that can be mapped
to the first generation fermions of the standard model of
particle physics. These states propagate coherently as they
can be shown to be noiseless subsystems of the microscopic
quantum dynamics. These are identified in terms of certain
patterns of braiding of graphs, thus giving a quantum
gravitational foundation for the topological preon model
proposed by one of us. These results apply to a large
class of theories in which the Hilbert space has a basis of
states given by ribbon graphs embedded in a
three-dimensional manifold up to diffeomorphisms, and the
dynamics is given by local moves on the graphs, such as
arise in the representation theory of quantum groups. For
such models, matter appears to be already included in the
microscopic kinematics and dynamics.},
Author = {Bilson-Thompson, Sundance O. and Markopoulou, Fotini and Smolin, Lee},
Citeulike-Article-Id = {6444359},
Date-Modified = {2012-08-19 20:22:22 +0530},
Eprint = {hep-th/0603022},
Keywords = {braids, file-import-09-12-27, gravity, model, preons, quantum, standard, topology},
Month = {Mar},
Posted-At = {2009-12-27 12:17:44},
Priority = {2},
Title = {Quantum gravity and the standard model},
Url = {http://arxiv.org/abs/hep-th/0603022},
Year = {2006},
Bdsk-Url-1 = {http://arxiv.org/abs/hep-th/0603022}}
[11] J. Hackett, Invariants of braided ribbon networks, 2011.
[Bibtex]
@misc{Hackett2011aInvariants,
Abstract = {We present a consistent definition for braided ribbon
networks in 3-dimensional manifolds, unifying both three
and four valent networks in a single framework. We present
evolution moves for these networks which are dual to the
Pachner moves on simplices and present an invariant of this
evolution. Finally we relate these results back to previous
work in the subject.},
Archiveprefix = {arXiv},
Author = {Hackett, Jonathan},
Citeulike-Article-Id = {12028332},
Date-Modified = {2013-02-15 04:28:12 +0530},
Day = {25},
Eprint = {1106.5096},
Keywords = {bilson-thompson, braids, jonathan\_hackett, pachner\_moves, quantum\_gravity, simplicial\_geometry, topological\_invariant},
Month = jun,
Posted-At = {2013-02-14 22:56:58},
Priority = {2},
Title = {Invariants of Braided Ribbon Networks},
Url = {http://arxiv.org/abs/1106.5096},
Year = {2011},
Bdsk-Url-1 = {http://arxiv.org/abs/1106.5096}}
[12] J. Hackett, “Invariants of spin networks from braided ribbon networks,” , 2011.
[Bibtex]
@article{Hackett2011bInvariants,
Abstract = {We connect Braided Ribbon Networks to the states of loop
quantum gravity. Using this connection we present the
reduced link as an invariant which captures information
from the embedding of the spin-networks. We also present a
means of understanding higher valent nodes in the context
of braided ribbon networks and an interpretation of the
dual of these nodes as polygons or polyhedra.},
Archiveprefix = {arXiv},
Author = {Hackett, Jonathan},
Citeulike-Article-Id = {10732817},
Date-Modified = {2013-02-15 04:28:19 +0530},
Day = {25},
Eprint = {1106.5095},
Keywords = {bilson-thompson, braids, geometry, jonathan\_hackett, linking, lqg, quantum\_gravity, standard\_model, topological\_invariant},
Month = jun,
Posted-At = {2012-06-04 07:07:42},
Priority = {2},
Title = {Invariants of Spin Networks from Braided Ribbon Networks},
Url = {http://arxiv.org/abs/1106.5095},
Year = {2011},
Bdsk-Url-1 = {http://arxiv.org/abs/1106.5095}}
[13] Y. Wan, “On braid excitations in quantum gravity,” , 2007.
[Bibtex]
@article{Wan2007Braid,
Abstract = {We propose a new notation for the states in some models of
quantum gravity, namely 4-valent spin networks embedded in
a topological three manifold. With the help of this
notation, equivalence moves, namely translations and
rotations, can be defined, which relate the projections of
diffeomorphic embeddings of a spin network. Certain types
of topological structures, viz 3-strand braids as local
excitations of embedded spin networks, are defined and
classified by means of the equivalence moves. This paper
formulates a mathematical approach to the further research
of particle-like excitations in quantum gravity.},
Author = {Wan, Yidun},
Citeulike-Article-Id = {6444354},
Eprint = {0710.1312},
Keywords = {braids, elementary, file-import-09-12-27, gravity, model, particles, quantum, standard},
Month = {Oct},
Posted-At = {2009-12-27 12:17:44},
Priority = {4},
Title = {On Braid Excitations in Quantum Gravity},
Url = {http://arxiv.org/abs/0710.1312},
Year = {2007},
Bdsk-Url-1 = {http://arxiv.org/abs/0710.1312}}
[14] Y. Wan, “Effective theory of braid excitations of quantum geometry in terms of feynman diagrams,” , 2009.
[Bibtex]
@article{Wan2009Effective,
Abstract = {We study interactions amongst topologically conserved
excitations of quantum theories of gravity, in particular
the braid excitations of four-valent spin networks. These
have been shown previously to propagate and interact under
evolution rules of spin foam models. We show that the
dynamics of these braid excitations can be described by an
effective theory based on Feynman diagrams. In this
language, braids which are actively interacting are
analogous to bosons, in that the topological conservation
laws permit them to be singly created and destroyed.
Exchanges of these excitations give rise to interactions
between braids which are charged under the topological
conservation rules.},
Archiveprefix = {arXiv},
Author = {Wan, Yidun},
Citeulike-Article-Id = {3866445},
Date-Modified = {2011-05-29 17:12:06 +0530},
Day = {8},
Eprint = {0809.4464},
Keywords = {braids, effective-theory, elementary\_particles, feynman\_graphs, quantum\_geometry, topology, yidun\_wan},
Month = jan,
Posted-At = {2011-05-29 12:41:53},
Priority = {2},
Title = {Effective Theory of Braid Excitations of Quantum Geometry in terms of Feynman Diagrams},
Url = {http://arxiv.org/abs/0809.4464},
Year = {2009},
Bdsk-Url-1 = {http://arxiv.org/abs/0809.4464}}
[15] D. Vaid, “Embedding the bilson-thompson model in an lqg-like framework,” , 2010.
[Bibtex]
@article{Vaid2010Embedding,
Abstract = {We argue that the Quadratic Spinor Lagrangian approach
allows us to approach the problem of forming a geometrical
condensate of spinorial tetrads in a natural manner. This,
along with considerations involving the discrete symmetries
of lattice triangulations, lead us to discover that the
quasiparticles of such a condensate are tetrahedra with
braids attached to its faces and that these braid
attachments correspond to the preons in Bilson-Thompson's
model of elementary particles. These "spatoms" can then be
put together in a tiling to form more complex structures
which encode both geometry and matter in a natural manner.
We conclude with some speculations on the relation between
this picture and the computational universe hypothesis.},
Archiveprefix = {arXiv},
Author = {Vaid, Deepak},
Citeulike-Article-Id = {7265311},
Date-Modified = {2010-06-08 04:38:45 +0530},
Day = {8},
Eprint = {1002.1462},
Keywords = {bilson-thompson, braids, computational\_universe, condensate, defects, elementary\_particles, quadratic-spinor-lagrangian, quantum\_gravity, standard\_model, topology},
Month = {Feb},
Posted-At = {2010-06-08 00:08:18},
Priority = {2},
Title = {Embedding the Bilson-Thompson model in an LQG-like framework},
Url = {http://arxiv.org/abs/1002.1462},
Year = {2010},
Bdsk-Url-1 = {http://arxiv.org/abs/1002.1462}}
[16] D. Vaid, Elementary particles as gates for universal quantum computation, 2013.
[Bibtex]
@misc{Vaid2013Elementary,
Abstract = {It is shown that there exists a mapping between the
fermions of the Standard Model ({SM}) represented as braids
in the {Bilson-Thompson} model, and a set of gates which
can perform Universal Quantum Computation ({UQC}). This
leads us to conjecture that the "Computational Universe
Hypothesis" ({CUH}) can be given a concrete implementation
in a new physical framework where elementary particles and
the gauge bosons (which intermediate interactions between
fermions) are interpreted as the components of a quantum
computational network, with the particles serving as
quantum computational gates and the gauge fields as the
information carrying entities.},
Archiveprefix = {arXiv},
Author = {Vaid, Deepak},
Citeulike-Article-Id = {12456844},
Date-Modified = {2013-07-02 10:14:01 +0530},
Day = {29},
Eprint = {1307.0096},
Keywords = {bilson-thompson, braids, computational\_universe, fqxi, large\_gauge\_transformation, lqg, preons, quantum\_computation, quantum\_gates, quantum\_gravity, universal, vaid\_d},
Month = jun,
Posted-At = {2013-07-02 05:42:42},
Priority = {2},
Title = {Elementary Particles as Gates for Universal Quantum Computation},
Url = {http://arxiv.org/abs/1307.0096},
Year = {2013},
Bdsk-Url-1 = {http://arxiv.org/abs/1307.0096}}
[17] L. Freidel, E. R. Livine, and D. Pranzetti, “Gravitational edge modes: From Kac-Moody charges to Poincar$\backslash$’e networks,” , 2019.
[Bibtex]
@article{Freidel2019Gravitational,
Abstract = {We revisit the canonical framework for general relativity in its connection-vierbein formulation, recasting the Gauss law, the Bianchi identity and the space diffeomorphism bulk constraints as conservation laws for boundary surface charges, respectively electric, magnetic and momentum charges. Partitioning the space manifold into 3D regions glued together through their interfaces, we focus on a single domain and its punctured 2D boundary. The punctures carry a ladder of Kac-Moody edge modes, whose 0-modes represent the electric and momentum charges while the higher modes describe the stringy vibration modes of the 1D-boundary around each puncture. In particular, this allows to identify missing observables in the discretization scheme used in loop quantum gravity and leads to an enhanced theory upgrading spin networks to tube networks carrying Virasoro representations. In the limit where the tubes are contracted to 1D links and the string modes neglected, we do not just recover loop quantum gravity but obtain a more general structure: Poincar$\backslash$'e charge networks, which carry a representation of the 3D diffeomorphism boundary charges on top of the {\$}\backslashmathrm{\{}SU{\}}(2){\$} fluxes and gauge transformations.},
Archiveprefix = {arXiv},
Arxivid = {1906.07876},
Author = {Freidel, Laurent and Livine, Etera R. and Pranzetti, Daniele},
Date-Modified = {2019-06-20 11:16:36 -0400},
Eprint = {1906.07876},
File = {:Users/deepak/ownCloud/root/research/mendeley/Freidel, Livine, Pranzetti{\_}Gravitational edge modes From Kac-Moody charges to Poincar'e networks{\_}2019.pdf:pdf},
Mendeley-Groups = {Preons and Standard Model},
Month = {jun},
Title = {{Gravitational edge modes: From Kac-Moody charges to Poincar$\backslash$'e networks}},
Url = {http://arxiv.org/abs/1906.07876},
Year = {2019},
Bdsk-Url-1 = {http://arxiv.org/abs/1906.07876}}
[18] D. Vaid, “Quantum Error Correction in Loop Quantum Gravity,” , 2019.
[Bibtex]
@article{Vaid2019Quantum,
Abstract = {Previous works (by Almiehri, Dong, Harlow, Pastakawski, Preskill, Yoshida and others) have established that quantum error correction plays an important role in understanding how the bulk degrees of freedom of an Anti-deSitter spacetime are encoded in the degrees of freedom of the boundary Conformal Field Theory. In previous work $\backslash$cite{\{}Vaid2013Elementary{\}} I have argued that the Bilson-Thompson model $\backslash$cite{\{}Bilson-Thompson2006Quantum,Vaid2010Embedding{\}} of elementary particles allows us to view elementary particles as gates for universal quantum computation. In the present work I show that the Bilson-Thompson model, where elementary particles are represented by elements of the framed braid group on three strands, provides an explicit model for the generation of qutrit (three-qubit) states which are the ingredients of Shor's quantum error correcting code. This allows, for the first time, to connect in a concrete manner the proposals of Almheiri, Pastawski, Preskill and others regarding the role of quantum error correction in quantum gravity, to a viable model of elementary particles. Loop Quantum Gravity (LQG), the theory of quantum gravity in which such topological excitations exist, can thus serve as the glue which can connect AdS/CFT based approaches to quantum gravity to the well understood physics of the Standard Model.},
Archiveprefix = {arXiv},
Arxivid = {1912.11725},
Author = {Vaid, Deepak},
Bdsk-Url-1 = {https://arxiv.org/abs/1912.11725}}