Abstract

Quantum error correcting codes with finite-dimensional Hilbert spaces have yielded new insights on bulk reconstruction in AdS/CFT. In this paper, we give an explicit construction of a quantum error correcting code where the code and physical Hilbert spaces are infinite-dimensional. We define a von Neumann algebra of type II$_1$ acting on the code Hilbert space and show how it is mapped to a von Neumann algebra of type II$_1$ acting on the physical Hilbert space. This toy model demonstrates the equivalence of entanglement wedge reconstruction and the exact equality of bulk and boundary relative entropies in infinite-dimensional Hilbert spaces.

Highlights

  • The study of entanglement entropy has utilized results in the mathematical field of operator algebras [1,2,3]

  • Since AdS/CFT implies that information in the bulk is encoded redundantly in the boundary, quantum error correction is a natural framework in which to elucidate the connection between holographic quantum field theories and their gravity duals [5,6,7,8]

  • In order to study a more realistic toy model where boundary subregions are characterized by infinite-dimensional von Neumann algebras, we should consider quantum error correcting codes defined on infinite-dimensional Hilbert spaces

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Summary

INTRODUCTION

The study of entanglement entropy has utilized results in the mathematical field of operator algebras [1,2,3]. For any jΨi; jΦi ∈ Hcode with jΨi cyclic and separating with respect to Mcode; SΨjΦðMcodeÞ 1⁄4 SuΨjuΦðMphysÞ; and SΨjΦðM0codeÞ 1⁄4 SuΨjuΦðM0physÞ; where SΨjΦðMÞ is the relative entropy: Tensor networks with a finite number of nodes have been used to construct QECC for finite-dimensional Hilbert spaces, which have yielded physical insights into holography [7,9] One such example is the HAPPY code which demonstrates the kinematics of entanglement wedge reconstruction [17]. (iii) Using the code and physical Hilbert spaces and an isometry relating them, we define von Neumann algebras Mcode and Mphys. It follows that our tensor network model satisfies both statements in Theorem 1.1. We first review some preliminary facts about the three qutrit code

The three-qutrit code and a finite tensor network
The code and physical Hilbert spaces
The tensor network of isometries
Definition of Mcode
The commutant of Acode and Mcode
Definition of Mphys and M0phys
DEFINITION OFTHE TENSOR NETWORK MAP
How the tensor network map acts on Acode
How the tensor network map acts on Mcode
How the tensor network map acts on M0code
PROPERTIES OF THE TENSOR NETWORK MAP
Theorems on strong and weak convergence
The tensor network map is linear
The tensor network map commutes with Hermitian conjugation
The tensor network map commutes with multiplication
The tensor network map preserves the norm
The tensor network map satisfies bulk reconstruction
CYCLIC AND SEPARATING VECTORS
Mcode IS A HYPERFINITE TYPE II1 FACTOR
VIII. COMPUTING RELATIVE ENTROPY FOR HYPERFINITE VON NEUMANN ALGEBRAS
Defining relative entropy with respect to a finite-dimensional subalgebra
Monotonicity of relative entropy
CONCLUSION AND OUTLOOK
Hilbert space and bounded operators
Topologies on BðHÞ
Definition of von Neumann algebras
Classification of von Neumann algebras
Norm of the Tomita operator in a finite-dimensional Hilbert space
Example where ScΨjΦ is bounded
Example where ScΨjΦ is unbounded
Preliminary definitions
The example

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