Tensor Networks: from Simulations to Holography III

COVID-19 information for PI Residents and Visitors

Conference Date: 
Monday, November 16, 2020 (All day) to Friday, November 20, 2020 (All day)
Scientific Areas: 
Quantum Fields and Strings


Important Information Regarding COVID-19 Coronavirus 
Perimeter Institute is committed to providing a safe environment to all staff and visitors.  As the COVID-19 coronavirus continues to evolve, precautionary steps are being put in place to minimize the risk associated with this outbreak. As such, the “Tensor Networks: From Simulations to Holography III” conference has now become a virtual event. 


This workshop aims to stimulate the exchange between different research areas where tensor network techniques are applied, in particular lattice gauge theories, holography and condensed matter physics.
 
For further information and to register for the conference, please click here
 
  • Mari-Carmen Banuls, Max Planck Institute of Quantum Optics
  • Krzysztof Cichy, Adam Mickiewicz University
  • Ignacio Cirac, Max Planck Institute of Quantum Optics
  • Bartek Czech, Tsinghua University
  • Jens Eisert, Free University of Berlin
  • Glen Evenbly, University of Sherbrooke
  • Tobias Hartung, Deutsches Elektronen-Synchrotron
  • Ling-Yan Hung, Fudan University
  • Simone Montangero, Padova University
  • Subir Sachdev, Harvard University
  • Tadashi Takayanagi, Yukawa Institute for Theoretical Physics
  • Frank Verstraete, University of Vienna & University of Ghent
  • Michael Walter, University of Amsterdam
  • Steven White, University of California, Irvine
  • Yijian Zou, X, the Moonshot Factory

 

 

 

Friday Nov 20, 2020
Speaker(s): 

We present some recent results on the development of efficient unconstrained tree tensor networks algorithms and their application to high-dimensional many-body quantum systems. In particular, we present our results on topological two-dimensional systems, two-dimensional Rydberg atom systems, and two- and three-dimensional lattice gauge theories in presence of fermonic matter.

Scientific Areas: 
 

 

Friday Nov 20, 2020
Speaker(s): 

In this talk we will start with a review of path-integraloptimization, which provides a useful description of non-unitary tensor networks for Euclidean path-integrals in CFTs. We will explain an emergence of AdS geometry in this method and an interpretation as a computational complexity. Next we will give its application to analytical calculations of entanglement of purification, which was quite recently reproduced by numerical calculations. Finally, we would like to present a derivation of a path-integral optimization method directly from the AdS/CFT.

Scientific Areas: 
 

 

Thursday Nov 19, 2020
Speaker(s): 

In this talk I will speak about the meeting point of two models that have raised interest in the community in the last years. From one side, we looked at measurement-based quantum computing (MBQC), which is an alternative to circuit-based quantum computing. Instead of modifying a state via gates, MBQC achieves the same result by measuring auxiliary qubits in a graph. From the other side, we considered variational quantum eigensolvers (VQEs), that are one of the most successful tools for exploiting quantum computers in the NISQ era. In our work, we present two measurement-based VQE schemes.

Scientific Areas: 
 

 

Thursday Nov 19, 2020
Speaker(s): 

A quantum state is a map from operators to real numbers that are their expectation values. Evaluating this map always entails using some algorithm, for example contracting a tensor network. I propose a novel way of quantifying the complexity of a quantum state in terms of "query complexity": the number of times an efficient algorithm for computing correlation functions in the given state calls a certain subroutine. I construct such an algorithm for a general "state at a cutoff" in 1+1-dimensional field theory.

Scientific Areas: 
 

 

 

 

Wednesday Nov 18, 2020
Speaker(s): 

"Besides tensor networks, quantum computations (QC) as well use a Hamiltonian formulation to solve physical problems. Although QC are presently very limited, since only small number of qubits are available, they have the principal advantage that they straightforwardly scale to higher dimensions. A standard tool in the QC approach are Variational Quantum Simulations (VQS) which form a class of hybrid quantum-classical algorithms for solving optimization problems. For example, the objective may be to find the ground state of a Hamiltonian by minimizing the energy.

Scientific Areas: 
 

 

Wednesday Nov 18, 2020
Speaker(s): 

In contrast to the 4D case, there are well understood theories of quantum gravity for the 3D case. Indeed, 3D general relativity constitutes a topological field theory (of BF or equivalently Chern-Simons type) and can be quantized as such. The resulting quantum theory of gravity offers many interesting lessons for the 4D case.

Scientific Areas: 
 

 

Wednesday Nov 18, 2020
Speaker(s): 

The success of the Ryu-Takayanagi formula suggests a profound connection between the AdS/CFT correspondence and tensor networks.
There are since many works on constructing examples, although it is very difficult to make them explicit and quantitative. We will discuss some new progress in the toy example of p-adic CFT where its tensor network dual was previously constructed explicitly [ arXiv:1703.05445 , arXiv:1812.06059, arXiv:1902.01411], and how some analogue of Einstein equation on the graph emerges as we consider RG flow of these CFTs.

Scientific Areas: 
 

 

Tuesday Nov 17, 2020
Speaker(s): 

The search for applications of quantum computers has highlighted the field of quantum chemistry, where one can also apply tensor network methods. There are several challenges in getting useful results for molecules compared to simulating a model Hamiltonian in condensed matter physics. The first issue is in descretizing continuum space to get a finite Hamiltonian which is amenable to tensor network techniques. Another is the need for high accuracy, particularly in energies, to compare with experiments.

Scientific Areas: 
 

 

Tuesday Nov 17, 2020
Speaker(s): 

Multi-scale tensor networks offer a way to efficiently represent ground states of critical systems and may be adapted for state-preparation on a quantum computer. The tensor network for a single scale specifies a quantum channel whose fixed-point is a subregion of the approximate critical ground state. The fixed-point of a noisy channel is perturbed linearly in the noise parameter from the ideal state, making local observables stable against errors for these iterative algorithms.

Scientific Areas: 

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Scientific Organizers:

  • Lena Funcke, Perimeter Institute
  • Michal Heller, Max Planck Institute for Gravitational Physics
  • Karl Jansen, Deutsches Elektronen-Synchrotron
  • Stefan Kühn, The Cyprus Institute
  • Volker Schomerus, Deutsches Elektronen-Synchrotron
  • Sukhbinder Singh, Max Planck Institute for Gravitational Physics