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Date Speaker Title
8 Oct 2021 Tobias Hartung (Bath) Zoom
Dimensional Expressivity Analysis for Parametric Quantum Circuits

A standard tool in quantum computing 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. As such, VQS use parametric quantum circuit designs to generate a family of quantum states (e.g., states obeying physical symmetries) and efficiently evaluate a cost function for the given set of variational parameters (e.g., energy of the current quantum state) on a quantum device. The optimization is then performed using a classical feedback loop based on the measurement outcomes of the quantum device. In the case of energy minimization, the optimal parameter set therefore encodes the ground state corresponding to the given Hamiltonian provided that the parametric quantum circuit is able to encode the ground state. Hence, the design of parametric quantum circuits is subject to two competing drivers. On one hand, the set of states, that can be generated by the parametric quantum circuit, has to be large enough to contain the ground state. On the other hand, the circuit should contain as few parametric quantum gates as possible to minimize noise from the quantum device. In other words, when designing a parametric quantum circuit we want to ensure that there are no redundant parameters. Thus, in this talk, I will introduce the dimensional expressivity analysis as a means of analyzing a given parametric design in order to remove redundant parameters as well as any unwanted symmetries. Time permitting, we may also discuss best-approximation errors for non-maximally expressive parametric quantum circuits or how to custom design parametric quantum circuits for specific physical applications in which physical states are restricted by a class of symmetries.

15 Oct 2021 Kristian Bredies (University of Graz, Austria) Zoom
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22 Oct 2021 Jingwei Liang (Shanghai Jiao Tong University, China) Zoom
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29 Oct 2021 Sebastian Banert (Lund, Sweden) Zoom
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5 Nov 2021 Jemma Shipton (Exeter) Zoom
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12 Nov 2021 Tony Shardlow (Bath) Zoom
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19 Nov 2021 Alex Bespalov (Birmingham) Zoom
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26 Nov 2021 Lisa Maria Kreusser (Bath) Zoom
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3 Dec 2021 Tatiana Bubba (Cambridge) Zoom
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10 Dec 2021 TBC Zoom
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17 Dec 2021 TBC Zoom
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Tips for giving talks

Tips for new students on giving talks

Since the audience of the NA seminar contains both PhD students and staff with quite wide interests and backgrounds, the following are some guidelines/hints to make sure people don't give you evil looks at lunch afterwards.

Before too much time passes in your talk, ideally the audience should know the answers to the following 4 questions:

  • What is the problem you're considering?
  • Why do you find this interesting?
  • What has been done before on this problem/what's the background?
  • What is your approach/what are you going to talk about?

There are lots of different ways to communicate this information. One way, if you're doing a slide show, could be for the first 4 slides to cover these 4 questions; although in this case you may want to revisit these points later on in the talk (e.g. to give more detail).

Remember:

  • "vertebrate style" (structure hidden inside - like the skeleton of a vertebrate) = good for detective stories, bad for maths talks.
  • "crustacean style" (structure visible from outside - like the skeleton of a crustacean) = bad for detective stories, good for maths talks.

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