Listen to Professor Jan-Åke Larssons talk at the Cavendish Quantum Information Seminar Series, on what gives advantages to quantum algorithms.

The seminar with the title “Quantum computation and the additional degrees of freedom in a physical system” was held this fall.

The speed-up of Quantum Computers is the current drive of an entire scientific field with several large research programmes both in industry and academia world-wide. Many of these programmes are intended to build hardware for quantum computers.

A related important goal is to understand the reason for quantum computational speed-up; to understand what resources are provided by the quantum system used in quantum computation. Some candidates for such resources include superposition and interference, entanglement, nonlocality, contextuality, and the continuity of state-space. The standard approach to these issues is to restrict quantum mechanics and characterize the resources needed to restore the advantage.

Our approach is dual to that, instead extending a classical information processing systems with additional properties in the form of additional degrees of freedom, normally only present in quantum-mechanical systems.

In this talk, we will have a look at these additional degrees of freedom including the effect of Pauli-group contextuality, and how quantum computers make use of them to achieve the quantum speedup.

[1] Christoffer Hindlycke, Jan-Åke Larsson, An efficient contextual ontological model of n-qubit stabilizer quantum mechanics, to appear in Phys Rev Lett (2022).
[2] Niklas Johansson, Felix Huber, Jan-Åke Larsson, Conjugate Logic (2021).
[3] Niklas Johansson, Jan-Åke Larsson, Quantum Simulation Logic, Oracles, and the Quantum Advantage, Entropy 21:800 (2019).

Jan-Åke Larsson.

Nobel Prize awarded for evidence of entangled particles

The Nobel Prize for Physics, 2022, has been awarded to three researchers, for their research into quantum phenomena. Jan-Åke Larsson, professor at LiU, has made theoretical contributions to experiments led by Anton Zeilinger in Vienna.

Quantum computers and photonics to attract students

“We have seen increasing interest from students for quantum computers, quantum cryptography and photonics, says Jan-Åke Larsson, who has taken the initiative to a new profile within Applied Physics and Electrical Engineering.

Jan-Åke Larsson

Spreading light over quantum computers

Scientists at Linköping University have managed to simulate quantum computer properties in a classical computer. “Our results should be highly significant in determining how to build quantum computers”, says Professor Jan-Åke Larsson.

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