Theory seminar: Probing microcanonical ensemble properties on classical and quantum computers

Yilun Yang (MPQ)
It is hard to directly simulate the in-and-out-of-equilibrium behaviors of quantum many body systems in the long-time limit.

January 19, 2022

Yilun Yang (MPQ)
Group seminar (hybrid format: B0.32/Zoom)
Wed, 19 January 2022, 10:30 am (MEZ)
 

Abstract:

It is hard to directly simulate the in-and-out-of-equilibrium behaviors of quantum many body systems in the long-time limit. Alternatively, one can investigate the canonical and microcanonical ensembles, to decide whether the system thermalizes and to obtain thermal values of observables. While the canonical ensemble is easy to approximate with tensor network techniques, algorithms are developed recently to compute the microcanonical properties by applying filters which are narrow in energy. Specifically, the cosine filter is proposed as a quantum algorithm since it can be approximated by a series of evolution operators.

In this talk, I will introduce two ongoing works that implement the cosine filter on classical computers and NISQ quantum simulators respectively. I will focus on the first one, which is efficient (scalable to large systems) for 1D local Hamiltonians. Then for the second part, a brief introduction of current results and obstacles will follow.

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