What is it about?
We consider quantum circuit models from digital quantum computing which have been enriched with a conservation law, the conservation of total particle number in the system. We use these models to test fluctuating hydrodynamics, an effective theory for the dynamics of particle density at large scales, in a quantum setting. We consider these circuits in one dimension, and then study the transfer of these particles from left to right across the central of the system.
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Why is it important?
Initially introduced to describe classical fluids like air and water, it is widely believed that hydrodynamics also applies to quantum mechanical systems. This paper is the first test of fluctuating hydrodynamics, a universal theory of fluids at large scales, in a chaotic quantum system. We find that at long times, not only is the mean transport correctly captured by hydrodynamics in these systems, but so are the fluctuations. The entire distribution of particle transport is in agreement with classical hydrodynamic predictions. This is a precision test of hydrodynamic universality which goes beyond simple 'mean transport' measurements.
Perspectives
Few concepts in physics are as important as universality - the observation that completely different systems microscopically can share the same universal physics at large scales. To see this principle also borne out in a quantum system shows the power and wide applicability of effective theories.
Ewan McCulloch
Princeton University
Read the Original
This page is a summary of: Full Counting Statistics of Charge in Chaotic Many-Body Quantum Systems, Physical Review Letters, November 2023, American Physical Society (APS),
DOI: 10.1103/physrevlett.131.210402.
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