457 research outputs found
Anomaly-induced dynamical refringence in strong-field QED
We investigate the impact of the Adler-Bell-Jackiw anomaly on the
nonequilibrium evolution of strong-field quantum electrodynamics (QED) using
real-time lattice gauge theory techniques. For field strengths exceeding the
Schwinger limit for pair production, we encounter a highly absorptive medium
with anomaly-induced dynamical refractive properties. In contrast to earlier
expectations based on equilibrium properties, where net anomalous effects
vanish because of the trivial vacuum structure, we find that out-of-equilibrium
conditions can have dramatic consequences for the presence of quantum currents
with distinctive macroscopic signatures. We observe an intriguing tracking
behavior, where the system spends longest times near collinear field
configurations with maximum anomalous current. Apart from the potential
relevance of our findings for future laser experiments, similar phenomena
related to the chiral magnetic effect are expected to play an important role
for strong QED fields during initial stages of heavy-ion collision experiments.Comment: 5 pages, 4 figures, references adde
Randomized measurement protocols for lattice gauge theories
Randomized measurement protocols, including classical shadows, entanglement
tomography, and randomized benchmarking are powerful techniques to estimate
observables, perform state tomography, or extract the entanglement properties
of quantum states. While unraveling the intricate structure of quantum states
is generally difficult and resource-intensive, quantum systems in nature are
often tightly constrained by symmetries. This can be leveraged by the
symmetry-conscious randomized measurement schemes we propose, yielding clear
advantages over symmetry-blind randomization such as reducing measurement
costs, enabling symmetry-based error mitigation in experiments, allowing
differentiated measurement of (lattice) gauge theory entanglement structure,
and, potentially, the verification of topologically ordered states in existing
and near-term experiments.Comment: 18 pages, 15 figure
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