  Embezzlement of entanglement refers to the counterintuitive possibility of
extracting entangled quantum states from a reference state of an auxiliary
system (the "embezzler") via local quantum operations while hardly perturbing
the latter. We uncover a deep connection between the operational task of
embezzling entanglement and the mathematical classification of von Neumann
algebras. Our result implies that relativistic quantum fields are universal
embezzlers: Any entangled state of any dimension can be embezzled from them
with arbitrary precision. This provides an operational characterization of the
infinite amount of entanglement present in the vacuum state of relativistic
quantum field theories.
