Non-trivial Area Operators Require Non-local Magic

TL;DR

This paper proves that stabilizer and certain quantum codes cannot support non-trivial area operators locally, implying non-local 'magic' is essential for modeling aspects of gravity and quantum extremal surfaces.

Contribution

It establishes a no-go theorem for local area operators in stabilizer codes and related quantum codes, highlighting the necessity of non-local features for gravitational modeling.

Findings

Stabilizer codes cannot support non-trivial local area operators.

The no-go result extends to codes with certain logical operator factorizations.

Some non-stabilizer codes can have non-trivial area operators.

Abstract

We show that no stabilizer codes over any local dimension can support a non-trivial area operator for any bipartition of the physical degrees of freedom even if certain code subalgebras contain non-trivial centers. This conclusion also extends to more general quantum codes whose logical operators satisfy certain factorization properties, including any complementary code that encodes qubits and supports transversal logical gates that form a nice unitary basis. These results support the observation that some desirable conditions for fault tolerance are in tension with emergent gravity and suggest that non-local "magic" would play an important role in reproducing features of gravitational back-reaction and the quantum extremal surface formula. We comment on conditions needed to circumvent the no-go result and examine some simple instances of non-stabilizer codes that do have non-trivial area operators.