quantum algorithms:
The hyperbolic pentagon code or HaPPY code is a quantum error correction code (a class of such codes really, indexed by a “cutoff” natural number) which is thought to exhibit characteristic properties akin to the encoding of bulk-quantum states by boundary-states expected in the AdS/CFT correspondence. In particular, the HaPPY code (or rather the tensor network that defines it) exhibits a discretized form of the Ryu-Takayanagi formula for holographic entanglement entropy.
Concretely, the the HaPPY code subspace is the image of the linear map formed by:
picking a perfect tensor $T$ of rank 6;
picking a finite cutoff of the pentagonal tesselation $\{5,4\}$ of the hyperbolic plane;
regarding its Poincaré dual graph as a tensor network (string diagram in finite-dimensional vector spaces) by
assigning $T$ to each vertex at the center of the pentagons (show in blue), with 5 of its indices contracted with its neighbours in the hyperbolic plane,
and its 6th uncontracted index remaining as an input (shown in red);
regading the uncontrated edges at the cutoff boundary as output (shown in white)
and thus as a linear map form the tensor product over the bulk-vertices to the tensor product over the edges sticking out over the boundary.
Tha HaPPY code is due to
following a precursor observation in
Review in:
See also:
Last revised on May 6, 2021 at 04:20:55. See the history of this page for a list of all contributions to it.