Lattice subsystem code[1]
Alternative names: Topological subsystem code.
Description
A geometrically local qubit, modular-qudit, or Galois-qudit subsystem stabilizer code with qudits organized on a lattice modeled by the additive group \(\mathbb{Z}^D\) for spatial dimension \(D\). On an infinite lattice, its gauge and stabilizer groups are generated by few-site Pauli operators and their translations, in which case the code is called translationally invariant subsystem code. Boundary conditions have to be imposed on the lattice in order to obtain finite-dimensional versions, in which case the stabilizer group may no longer be generated by few-site Pauli operators. Lattice defects and boundaries between different codes can also be introduced. Lattice subsystem stabilizer code Hamiltonians described by an Abelian anyon theory do not always realize the corresponding anyonic topological order in their ground-state subspace and may exhibit a rich phase diagram.Rate
Subsystem BT bound: Subsystem qubit stabilizer code parameters on \(D\)-dimensional Euclidean lattices are limited by the subsystem Bravyi-Terhal (BT) bound [2], which states that \(d = O(n^{1-1/D})\) and that \(k d^{1/(D-1)} = O(n)\) (using asymptotic notation). The second equation is different from the (subspace) BPT bound. In particular, \(D=2\)-dimensional subsystem codes satisfy \(kd = O(n)\) [3]. More generally, there is a tradeoff theorem [4] stating that, for any logical operator, there is an equivalent logical operator with weight \(\tilde{d}\) such that \(\tilde{d}d^{1/(D-1)}=O(L^{D})\).
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Gates
Subsystem PYBK bound: The Bravyi-Koenig bound can be extended to subsystem codes by Pastawski and Yoshida. Namely, logical gates implemented via constant-depth quantum circuits on a \(D\)-dimensional lattice subsystem code whose distance increases at least logarithmically with \(n\) lie in the \(D\)th level of the Clifford hierarchy [5].
Cousins
- Lattice stabilizer code— Lattice subsystem codes reduce to lattice stabilizer codes when there are no gauge qudits. The former (latter) is required to admit few-site gauge-group (stabilizer-group) generators on a lattice with boundary conditions.
- Abelian topological code— All 2D Abelian bosonic topological orders can be realized as modular-qudit lattice subsystem codes by starting with an Abelian quantum double model (slightly different from that of Ref. [6]) along with a family of Abelian TQDs that generalize the double semion anyon theory and gauging out certain bosonic anyons [7]. The stabilizer generators of the new subsystem code may no longer be geometrically local. Lattice subsystem stabilizer code Hamiltonians described by an Abelian anyon theory do not always realize the corresponding anyonic topological order in their ground-state subspace and may exhibit a rich phase diagram. Non-Abelian topological orders are purported not to be realizable with Pauli stabilizer codes [8].
- Good QLDPC code— An \([[n,k,d]]\) qubit stabilizer code can be converted into an order \([[O(\ell \delta n),k,\Omega(d/w)]]\) subsystem qubit stabilizer code with weight-three gauge operators via the wire-code mapping [9], which uses weight reduction. Here, \(w\) and \(\delta\) are the weight and degree of the input code's Tanner graph, while \(\ell\) is the length of the longest edge of a particular embedding of that graph. Applying this procedure to good QLDPC codes and using an embedding into \(D\)-dimensional Euclidean space yields \([[n^{1-1/D},\Theta(n),\Theta(n)]]\) lattice subsystem codes that saturate the subsystem BT bound [9].
- Majorana subsystem stabilizer code— Translationally invariant subsystem codes have been formulated in terms of Majorana operators [10].
Primary Hierarchy
Parents
Lattice subsystem codes are sparse subsystem codes on Euclidean geometries.
Lattice subsystem code
Children
Modular-qudit subsystem color codes are defined analogous to qubit subsystem color codes on suitable lattices of any spatial dimension, but a directionality is required in order to make the modular-qudit stabilizers commute [11; Sec. VII].
References
- [1]
- H. Bombin, “Topological subsystem codes”, Physical Review A 81, (2010) arXiv:0908.4246 DOI
- [2]
- S. Bravyi and B. Terhal, “A no-go theorem for a two-dimensional self-correcting quantum memory based on stabilizer codes”, New Journal of Physics 11, 043029 (2009) arXiv:0810.1983 DOI
- [3]
- S. Bravyi, “Subsystem codes with spatially local generators”, Physical Review A 83, (2011) arXiv:1008.1029 DOI
- [4]
- J. Haah and J. Preskill, “Logical-operator tradeoff for local quantum codes”, Physical Review A 86, (2012) arXiv:1011.3529 DOI
- [5]
- F. Pastawski and B. Yoshida, “Fault-tolerant logical gates in quantum error-correcting codes”, Physical Review A 91, (2015) arXiv:1408.1720 DOI
- [6]
- T. D. Ellison, Y.-A. Chen, A. Dua, W. Shirley, N. Tantivasadakarn, and D. J. Williamson, “Pauli Stabilizer Models of Twisted Quantum Doubles”, PRX Quantum 3, (2022) arXiv:2112.11394 DOI
- [7]
- T. D. Ellison, Y.-A. Chen, A. Dua, W. Shirley, N. Tantivasadakarn, and D. J. Williamson, “Pauli topological subsystem codes from Abelian anyon theories”, Quantum 7, 1137 (2023) arXiv:2211.03798 DOI
- [8]
- A. C. Potter and R. Vasseur, “Symmetry constraints on many-body localization”, Physical Review B 94, (2016) arXiv:1605.03601 DOI
- [9]
- N. Baspin and D. Williamson, “Wire Codes”, (2024) arXiv:2410.10194
- [10]
- A. Chapman, S. T. Flammia, and A. J. Kollár, “Free-Fermion Subsystem Codes”, (2022) arXiv:2201.07254
- [11]
- F. H. E. Watson, E. T. Campbell, H. Anwar, and D. E. Browne, “Qudit color codes and gauge color codes in all spatial dimensions”, Physical Review A 92, (2015) arXiv:1503.08800 DOI
Page edit log
- Victor V. Albert (2024-01-30) — most recent
Cite as:
“Lattice subsystem code”, The Error Correction Zoo (V. V. Albert & P. Faist, eds.), 2024. https://errorcorrectionzoo.org/c/translationally_invariant_subsystem