Homological Quantum Rotor Codes: Logical Qubits from Torsion

Fuente: arXiv
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Autores principales: Vuillot, Christophe, Ciani, Alessandro, Terhal, Barbara M.
Formato: Preprint
Publicado: 2023
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author Vuillot, Christophe
Ciani, Alessandro
Terhal, Barbara M.
author_facet Vuillot, Christophe
Ciani, Alessandro
Terhal, Barbara M.
contents We formally define homological quantum rotor codes which use multiple quantum rotors to encode logical information. These codes generalize homological or CSS quantum codes for qubits or qudits, as well as linear oscillator codes which encode logical oscillators. Unlike for qubits or oscillators, homological quantum rotor codes allow one to encode both logical rotors and logical qudits in the same block of code, depending on the homology of the underlying chain complex. In particular, a code based on the chain complex obtained from tessellating the real projective plane or a Möbius strip encodes a qubit. We discuss the distance scaling for such codes which can be more subtle than in the qubit case due to the concept of logical operator spreading by continuous stabilizer phase-shifts. We give constructions of homological quantum rotor codes based on 2D and 3D manifolds as well as products of chain complexes. Superconducting devices being composed of islands with integer Cooper pair charges could form a natural hardware platform for realizing these codes: we show that the $0$-$π$-qubit as well as Kitaev's current-mirror qubit -- also known as the Möbius strip qubit -- are indeed small examples of such codes and discuss possible extensions.
format Preprint
id arxiv_https___arxiv_org_abs_2303_13723
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Homological Quantum Rotor Codes: Logical Qubits from Torsion
Vuillot, Christophe
Ciani, Alessandro
Terhal, Barbara M.
Quantum Physics
We formally define homological quantum rotor codes which use multiple quantum rotors to encode logical information. These codes generalize homological or CSS quantum codes for qubits or qudits, as well as linear oscillator codes which encode logical oscillators. Unlike for qubits or oscillators, homological quantum rotor codes allow one to encode both logical rotors and logical qudits in the same block of code, depending on the homology of the underlying chain complex. In particular, a code based on the chain complex obtained from tessellating the real projective plane or a Möbius strip encodes a qubit. We discuss the distance scaling for such codes which can be more subtle than in the qubit case due to the concept of logical operator spreading by continuous stabilizer phase-shifts. We give constructions of homological quantum rotor codes based on 2D and 3D manifolds as well as products of chain complexes. Superconducting devices being composed of islands with integer Cooper pair charges could form a natural hardware platform for realizing these codes: we show that the $0$-$π$-qubit as well as Kitaev's current-mirror qubit -- also known as the Möbius strip qubit -- are indeed small examples of such codes and discuss possible extensions.
title Homological Quantum Rotor Codes: Logical Qubits from Torsion
topic Quantum Physics
url https://arxiv.org/abs/2303.13723