Pumping Chirality in Three Dimensions
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arXiv
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| Auteurs principaux: | , |
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| Format: | Preprint |
| Publié: |
2023
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| _version_ | 1866910703699361792 |
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| author | Fidkowski, Lukasz Hastings, Matthew B. |
| author_facet | Fidkowski, Lukasz Hastings, Matthew B. |
| contents | Using bosonization, which maps fermions coupled to a ${\mathbb{Z}}_2$ gauge field to a qubit system, we give a simple form for the non-trivial 3-fermion quantum cellular automaton (QCA) as a unitary operator realizing a phase depending on the framing of flux loops, building off work by Shirley et al. We relate this framing dependent phase to a pump of $8$ copies of a $p+ip$ state through the system. We give a resolution of an apparent paradox, namely that the pump is a shallow depth circuit (albeit with tails), while the QCA is nontrivial. We discuss also the pump of fewer copies of a $p+ip$ state, and describe its action on topologically degenerate ground states. One consequence of our results is that a pump of $n$ $p+ip$ states generated by a free Fermi evolution is a free fermion unitary characterized by a non-trivial winding number $n$ as a map from the third homotopy group of the Brilliouin Zone $3$-torus to that of $SU(N_ b)$, where $N_b$ is the number of bands. Using our simplified form of the QCA, we give higher dimensional generalizations that we conjecture are also nontrivial QCAs, and we discuss the relation to Chern-Simons theory. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2309_15903 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Pumping Chirality in Three Dimensions Fidkowski, Lukasz Hastings, Matthew B. Strongly Correlated Electrons Quantum Physics Using bosonization, which maps fermions coupled to a ${\mathbb{Z}}_2$ gauge field to a qubit system, we give a simple form for the non-trivial 3-fermion quantum cellular automaton (QCA) as a unitary operator realizing a phase depending on the framing of flux loops, building off work by Shirley et al. We relate this framing dependent phase to a pump of $8$ copies of a $p+ip$ state through the system. We give a resolution of an apparent paradox, namely that the pump is a shallow depth circuit (albeit with tails), while the QCA is nontrivial. We discuss also the pump of fewer copies of a $p+ip$ state, and describe its action on topologically degenerate ground states. One consequence of our results is that a pump of $n$ $p+ip$ states generated by a free Fermi evolution is a free fermion unitary characterized by a non-trivial winding number $n$ as a map from the third homotopy group of the Brilliouin Zone $3$-torus to that of $SU(N_ b)$, where $N_b$ is the number of bands. Using our simplified form of the QCA, we give higher dimensional generalizations that we conjecture are also nontrivial QCAs, and we discuss the relation to Chern-Simons theory. |
| title | Pumping Chirality in Three Dimensions |
| topic | Strongly Correlated Electrons Quantum Physics |
| url | https://arxiv.org/abs/2309.15903 |