31,333 research outputs found
Fault-tolerant magic state preparation with flag qubits
Magic state distillation is one of the leading candidates for implementing
universal fault-tolerant logical gates. However, the distillation circuits
themselves are not fault-tolerant, so there is additional cost to first
implement encoded Clifford gates with negligible error. In this paper we
present a scheme to fault-tolerantly and directly prepare magic states using
flag qubits. One of these schemes uses a single extra ancilla, even with noisy
Clifford gates. We compare the physical qubit and gate cost of this scheme to
the magic state distillation protocol of Meier, Eastin, and Knill, which is
efficient and uses a small stabilizer circuit. In some regimes, we show that
the overhead can be improved by several orders of magnitude.Comment: 26 pages, 17 figures, 5 tables. Comments welcome! v2 (published
version): quantumarticle documentclass and expanded discussions on the
fault-tolerant scheme
Homosexuality and the Construction of âAnglican Orthodoxyâ : The Symbolic Politics of the Anglican Communion
Peer reviewedPostprin
Unique Quantum Stress Fields
We have recently developed a geometric formulation of the stress field for an
interacting quantum system within the local density approximation (LDA) of
density functional theory (DFT). We obtain a stress field which is invariant
with respect to choice of energy density. In this paper, we explicitly
demonstrate this uniqueness by deriving the stress field for different energy
densities. We also explain why particular energy densities give expressions for
the stress field that are more tractable than others, thereby lending
themselves more easily to first-principles calculations.Comment: To appear in Proceedings for Fundamental Physics of Ferroelectrics
(2001
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