7,975 research outputs found
On the mathematical foundations of mutually unbiased bases
In order to describe a setting to handle Zauner's conjecture on mutually unbiased bases (MUBs) (stating that in C-d, a set of MUBs of the theoretical maximal size d + 1 exists only if d is a prime power), we pose some fundamental questions which naturally arise. Some of these questions have important consequences for the construction theory of (new) sets of maximal MUBs. Partial answers will be provided in particular cases; more specifically, we will analyze MUBs with associated operator groups that have nilpotence class 2, and consider MUBs of height 1. We will also confirmZauner's conjecture forMUBswith associated finite nilpotent operator groups
Depicting qudit quantum mechanics and mutually unbiased qudit theories
We generalize the ZX calculus to quantum systems of dimension higher than
two. The resulting calculus is sound and universal for quantum mechanics. We
define the notion of a mutually unbiased qudit theory and study two particular
instances of these theories in detail: qudit stabilizer quantum mechanics and
Spekkens-Schreiber toy theory for dits. The calculus allows us to analyze the
structure of qudit stabilizer quantum mechanics and provides a geometrical
picture of qudit stabilizer theory using D-toruses, which generalizes the Bloch
sphere picture for qubit stabilizer quantum mechanics. We also use our
framework to describe generalizations of Spekkens toy theory to higher
dimensional systems. This gives a novel proof that qudit stabilizer quantum
mechanics and Spekkens-Schreiber toy theory for dits are operationally
equivalent in three dimensions. The qudit pictorial calculus is a useful tool
to study quantum foundations, understand the relationship between qubit and
qudit quantum mechanics, and provide a novel, high level description of quantum
information protocols.Comment: In Proceedings QPL 2014, arXiv:1412.810
SIC-POVMs and Compatibility among Quantum States
An unexpected connection exists between compatibility criteria for quantum
states and symmetric informationally complete POVMs. Beginning with Caves,
Fuchs and Schack's "Conditions for compatibility of quantum state assignments"
[Phys. Rev. A 66 (2002), 062111], I show that a qutrit SIC-POVM studied in
other contexts enjoys additional interesting properties. Compatibility criteria
provide a new way to understand the relationship between SIC-POVMs and mutually
unbiased bases, as calculations in the SIC representation of quantum states
make clear. This, in turn, illuminates the resources necessary for magic-state
quantum computation, and why hidden-variable models fail to capture the
vitality of quantum mechanics.Comment: 15 pages, 4 MUBs, 2 errata for CFS (2002), 1 graph with chromatic
number 4. v4: journal versio
MUBs: From finite projective geometry to quantum phase enciphering
This short note highlights the most prominent mathematical problems and
physical questions associated with the existence of the maximum sets of
mutually unbiased bases (MUBs) in the Hilbert space of a given dimensionComment: 5 pages, accepted for AIP Conf Book, QCMC 2004, Strathclyde, Glasgow,
minor correction
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