2,673 research outputs found
Superqubits
We provide a supersymmetric generalization of n quantum bits by extending the
local operations and classical communication entanglement equivalence group
[SU(2)]^n to the supergroup [uOSp(1|2)]^n and the stochastic local operations
and classical communication equivalence group [SL(2,C)]^n to the supergroup
[OSp(1|2)]^n. We introduce the appropriate supersymmetric generalizations of
the conventional entanglement measures for the cases of and . In
particular, super-Greenberger-Horne-Zeilinger states are characterized by a
nonvanishing superhyperdeterminant.Comment: 16 pages, 4 figures, 4 tables, revtex; minor corrections, version
appearing in Phys. Rev.
Wrapped branes as qubits
Recent work has established a correspondence between the tripartite
entanglement measure of three qubits and the macroscopic entropy of the
four-dimensional 8-charge STU black hole of supergravity. Here we consider the
configurations of intersecting D3-branes, whose wrapping around the six compact
dimensions T^6 provides the microscopic string-theoretic interpretation of the
charges, and associate the three-qubit basis vectors |ABC>, (A,B,C=0 or 1) with
the corresponding 8 wrapping cycles. In particular, we relate a well-known fact
of quantum information theory, that the most general real three-qubit state can
be parameterized by four real numbers and an angle, to a well-known fact of
string theory, that the most general STU black hole can be described by four
D3-branes intersecting at an angle.Comment: Version appearing in Phys. Rev. Lett, includes Type IIA description
as well as Type II
Vacuum interpolation in supergravity via super p-branes
We show that many of the recently proposed supersymmetric p-brane solutions
of d=10 and d=11 supergravity have the property that they interpolate between
Minkowski spacetime and a compactified spacetime, both being supersymmetric
supergravity vacua. Our results imply that the effective worldvolume action for
small fluctuations of the super p-brane is a supersingleton field theory for
, as has been often conjectured in the past.Comment: 8p
Four-qubit entanglement from string theory
We invoke the black hole/qubit correspondence to derive the classification of
four-qubit entanglement. The U-duality orbits resulting from timelike reduction
of string theory from D=4 to D=3 yield 31 entanglement families, which reduce
to nine up to permutation of the four qubits.Comment: 4 pages, 1 figure, 2 tables, revtex; minor corrections, references
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Black Holes, Qubits and Octonions
We review the recently established relationships between black hole entropy
in string theory and the quantum entanglement of qubits and qutrits in quantum
information theory. The first example is provided by the measure of the
tripartite entanglement of three qubits, known as the 3-tangle, and the entropy
of the 8-charge STU black hole of N=2 supergravity, both of which are given by
the [SL(2)]^3 invariant hyperdeterminant, a quantity first introduced by Cayley
in 1845. There are further relationships between the attractor mechanism and
local distillation protocols. At the microscopic level, the black holes are
described by intersecting D3-branes whose wrapping around the six compact
dimensions T^6 provides the string-theoretic interpretation of the charges and
we associate the three-qubit basis vectors, |ABC> (A,B,C=0 or 1), with the
corresponding 8 wrapping cycles. The black hole/qubit correspondence extends to
the 56 charge N=8 black holes and the tripartite entanglement of seven qubits
where the measure is provided by Cartan's E_7 supset [SL(2)]^7 invariant. The
qubits are naturally described by the seven vertices ABCDEFG of the Fano plane,
which provides the multiplication table of the seven imaginary octonions,
reflecting the fact that E_7 has a natural structure of an O-graded algebra.
This in turn provides a novel imaginary octonionic interpretation of the 56=7 x
8 charges of N=8: the 24=3 x 8 NS-NS charges correspond to the three imaginary
quaternions and the 32=4 x 8 R-R to the four complementary imaginary octonions.
N=8 black holes (or black strings) in five dimensions are also related to the
bipartite entanglement of three qutrits (3-state systems), where the analogous
measure is Cartan's E_6 supset [SL(3)]^3 invariant.Comment: Version to appear in Physics Reports, including previously omitted
new results on small STU black hole charge orbits and expanded bibliography.
145 pages, 15 figures, 41 table
Legal coercion, respect & reason-responsive agency
Legal coercion seems morally problematic because it is susceptible to the Hegelian objection that it fails to respect individuals in a way that is âdue to them as menâ. But in what sense does legal coercion fail to do so? And what are the grounds for this requirement to respect? This paper is an attempt to answer these questions. It argues that (a) legal coercion fails to respect individuals as reason-responsive agents; and (b) individuals ought to be respected as such in virtue of the fact that they are human beings. Thus it is in this sense that legal coercion fails to treat individuals with the kind of respect âdue to them as menâ.The Leverhulme Trust (ECF-2012-032); AHRC (AH/H015655/1
Generating branes via sigma-models
Starting with the D-dimensional Einstein-dilaton-antisymmetric form equations
and assuming a block-diagonal form of a metric we derive a -dimensional
-model with the target space or its non-compact form. Various solution-generating techniques are
developed and applied to construct some known and some new -brane solutions.
It is shown that the Harrison transformation belonging to the
subgroup generates black -branes from the seed Schwarzschild solution. A
fluxbrane generalizing the Bonnor-Melvin-Gibbons-Maeda solution is constructed
as well as a non-linear superposition of the fluxbrane and a spherical black
hole. A new simple way to endow branes with additional internal structure such
as plane waves is suggested. Applying the harmonic maps technique we generate
new solutions with a non-trivial shell structure in the transverse space
(`matrioshka' -branes). It is shown that the -brane intersection rules
have a simple geometric interpretation as conditions ensuring the symmetric
space property of the target space. Finally, a Bonnor-type symmetry is used to
construct a new magnetic 6-brane with a dipole moment in the ten-dimensional
IIA theory.Comment: 21 pages Late
Twenty Years of the Weyl Anomaly
In 1973 two Salam prot\'{e}g\'{e}s (Derek Capper and the author) discovered
that the conformal invariance under Weyl rescalings of the metric tensor
displayed by classical
massless field systems in interaction with gravity no longer survives in the
quantum theory. Since then these Weyl anomalies have found a variety of
applications in black hole physics, cosmology, string theory and statistical
mechanics. We give a nostalgic review. (Talk given at the {\it Salamfest},
ICTP, Trieste, March 1993.)Comment: 43 page
Pilgrimâs Progress: Lessons in Shared Governance
In the Spring of 2006, Southern Illinois University Edwardsville (SIUE) initiated a conversation to define a âTeacher-Scholarâ Philosophy appropriate for the campus. In an experience similar to John Bunyanâs protagonist, Christian, in the classic 1678 allegory Pilgrimâs Progress, the SIUE faculty and administrators set off on a 21st century journey of discovery.[2] Our journey, however, was toward shared governance, rather than down the path to salvation. Like Bunyanâs Christian, we traveled metaphorically through the Town of Vanity, the Valley of Humiliation, the Slough of Despond, the Hill of Difficulty, and the Castle of Doubt. Unlike Christian, however, our journey of discovery ended before we crossed the River of Death and entered the Celestial City
Higher Structures in M-Theory
The key open problem of string theory remains its non-perturbative completion
to M-theory. A decisive hint to its inner workings comes from numerous
appearances of higher structures in the limits of M-theory that are already
understood, such as higher degree flux fields and their dualities, or the
higher algebraic structures governing closed string field theory. These are all
controlled by the higher homotopy theory of derived categories, generalised
cohomology theories, and -algebras. This is the introductory chapter
to the proceedings of the LMS/EPSRC Durham Symposium on Higher Structures in
M-Theory. We first review higher structures as well as their motivation in
string theory and beyond. Then we list the contributions in this volume,
putting them into context.Comment: 22 pages, Introductory Article to Proceedings of LMS/EPSRC Durham
Symposium Higher Structures in M-Theory, August 2018, references update
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