11,533 research outputs found
A New Entropic Force Scenario and Holographic Thermodynamics
We propose a new holographic program of gravity in which we introduce a
surface stress tensor. Our proposal differs from Verlinde's in several aspects.
First, we use an open or a closed screen, a temperature is not necessary but a
surface energy density and pressure are introduced. The surface stress tensor
is proportional to the extrinsic curvature. The energy we use is Brown-York
energy and the equipartiton theorem is violated by a non-vanishing surface
pressure. We discuss holographic thermodynamics of a gas of weak gravity and
find a chemical potential, and show that Verlinde's program does not lead to a
reasonable thermodynamics. The holographic entropy is similar to the Bekenstein
entropy bound.Comment: 23 pages v2: typos correcte
Operator content and modular property of Chern-Simons coupled to a massless scalar
Corrected with some rewordin
A One Loop Problem of the Matrix Big Bang Model
We compute the one-loop effective action of two D0-branes in the matrix model
for a cosmological background, and find vanishing static potential. However,
there is a non-vanishing term not predicted in a supergravity
calculation. This term is complex and signals an instability of the two
D0-brane system, it may also indicate that the matrix model is incorrect.Comment: 21 pages, harvmac, v4: version to appear in JHE
Mathieu equation and Elliptic curve
We present a relation between the Mathieu equation and a particular elliptic
curve. We find that the Floquet exponent of the Mathieu equation, for both
, can be obtained from the integral of a differential one form
along the two homology cycles of the elliptic curve. Certain higher order
differential operators are needed to generate the WKB expansion. We provide a
fifth order proof.Comment: 12 pages; minor improvement of the Conclusion section, references
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Spin-orbit couplings between distant electrons trapped individually on liquid helium
We propose an approach to entangle spins of electrons floating on liquid
helium by coherently manipulating their spin-orbit interactions. The
configuration consists of single electrons, confined individually on liquid
helium by the microelectrodes, moving along the surface as the harmonic
oscillators. It has been known that the spin of an electron could be coupled to
its orbit (i.e., the vibrational motion) by properly applying a magnetic field.
Based on this single electron spin-orbit coupling, here we show that a
Jaynes-Cummings (JC) type interaction between the spin of an electron and the
orbit of another electron at a distance could be realized via the strong
Coulomb interaction between the electrons. Consequently, the proposed JC
interaction could be utilized to realize a strong orbit-mediated spin-spin
coupling and implement the desirable quantum information processing between the
distant electrons trapped individually on liquid helium.Comment: 12 pages, 4 figure
Coherently manipulating cold ions in separated traps by their vibrational couplings
Recent experiments [K. R. Brown, et al., Nature 471, 196 (2011); and M.
Harlander, et al., Nature 471, 200 (2011)] have demonstrated the coherent
manipulations on the external vibrations of two ions, confined individually in
the separated ion traps. Using these recently developed techniques, we propose
here an approach to realize the coherent operations, e.g., the universal
quantum gates, between the separated ion-trap qubits encoded by two internal
atomic states of the trapped ions. Our proposal operates beyond the usual
Lamb-Dicke limits, and could be applied to the scalable ion traps coupled by
their vibrations.Comment: 4 pages, 2 figure
Quantum Phase Transition of Bosons in a Shaken Optical Lattice
Recently, the lattice shaking technique has been used to couple different
Bloch bands resonantly. For the one-dimensional (1D) case, in which shaking is
along only one direction, experimental observation of domain-wall formation has
been explained by superfluid Ising transition. Inspired by these, we generalize
to a 2D case in which shaking is along two orthogonal directions. Analogous to
the 1D case, we find three different phases, the normal superfluid (NSF) phase,
the symmetry-breaking superfluid (SF) phase and the Mott insulator
(MI) phase. Furthermore, we demonstrate that the interaction effect induced by
inhomogeneous band mixing can modify the critical shaking amplitude. Unlike in
the 1D case, shaking types also can modify the critical shaking amplitude.
Unlike in the 1D case, shaking types also can modify the critical shaking
amplitude. We also construct a low-energy effective field theory to study the
quantum criticality of bosons near the tricritical point of NSF, SF and MI
phases. Moreover, we find a Bose liquid with anisotropically algebraic order
and propose to change the Bose-Einstein condensation (BEC) into a non-condensed
Bose liquid by tuning the shaking amplitude approaching the critical value.Comment: 11 pages, 7 figures, 2 tables; minor correction
Quantizing Strings in de Sitter Space
We quantize a string in the de Sitter background, and we find that the mass
spectrum is modified by a term which is quadratic in oscillating numbers, and
also proportional to the square of the Hubble constant.Comment: 13 pages. Version published in JHE
General explicit expressions for intertwining operators and direct rotations of two orthogonal projections
In this paper, based on the block operator technique and operator spectral
theory, the general explicit expressions for intertwining operators and direct
rotations of two orthogonal projections have been established. As a
consequence, it is an improvement of Kato's result (Perturbation Theory of
Linear operators, Springer-Verlag, Berlin/Heidelberg, 1996); J. Avron, R.
Seiler and B. Simon's Theorem 2.3 (The index of a pair of projections, J.
Funct. Anal. 120(1994) 220-237) and C. Davis, W.M. Kahan, (The rotation of
eigenvectors by a perturbation, III. SIAM J. Numer. Anal. 7(1970) 1-46)
The origin of entropy production in spacetime thermodynamics
We find that the ambiguity term of approximate Killing vector field is
responsible for the entropy production term. Without the ambiguity term, pure
Einstein theory and satisfy the relation of thermodynamic equilibrium.
Considering such an ambiguity term of approximate Killing vector field, we can
get the entropy production term and the entropy in with a form defined
by Jacobson. In pure Einstein theory, the shear term is the only geometric
contribution of entropy production term, while in it can also
contribute. We believe our approach and conclusion can be generalized to other
gravity theory.Comment: 8 pages, 0 figure
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