19,502 research outputs found
Transition to Fulde-Ferrel-Larkin-Ovchinnikov phases near the tricritical point : an analytical study
We explore analytically the nature of the transition to the
Fulde-Ferrel-Larkin-Ovchinnikov superfluid phases in the vicinity of the
tricritical point, where these phases begin to appear. We make use of an
expansion of the free energy up to an overall sixth order, both in order
parameter amplitude and in wavevector. We first explore the minimization of
this free energy within a subspace, made of arbitrary superpositions of plane
waves with wavevectors of different orientations but same modulus. We show that
the standard second order FFLO phase transition is unstable and that a first
order transition occurs at higher temperature. Within this subspace we prove
that it is favorable to have a real order parameter and that, among these
states, those with the smallest number of plane waves are prefered. This leads
to an order parameter with a dependence, in
agreement with preceding work. Finally we show that the order parameter at the
transition is only very slightly modified by higher harmonics contributions
when the constraint of working within the above subspace is released.Comment: 11 pages, revte
Cavity squeezing by a quantum conductor
Hybrid architectures integrating mesoscopic electronic conductors with
resonant microwave cavities have a great potential for investigating unexplored
regimes of electron-photon coupling. In this context, producing nonclassical
squeezed light is a key step towards quantum communication with scalable
solid-state devices. Here we show that parametric driving of the electronic
conductor induces a squeezed steady state in the cavity. We find that squeezing
properties of the cavity are essentially determined by the electronic noise
correlators of the quantum conductor. In the case of a tunnel junction, we
predict that squeezing is optimized by applying a time-periodic series of
quantized peaks in the bias voltage. For an asymmetric quantum dot, we
show that a sharp Leviton pulse is able to achieve perfect cavity squeezing.Comment: 13 pages, 4 figures, includes Supplementary inf
On global location-domination in graphs
A dominating set of a graph is called locating-dominating, LD-set for
short, if every vertex not in is uniquely determined by the set of
neighbors of belonging to . Locating-dominating sets of minimum
cardinality are called -codes and the cardinality of an LD-code is the
location-domination number . An LD-set of a graph is global
if it is an LD-set of both and its complement . The global
location-domination number is the minimum cardinality of a
global LD-set of . In this work, we give some relations between
locating-dominating sets and the location-domination number in a graph and its
complement.Comment: 15 pages: 2 tables; 8 figures; 20 reference
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