9,724 research outputs found
Interface Between Topological and Superconducting Qubits
We propose and analyze an interface between a topological qubit and a
superconducting flux qubit. In our scheme, the interaction between Majorana
fermions in a topological insulator is coherently controlled by a
superconducting phase that depends on the quantum state of the flux qubit. A
controlled phase gate, achieved by pulsing this interaction on and off, can
transfer quantum information between the topological qubit and the
superconducting qubit.Comment: 12 pages, 7 figures. V2: Final version as published in Phys. Rev.
Lett, with detailed clarifications in the Appendi
The Truth in Compatibilism and the truth of Libertarianism
The paper offers the outlines of a response to the often-made suggestion is that it is impossible to see how indeterminism could possibly provide us with anything that we might want in the way of freedom, anything that could really amount to control, as opposed merely to an openness in the flow of reality that would constitute merely the injection of chance, or randomness, into the unfolding of the processes which underlie our activity. It is suggested that the best first move for the libertarian is to make a number of important concessions to the compatibilist. It should be conceded, in particular, that certain sorts of alternative possibilities are neither truly available to real, worldly agents, nor required in order that those agents should act freely; and it should be admitted also that it is the compatibilist who tends to give the most plausible sorts of analyses of many of the ‘can’ and ‘could have’ statements which seem to need to be assertible of those agents we regard as free. But these concessions do not bring compatibilism itself in their wake. The most promising version of libertarianism, it is argued, should be based on the idea that agency itself (and not merely some special instances of it which we might designate with the honorific appellation ‘free’) is inconsistent with determinism. This version of libertarianism, it is claimed, can avoid the objection that indeterminism is as difficult to square with true agential control as determinism can sometimes seem to be
Self-duality in quantum impurity problems
We establish the existence of an exact non-perturbative self-duality in a
variety of quantum impurity problems, including the Luttinger liquid or quantum
wire with impurity. The former is realized in the fractional quantum Hall
effect, where the duality interchanges electrons with Laughlin quasiparticles.
We discuss the mathematical structure underlying this property, which bears an
intriguing resemblance with the work of Seiberg and Witten on supersymmetric
non-abelian gauge theory.Comment: 4 page
High-Field Electrical Transport in Single-Wall Carbon Nanotubes
Using low-resistance electrical contacts, we have measured the intrinsic
high-field transport properties of metallic single-wall carbon nanotubes.
Individual nanotubes appear to be able to carry currents with a density
exceeding 10^9 A/cm^2. As the bias voltage is increased, the conductance drops
dramatically due to scattering of electrons. We show that the current-voltage
characteristics can be explained by considering optical or zone-boundary phonon
emission as the dominant scattering mechanism at high field.Comment: 4 pages, 3 eps figure
- …