5,464 research outputs found
Asymmetric Quantum Codes: New Codes from Old
In this paper we extend to asymmetric quantum error-correcting codes (AQECC)
the construction methods, namely: puncturing, extending, expanding, direct sum
and the (u|u + v) construction. By applying these methods, several families of
asymmetric quantum codes can be constructed. Consequently, as an example of
application of quantum code expansion developed here, new families of
asymmetric quantum codes derived from generalized Reed-Muller (GRM) codes,
quadratic residue (QR), Bose-Chaudhuri-Hocquenghem (BCH), character codes and
affine-invariant codes are constructed.Comment: Accepted for publication Quantum Information Processin
A dual 2D model for the Quantum Hall Fluid
We present a dual two dimensional model for the Quantum Hall Fluid depending
on two parameters and show that this model has topologically non-trivial vacua
which are infrared stable fixed points of the Renormalization Group. The model
has a discrete (modular) symmetry which reproduces the fenomenological law of
corresponding states and allows for an unified description of the critical
points corresponding to Hall plateaus in terms of a 2 dimensional Conformal
Field Theory.Comment: 10 pages, Revtex, no figure
Optimal purification of a generic n-qudit state
We propose a quantum algorithm for the purification of a generic mixed state
of a -qudit system by using an ancillary -qudit system. The
algorithm is optimal in that (i) the number of ancillary qudits cannot be
reduced, (ii) the number of parameters which determine the purification state
exactly equals the number of degrees of freedom of , and (iii)
is easily determined from the density matrix . Moreover, we
introduce a quantum circuit in which the quantum gates are unitary
transformations acting on a -qudit system. These transformations are
determined by parameters that can be tuned to generate, once the ancillary
qudits are disregarded, any given mixed -qudit state.Comment: 8 pages, 9 figures, remarks adde
Global Regulatory Standards and Secured Transactions Law Reforms: At the Crossroad Between Access to Credit and Financial Stability
Credit Creation: Reconciling Legal and Regulatory Incentives
As international organizations adopt new legal standards to promote access to credit through the modernization of national secured transactions law, the lack of coordination with regulatory standards for banking institutions thwarts the effectiveness of these efforts. In recognizing the relevance of the problem, UNCITRAL - for the first time since its establishment - is currently considering how to coordinate secured transactions law reforms with the implementation of the Basel Accord. In a similar vein, the problem is currently approached by other international organisations. Although efforts at the national level to coordinate legal and regulatory standards are commendable, coordination between secured transactions law and capital requirements should be addressed at the highest level of the lawmaking process, i.e. when international soft-laws are defined. To advance this argument, the key functions of secured transactions law and capital requirements are isolated and a holistic understanding of the legal and regulatory rules governing the creation of credit is presented. The Article steers away from the idea that banks are mere intermediaries and offers a fresh understanding of the role of regulatory capital in controlling credit creation, through the management of risk. Within this context, the incentives created by secured transactions law and capital requirements are examined by comparing the capital charges for different credit protections, including credit derivatives and commercial loans to small business. First, it emerges that the implementation of new secured transactions law and the limited ability of security interests in personal property to reduce regulatory capital under the Basel Accords stimulate the creation of credit outside the banking system. Second, to control this phenomenon, the Article shows that it is essential to reconcile the incentive structures created by international legal and regulatory standards
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