Quantum Information Processing
Abstract
We have made progress on many fronts on the understanding and characterization of entanglement. Various new forms of bound (i.e. undistillable) entanglement have been introduced, as part of our work on unextendable product states. Cases of "superactivation" of bound entanglement, in which two different bound entangled states, when joined, produce distillable entanglement, have been established for fourparty states and have been conjectured for bipartite states. These results show that the distillable entanglement is neither additive nor convex -- this achieves one of the major three year goals of this project. An explicit formula for the entanglement of formation was found for all isotropic mixed states. We discovered and characterized "remote state preparation", a generalization of quantum entanglement in which the transmitted quantum state is known to Alice. Very recently, with A. Winter, a new, more efficient protocol for RSP has been discovered. We have continued to study many ideas for the simplification of the Kane approach to quantum computing, with the replacement of electron spin for nuclear spin. Important simplifications over the currently published device designs will be possible. We have worked out a scheme for the implementation of quantum computing, building on the theory of decoherence-free subspaces, that uses only the Heisenberg exchange interaction, or only the XY interaction. We have provided detailed calculations of how g-factor engineering could be realized in III-V semiconductor heterostructures. We have shown how to ameliorate the effects of spin orbit interaction in quantum-dot qubits. We have begun master-equation modeling of superconducting qubits.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 02, 2001
- Accession Number
- ADA414217
Entities
People
- Charles H. Bennett
- David P. DiVincenzo
Organizations
- IBM Thomas J. Watson Research Center