Report on an exchange visit to the library at Konstfack University College of Arts, Crafts and Design, Stockholm, Sweden, 9-15 May 2009

Report on an exchange visit to the library at Konstfack University College of Arts, Crafts and Design, Stockholm, Sweden, 9-15 May 200

All-optical generation of states for "Encoding a qubit in an oscillator"

Both discrete and continuous systems can be used to encode quantum information. Most quantum computation schemes propose encoding qubits in two-level systems, such as a two-level atom or an electron spin. Others exploit the use of an infinite-dimensional system, such as a harmonic oscillator. In "Encoding a qubit in an oscillator" [Phys. Rev. A 64 012310 (2001)], Gottesman, Kitaev, and Preskill (GKP) combined these approaches when they proposed a fault-tolerant quantum computation scheme in which a qubit is encoded in the continuous position and momentum degrees of freedom of an oscillator. One advantage of this scheme is that it can be performed by use of relatively simple linear optical devices, squeezing, and homodyne detection. However, we lack a practical method to prepare the initial GKP states. Here we propose the generation of an approximate GKP state by using superpositions of optical coherent states (sometimes called "Schr\"odinger cat states"), squeezing, linear optical devices, and homodyne detection.Comment: 4 pages, 3 figures. Submitted to Optics Letter

Transmission Of Optical Coherent State Qubits

We discuss the long distance transmission of qubits encoded in optical coherent states. Through absorption these qubits suffer from two main types of errors, the reduction of the amplitude of the coherent states and accidental application of the Pauli Z operator. We show how these errors can be fixed using techniques of teleportation and error correcting codes.Comment: Added two pages of explanation/background/review material to increase readability and clarity. Corrected minor typographical and linguistic error

Local Attempts to Ban Discrimination in Rental Housing against Families with Children: Avoiding the Preemption Barrier

This Comment analyzes the validity of local ordinances that have banned adults-only rental housing. The author argues that, although California has no legislation at the state level explicitly prohibiting landlords from discriminating against families with children, several of these local ordinances have been challenged on the grounds of state preemption. The author examines the sources and limitations of the power of local governments to enact ordinances of this nature and the California statues which address discrimination in housing, and concludes that the local ordinances are neither preempted by, nor in conflict with, existing state law