ar X iv : q ua nt - p h / 06 11 14 4 v 1 1 4 N ov 2 00 6 Geometrical structure of entangled states and secant variety

ar X iv : q ua nt - p h / 04 11 17 2 v 1 2 3 N ov 2 00 4 Information and Entropy in Quantum Theory

ar X iv : q ua nt - p h / 06 11 05 0 v 1 6 N ov 2 00 6 The computational complexity of PEPS

We determine the computational power of preparing Projected Entangled Pair States (PEPS), as well as the complexity of classically simulating them, and generally the complexity of contracting tensor networks. While creating PEPS allows to solve PP problems, the latter two tasks are both proven to be #P-complete. We further show how PEPS can be used to approximate ground states of gapped Hamilto...

ar X iv : q ua nt - p h / 06 11 18 7 v 1 1 7 N ov 2 00 6 Philosophical Aspects of Quantum Information Theory

2 First steps with quantum information 3 2.1 Bits and qubits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 The no-cloning theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Quantum cryptography . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.3.1 Key Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4 Entanglement-as...

ar X iv : q ua nt - p h / 05 11 12 2 v 1 1 4 N ov 2 00 5 Continuum variable entangled state generated by an asymmetric beam

The generating entangled state by using a 50/50 beamsplitter has been discussed in the literature before . In this paper we explore how to use an asymmetric beam-splitter to produce a new kind of entangled state. We construct such kind of states theoretically and then prove that they make up a complete and orthonormal representation in two-mode Fock space. Its application in finding new squeezi...

ar X iv : q ua nt - p h / 06 08 21 9 v 2 1 5 N ov 2 00 6 Theoretical Study of Fast Light with Short sech Pulses in Coherent Gain Media

We investigate theoretically the phenomenon of so-called fast light in an unconventional regime, using pulses sufficiently short that relaxation effects in a gain medium can be ignored completely. We show that previously recognized gain instabilities, including superfluorescence, can be tolerated in achieving a pulse peak advance of one full peak width.