@Article{Zakka-Bajjani_etal2011,
author="Zakka-Bajjani, Eva
and Nguyen, Fran{\~A} ois
and Lee, Minhyea
and Vale, Leila R.
and Simmonds, Raymond W.
and Aumentado, Jos{\'e}",
title="Quantum superposition of a single microwave photon in two different {\textquoteright}colour{\textquoteright} states",
journal="Nature Physics",
year="2011",
volume="7",
number="8",
pages="599--603",
optkeywords="fromIPMRAS",
abstract="Fully controlled coherent coupling of arbitrary harmonic oscillators is an important tool for processing quantum information. Coupling between quantum harmonic oscillators has previously been demonstrated in several physical systems using a two-level system as a mediating element. Direct interaction at the quantum level has only recently been realized by means of resonant coupling between trapped ions. Here we implement a tunable direct coupling between the microwave harmonics of a superconducting resonator by means of parametric frequency conversion. We accomplish this by coupling the mode currents of two harmonics through a superconducting quantum interference device (SQUID) and modulating its flux at the difference ({\textasciitilde}7GHz) of the harmonic frequencies. We deterministically prepare a single-photon Fock state and coherently manipulate it between multiple modes, effectively controlling it in a superposition of two different {\textquoteright}colours{\textquoteright}. This parametric interaction can be described as a beamsplitter-like operation that couples different frequency modes. As such, it could be used to implement linear optical quantum computing protocols on-chip.",
optnote="exported from refbase (https://db.rplab.ru/refbase/show.php?record=822), last updated on Sat, 12 May 2012 14:59:40 -0500"
}