QUROPE Quantum Information Processing and Communication in Europe

Harnessing nonlinearities strong enough to allow two single photons to interact with one another is not only a fascinating challenge but is central to numerous advanced applications in quantum information science. Currently, all known approaches are extremely challenging although a few have led to experimental realisations with attenuated classical laser light.

We show how to use the radiation pressure optomechanical coupling between a mechanical oscillator and an optical cavity field to generate in a heralded way a single quantum of mechanical motion (a Fock state). Starting with the oscillator close to its ground state, a laser pumping the upper motional sideband produces correlated photon-phonon pairs via optomechanical parametric down-conversion.

Monitoring a mechanical object’s motion, even with the gentle touch of light, fundamentally alters its dynamics.

Entangled quantum systems have properties that have fundamentally overthrown the classical worldview. Increasing the complexity of entangled states by expanding their dimensionality allows the implementation of novel fundamental tests of nature, and moreover also enables genuinely new protocols for quantum information processing.

The steady increase in control over individual quantum systems has backed the dream of a quantum technology that provides functionalities beyond any classical device. Two particularly promising applications have been explored during the past decade: First, photon-based quantum communication, which guarantees unbreakable encryption but still has to be scaled to high rates over large distances. Second, quantum computation, which will fundamentally enhance computability if it can be scaled to a large number of quantum bits.

2013, 9-14 june; Varenna, Italy; http://www.atomoptic.fr/varenna2013/

• Tilman Esslinger (ETHZ) Talk: Conduction between two reservoirs: disorder and interactions

2014 March 9-12; Heidelberg, Germany; http://emergence2014.uni-hd.de/

• Tilman Esslinger (ETHZ) talk: From Terminal to Terminal with Atoms

2014 April 28 - May 03; Capri, Italy; http://tfp1.physik.uni-freiburg.de/Capri14/

• Sebastian Krinner (ETHZ) talk: "Quantized conductance in Neutral Matter"

2014 March 31 - April 04; Barcelona, Spain; http://yao2014.icfo.es/

• Dominik Husman (ETHZ), talk: "Quantised conductance in Neutral Matter"

In transport experiments the quantum nature of matter becomes directly evident when changes in conductance occur only in discrete steps, with a size determined solely by Planck's constant h. The observations of quantized steps in the electric conductance have provided important insights into the physics of mesoscopic systems and allowed for the development of quantum electronic devices. Even though quantized conductance should not rely on the presence of electric charges, it has never been observed for neutral, massive particles.