QUROPE Quantum Information Processing and Communication in Europe

The Information Day - FP7-Call-9 took place on 18 Jan 2012 in Brussels and was attended by some ~250 people. The slides of the presentation are available for download from the Info Day Agenda.

We consider whether or not Hamiltonians which are sums of commuting projectors have "trivial" ground states which can be constructed by a local quantum circuit of bounded depth and range acting on a product state. While the toric code only has nontrivial ground states, commuting projector Hamiltonians which are sums of two-body interactions have trivial ground states.

A big open question in the quantum information theory concerns feasibility of a self-correcting quantum memory. A quantum state recorded in such memory can be stored reliably for a macroscopic time without need for active error correction if the memory is put in contact with a cold enough thermal bath. In this paper we derive a rigorous lower bound on the memory time $T_{mem}$ of the 3D Cubic Code model which was recently conjectured to have a self-correcting behavior.

The press release is available at the following link: http://www.mpq.mpg.de/cms/mpq/en/news/press/11_10_14.html

The link to the paper is the following: http://dx.doi.org/10.1126/science.1209284

Current attempts to probe general relativistic effects in quantum mechanics focus on precision measurements of phase shifts in matter–wave interferometry. Yet, phase shifts can always be explained as arising because of an Aharonov–Bohm effect, where a particle in a flat space–time is subject to an effective potential. Here we propose a quantum effect that cannot be explained without the general relativistic notion of proper time.

physics.aps.org/viewpoint-for/10.1103/PhysRevLett.107.12050

Prof. Dan Browne from the University College London in the newest issue of APS Physics writes about the QEssence's researchers latest discovery (prl.aps.org/abstract/PRL/v107/i12/e120501) that using a quantum computer to simulate another quantum system will work even when the modeled system is not isolated from its environment.

We show that the time evolution of an open quantum system, described by a possibly time dependent Liouvillian, can be simulated by a unitary quantum circuit of a size scaling polynomially in the simulation time and the size of the system. An immediate consequence is that dissipative quantum computing is no more powerful than the unitary circuit model.

The QUIE2T-sponsored international conference on Quantum Information Processing and Communication (QIPC 2011) was held at ETH Zurich from September 5 - 9, 2011.

A detailed report on the conference is attached, see link  below.

The von Neumann architecture for a classical computer comprises a central processing unit and a memory holding instructions and data. We demonstrate a quantum central processing unit that exchanges data with a quantum random-access memory integrated on a chip, with instructions stored on a classical computer. We test our quantum machine by executing codes that involve seven quantum elements: Two superconducting qubits coupled through a quantum bus, two quantum memories, and two zeroing registers.

Read more at the link: http://www.mpq.mpg.de/cms/mpq/en/news/awards/11_08_02.html