* Astronomy

More accurate than Heisenberg allows? - Uncertainty in the presence of a quantum memory

Quantum cryptography is the safest way to encrypt data. It utilises the fact that transmitted information can only be measured with a strictly limited degree of precision. Scientists at Ludwig-Maximilians-University (LMU) in Munich and ETH Zürich have now discovered how the use of a quantum memory affects this uncertainty.
A quantum particle is hard to grasp, because one cannot determine all its properties precisely at the same time. Measurements of certain parameter pairs such as position and momentum remain inaccurate to a degree given by Heisenberg's Uncertainty Principle. This is important for the security of quantum cryptography, where information is transmitted in the form of quantum states such as the polarisation of particles of light.
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Quantum computer hits hydrogen bullseye

A basic quantum computer has successfully tackled one of the most challenging tasks facing chemists today - calculating molecular energy from basic scientific principles.
Although knowing a molecule's energy can help predict reaction rates, the computer power needed and complexity of working it out from first principles forces chemists to use approximations, which may be inaccurate. Andrew White of the University of Queensland, Australia, explains that a 2005 study calculated full models for hydrogen and helium, but couldn't go any further.

'They said that for the foreseeable future lithium looks impossible. If you took a molecule with 100 electrons, you couldn't even solve that using every computer in the world at once.'

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"One of the most important problems for many theoretical chemists is how to execute exact simulations of chemical systems. This is the first time that a quantum computer has been built to provide these precise calculations" - Alán Aspuru-Guzik, assistant professor of chemistry and chemical biology at Harvard.

In an important first for a promising new technology, scientists have used a quantum computer to calculate the precise energy of molecular hydrogen. This groundbreaking approach to molecular simulations could have profound implications, not just for quantum chemistry, but also for a range of fields from cryptography to materials science.

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First-ever calculation performed on optical quantum computer chip
A primitive quantum computer that uses single particles of light (photons) whizzing through a silicon chip has performed its first mathematical calculation. This is the first time a calculation has been performed on a photonic chip and it is major step forward in the quest to realise a super-powerful quantum computer.

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