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Quantum ‘alphabet’ easier to read with laser boost
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Miriam Reik/Millenium
IS THE brain a clock that can reveal someone’s age? There is no doubt that children of the same age often differ in their maturity and mental ability, says Timothy Brown at the University of California in San Diego. But it is not clear how much of that difference is biological rather than psychological. To find out, Brown and his colleagues used structural magnetic resonance imaging (MRI) to study the brains of 885 children and young adults between the ages of 3 and 20. The images could detect features such as the size of each brain region and the level of connectivity between neurons. They plugged all of these features into software that formed a picture of what the average brain looks like at each year of development. They found that their system could correctly predict a person’s age with 92 per cent accuracy within the 3 to 20 age range – beyond what is possible with other techniques (Current Biology, doi.org/h6n). Brown says the technique could be used to determine whether a child’s brain is developing normally for his or her age. Paediatric neurologist Nico Dosenbach at Washington University in St Louis, Missouri, who was not involved in the study, compares it to the children’s growth chart used by clinicians.
‘Eye bath’ to thank for birds’ quantum vision MOVE over, Schrödinger’s cat – birds may be the true quantum animals. A bath of cells in the back of a bird’s eye could prolong a delicate quantum state that helps to explain how some birds navigate using Earth’s magnetic field. It is thought that light reacts with receptors in the birds’ eyes to produce two molecules with unpaired electrons, which are linked by a special state called entanglement. If the shared orientation of the electrons is affected by the magnetic field,
the pair causes chemical changes that the bird can sense. In 2009, researchers at the University of Oxford calculated that such entanglement must last for at least 100 microseconds for the internal compass to work. But how the sensitive state of entanglement could survive that long in the eye was a mystery. Calculations by Zachary Walters of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, now show that interactions with cells in the bird’s eye allow the electron pairs to stay
entangled for longer through a dampening effect (arxiv.org/ abs/1208.2558v1). Rather like the way an old car might continue bouncing after going over a bump, the signal from the electron pair dies away slowly in the cellular bath. Predicting exactly how long entanglement is sustained won’t be possible until the mechanism is better understood, says Walters. Erik Gauger, part of the Oxford team, says this could account for the 100 microseconds, “but it is probably too early to say for sure”. M. Bellini/National Inst. of Optics
Age revealed by brain’s anatomy
That’s music to locked-in ears FAMILIAR music could help people with locked-in syndrome. Listening to a favourite song might boost the brain’s ability to respond to other stimuli in people with disorders of consciousness. Fabien Perrin at the University of Lyon, France, and colleagues recorded brain activity in four patients – two in a coma, one in a minimally conscious state, and one in a vegetative state – while they were read a list of people’s names, including the subject’s own name. The list was preceded either by the subject’s favourite music or by “musical noise”. In all four people, playing the music rather than musical noise enhanced the quality of the brain response to their own name – although music did not similarly enhance the brain response of healthy volunteers. The work was presented at the Association for the Scientific Study of Consciousness meeting in Brighton, UK, last month. “Listening to preferred music activates memory of our past,” says Perrin, “so it could make it easier for the subsequent perception of another autobiographical stimulus, such as your name.”
Photon ‘alphabet’ gets easier to read SECRET agents take note: a new technique for extending the “alphabet” of individual photon shapes could improve encrypted communications. A photon’s shape is based on the probability of detecting it at a particular place and time, depending on its amplitude and frequency. Quantum communication schemes can reliably send and receive photons that have been sculpted into just two variants, determined by the polarisation of the photon – either horizontal or vertical. Although it’s possible to create
photons in almost any shape, more complex configurations become distorted when travelling through an optical fibre, making them harder to understand at the receiving end. Now Marco Bellini and colleagues at the National Institute of Optics in Florence, Italy, have cut through the fuzz. The team mixed photons with shaped laser pulses that either strengthen or cancel out the signal (Physical Review Letters, DOI: 10.1103/PhysRevLett.109.053602). The more the shapes match, the better the odds of detecting the photons at the receiving end.
25 August 2012 | NewScientist | 17
Miriam Reik/Millenium
IS THE brain a clock that can reveal someone’s age? There is no doubt that children of the same age often differ in their maturity and mental ability, says Timothy Brown at the University of California in San Diego. But it is not clear how much of that difference is biological rather than psychological. To find out, Brown and his colleagues used structural magnetic resonance imaging (MRI) to study the brains of 885 children and young adults between the ages of 3 and 20. The images could detect features such as the size of each brain region and the level of connectivity between neurons. They plugged all of these features into software that formed a picture of what the average brain looks like at each year of development. They found that their system could correctly predict a person’s age with 92 per cent accuracy within the 3 to 20 age range – beyond what is possible with other techniques (Current Biology, doi.org/h6n). Brown says the technique could be used to determine whether a child’s brain is developing normally for his or her age. Paediatric neurologist Nico Dosenbach at Washington University in St Louis, Missouri, who was not involved in the study, compares it to the children’s growth chart used by clinicians.
‘Eye bath’ to thank for birds’ quantum vision MOVE over, Schrödinger’s cat – birds may be the true quantum animals. A bath of cells in the back of a bird’s eye could prolong a delicate quantum state that helps to explain how some birds navigate using Earth’s magnetic field. It is thought that light reacts with receptors in the birds’ eyes to produce two molecules with unpaired electrons, which are linked by a special state called entanglement. If the shared orientation of the electrons is affected by the magnetic field,
the pair causes chemical changes that the bird can sense. In 2009, researchers at the University of Oxford calculated that such entanglement must last for at least 100 microseconds for the internal compass to work. But how the sensitive state of entanglement could survive that long in the eye was a mystery. Calculations by Zachary Walters of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, now show that interactions with cells in the bird’s eye allow the electron pairs to stay
entangled for longer through a dampening effect (arxiv.org/ abs/1208.2558v1). Rather like the way an old car might continue bouncing after going over a bump, the signal from the electron pair dies away slowly in the cellular bath. Predicting exactly how long entanglement is sustained won’t be possible until the mechanism is better understood, says Walters. Erik Gauger, part of the Oxford team, says this could account for the 100 microseconds, “but it is probably too early to say for sure”. M. Bellini/National Inst. of Optics
Age revealed by brain’s anatomy
That’s music to locked-in ears FAMILIAR music could help people with locked-in syndrome. Listening to a favourite song might boost the brain’s ability to respond to other stimuli in people with disorders of consciousness. Fabien Perrin at the University of Lyon, France, and colleagues recorded brain activity in four patients – two in a coma, one in a minimally conscious state, and one in a vegetative state – while they were read a list of people’s names, including the subject’s own name. The list was preceded either by the subject’s favourite music or by “musical noise”. In all four people, playing the music rather than musical noise enhanced the quality of the brain response to their own name – although music did not similarly enhance the brain response of healthy volunteers. The work was presented at the Association for the Scientific Study of Consciousness meeting in Brighton, UK, last month. “Listening to preferred music activates memory of our past,” says Perrin, “so it could make it easier for the subsequent perception of another autobiographical stimulus, such as your name.”
Photon ‘alphabet’ gets easier to read SECRET agents take note: a new technique for extending the “alphabet” of individual photon shapes could improve encrypted communications. A photon’s shape is based on the probability of detecting it at a particular place and time, depending on its amplitude and frequency. Quantum communication schemes can reliably send and receive photons that have been sculpted into just two variants, determined by the polarisation of the photon – either horizontal or vertical. Although it’s possible to create
photons in almost any shape, more complex configurations become distorted when travelling through an optical fibre, making them harder to understand at the receiving end. Now Marco Bellini and colleagues at the National Institute of Optics in Florence, Italy, have cut through the fuzz. The team mixed photons with shaped laser pulses that either strengthen or cancel out the signal (Physical Review Letters, DOI: 10.1103/PhysRevLett.109.053602). The more the shapes match, the better the odds of detecting the photons at the receiving end.
25 August 2012 | NewScientist | 17