LA13023AR
Curiosity Doesn't Kill the Cat
In Schroedinger's famous thought experiment, a cat might exist in a nebulous quantum state, in which it is neither alive nor dead. But upon an observer looking to *see* if the cat is alive or not, it reverts immediately to one of the two possibilities, destroying the quantum weirdness. Physicists at the University of Massachusetts at Boston have shown how such a nebulous quantum state could be viewed, and even controlled in real-time, without forcing the "cat" into being alive or dead. The experimenter's curiosity need not kill the cat. In this case, the "cat" is actually a nano-scopic mechanical "guitar string", fabricated on a micro-chip. The string is placed in a nebulous state in which the string is at two different positions at the same time. By using a superconducting circuit to monitor the resonator, an experimenter could control the motion of the string, while it continues to exist at both locations.
Wednesday, March 23, 2011
LU12546
How does water play around biomolecules?
How important is water for biological tissues? For the bottom-up understanding of the importance from molecular level, it is essential to clarify the hydration states of biomolecules precisely, i.e., we need to know how many water molecules are perturbed by the biomolecules. Such the hydration effect has been usually estimated from the extent of slowing down of water dynamics at the surface of the biomolecule. Although water dynamics should be observed in sub-picosecond time scale to detect the slight effect of hydration in detail, past studies could not reach such the observation in the ultrafast time scale. In this paper, we clarify the precise hydration state of a model biomembrane (phospholipid bilayer) from observation of ultrafast dynamics of water molecules by using terahertz spectroscopy. In combination with the structural information of the stacking model biomembranes by X-ray scattering, this advanced technique reveals that the volume of perturbed hydration water is five times as much as previously thought, and it reaches up to 1 nm far from the membrane surface. This indicates most of water between the membranes does not behave as normal water.
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EYJ1044
Travelling salesmen should follow their noses
Research published in Physical Review E shows how cells of the immune system can solve the 'travelling salesman problem' and so minimise the time taken to eradicate multiple sites of infection. This becomes crucial when airborne bacteria get distributed throughout the lungs. The 'Travelling Salesman Problem' is easily stated but notoriously different to solve. The problem is to find the shortest possible route between many cities (infection sites), visiting each city just once. Even the best computers struggle with the problem. There are, after all, more than 2 million, million, million, million ways to travel between just 20 cities. The new research shows that good solutions will be found if the salesmen, like immune cells, were guided by their sense of smell, moving up gradients in the combined smell produced by the cities. This provides new insights into the workings of the immune system, and into the movement patterns of the diverse range of organisms that sniff out their prey.
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LV12113
Quantum Fuzziness Reduced
The weird laws of quantum mechanics predict a fundamental fuzziness in where a quantum arrow points in space, akin to having a compass whose needle is hard to read no matter how hard you squint. The fuzziness of these arrows, called spins, can be reduced by using lots of identical arrows and averaging where they each point. This approach is called the standard quantum limit (SQL). To go beyond the standard quantum limit, one can combine the compasses into a single super-compass in which the fuzziness of each compass partially cancels. The glue that holds the compasses together is called quantum entanglement. Researchers now have used quantum measurements to create entanglement that glued together the equivalent of a million pairs of rubidium atoms. To do this, the researchers placed the atoms between two mirrors and watched how light was modified as it bounced between the mirrors. The measurement process caused the atoms to undergo a quantum "collapse" into an entangled state with reduced fuzziness when the researchers analyzed their measurements. In the future, this approach may help improve the global positioning system or monitor changes in the physical laws of the universe.
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LZ12781
Superconducting Vacuum
The main result of this paper is that the vacuum, in the presence of a very strong magnetic field, becomes a superconductor. Moreover, the properties of the superconducting state of the vacuum are drastically different from those of a "textbook" superconductor. All textbooks state that one of the key properties of a superconductor is that it expels a weak external magnetic field. The textbooks also stress that a sufficiently strong external magnetic field will destroy the superconductivity property. Finally, it is taken for granted that a superconductor is a material object; i.e. it is composed of ordinary matter. In our paper we demonstrate that the vacuum becomes a superconductor if it is exposed to an enormous magnetic field. We show that the vacuum, which is by definition the absence of matter, becomes a superconductor due to magnetic field-induced condensation of certain quantum fluctuations. The superconducting state is a high temperature superconductor which is able to survive high temperatures of the order of billions degrees Kelvin (a typical scale of strong interactions). Magnetic fields of the required magnitude may be generated for short times during the evolution of the early Universe, and in heavy-ion collisions at the Large Hadron Collider facility at CERN.
How does water play around biomolecules?
How important is water for biological tissues? For the bottom-up understanding of the importance from molecular level, it is essential to clarify the hydration states of biomolecules precisely, i.e., we need to know how many water molecules are perturbed by the biomolecules. Such the hydration effect has been usually estimated from the extent of slowing down of water dynamics at the surface of the biomolecule. Although water dynamics should be observed in sub-picosecond time scale to detect the slight effect of hydration in detail, past studies could not reach such the observation in the ultrafast time scale. In this paper, we clarify the precise hydration state of a model biomembrane (phospholipid bilayer) from observation of ultrafast dynamics of water molecules by using terahertz spectroscopy. In combination with the structural information of the stacking model biomembranes by X-ray scattering, this advanced technique reveals that the volume of perturbed hydration water is five times as much as previously thought, and it reaches up to 1 nm far from the membrane surface. This indicates most of water between the membranes does not behave as normal water.
***
EYJ1044
Travelling salesmen should follow their noses
Research published in Physical Review E shows how cells of the immune system can solve the 'travelling salesman problem' and so minimise the time taken to eradicate multiple sites of infection. This becomes crucial when airborne bacteria get distributed throughout the lungs. The 'Travelling Salesman Problem' is easily stated but notoriously different to solve. The problem is to find the shortest possible route between many cities (infection sites), visiting each city just once. Even the best computers struggle with the problem. There are, after all, more than 2 million, million, million, million ways to travel between just 20 cities. The new research shows that good solutions will be found if the salesmen, like immune cells, were guided by their sense of smell, moving up gradients in the combined smell produced by the cities. This provides new insights into the workings of the immune system, and into the movement patterns of the diverse range of organisms that sniff out their prey.
***
LV12113
Quantum Fuzziness Reduced
The weird laws of quantum mechanics predict a fundamental fuzziness in where a quantum arrow points in space, akin to having a compass whose needle is hard to read no matter how hard you squint. The fuzziness of these arrows, called spins, can be reduced by using lots of identical arrows and averaging where they each point. This approach is called the standard quantum limit (SQL). To go beyond the standard quantum limit, one can combine the compasses into a single super-compass in which the fuzziness of each compass partially cancels. The glue that holds the compasses together is called quantum entanglement. Researchers now have used quantum measurements to create entanglement that glued together the equivalent of a million pairs of rubidium atoms. To do this, the researchers placed the atoms between two mirrors and watched how light was modified as it bounced between the mirrors. The measurement process caused the atoms to undergo a quantum "collapse" into an entangled state with reduced fuzziness when the researchers analyzed their measurements. In the future, this approach may help improve the global positioning system or monitor changes in the physical laws of the universe.
***
LZ12781
Superconducting Vacuum
The main result of this paper is that the vacuum, in the presence of a very strong magnetic field, becomes a superconductor. Moreover, the properties of the superconducting state of the vacuum are drastically different from those of a "textbook" superconductor. All textbooks state that one of the key properties of a superconductor is that it expels a weak external magnetic field. The textbooks also stress that a sufficiently strong external magnetic field will destroy the superconductivity property. Finally, it is taken for granted that a superconductor is a material object; i.e. it is composed of ordinary matter. In our paper we demonstrate that the vacuum becomes a superconductor if it is exposed to an enormous magnetic field. We show that the vacuum, which is by definition the absence of matter, becomes a superconductor due to magnetic field-induced condensation of certain quantum fluctuations. The superconducting state is a high temperature superconductor which is able to survive high temperatures of the order of billions degrees Kelvin (a typical scale of strong interactions). Magnetic fields of the required magnitude may be generated for short times during the evolution of the early Universe, and in heavy-ion collisions at the Large Hadron Collider facility at CERN.
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