This week in science is a review of the most interesting scientific news of the past week.
Jupiter is the oldest planet in the Solar system
Scientists from the Lawrence Livermore National Laboratory and the University of Münsterin, Germany, have found evidence that Jupiter is the oldest planet in the solar system. Because no samples from the planet itself are currently available, they have analyzed tungsten and molybdenum isotopes from iron meteorites known to be made up from two distinct nebular reservoirs that coexisted when the solar system begun but were separated by the time of Jupiter's formation. As stated by Thomas Kruijer, lead author of the paper:
Our measurements show that the growth of Jupiter can be dated using the distinct genetic heritage and formation times of meteorites.
Jupiter's solid core of about 20 Earth masses formed within the first one million years after the beginning of the solar system, what was inferred from isotope signatures of meteorites. The solid core then created a barrier against the transport of material across the solar accretion disk of gas and dust, what first separated those two nebular reservoirs. It took another two to four million years for Jupiter to achieve 50 Earth masses and the barrier may also explain why no super-Earth exists in the solar system as well.
Success in a groundbreaking experiment on quantum entanglement-based communication
Quantum entanglement is a weird phenomena in which photons are linked once created and are aware of each other's experiences even when physically separated by a great distance. Because of such property and the possibility of being used to create quantum-based security channels, this phenomena is being widely studied as a potential alternative for current communication technologies.
A team of scientists from the Hefei University in China have successfully generated, for the first time, pairs of entangled photons in space. They have used a laser on a satellite orbiting 300 miles above the planet, which were transmitted to two ground-based stations 750 miles (or 1,200 kilometers) apart without breaking the entanglement, what accounts for ten times the previous record.
In order to increase the distance, the team has placed both receiver stations in the mountains of Tibet. Because the stations were both at a high altitude, the entangled photons trajectories had less air to traverse and, therefore, less likelihood of interacting with other particles and breaking the entanglement.
American and European teams are also considering to send quantum-based equipment to the International Space Station, and one interesting test being targeted is the study of gravitational effects on quantum entanglement. Such a test is of high importance because the link between Quantum Mechanics and General Relativity, which deals with gravity, is one of the main open questions of Physics.
Quantum dot transistors that operate like neurons
A transistor capable of seeing light, counting, and storing information in its own structure was invented by a team of researchers from the Federal University of São Carlos (UFSCar) in Brazil, Würzburg University in Germany, and the University of South Carolina in the United States. Because the device doesn't require a memory unit, it operates in a way that resembles a neuron. According to Victor Lopez Richard, from UFSCar:
Transistors based on quantum dots can perform complex operations directly in memory. This can lead to the development of new kinds of device and computer circuit in which memory units are combined with logical processing units, economizing space, time, and power consumption.
In order to develop the memory functionality, the researchers have used the dynamics of charging and discharging the quantum dots, that could be modulated either by applying a voltage to the transistor's gates or by the absorption of light by the quantum dots.
Unfortunately, the new transistor can currently work only at extremely low temperatures of approximately four Kelvin, which is the temperature of liquid helium. The team now aims at enabling the device to operate at higher temperatures, including room temperature.