Ultrasensitive gas sensors based on the infusion of boron atoms into graphene—a tightly bound matrix of carbon atoms—may soon be possible, according to an international team of researchers from six countries.
In August I went to Stephen Hawking’s public lecture in the fully packed Stockholm Opera. Hawking was wheeled onto the stage, placed in the spotlight, and delivered an entertaining presentation about black holes. The silence of the audience was interrupted only by laughter to Hawking’s well-placed jokes. It was a flawless performance with standing ovations.
In his lecture, Hawking expressed hope that he will win the Nobelprize for the discovery that black holes emit radiation. Now called “Hawking radiation,” this effect should have been detected at the LHC had black holes been produced there. But time has come, I think, for Hawking to update his slides. The ship to the promised land of micro black holes has long left the harbor, and it sunk – the LHC hasn’t seen black holes, has not, in fact, seen anything besides the Higgs.
But you don’t need black holes to see Hawking radiation. The radiation is a consequence of applying quantum field theory in a space- and time-dependent background, and you can use some other background to see the same effect. This can be done, for example, by measuring the propagation of quantum excitations in Bose-Einstein condensates. These condensates are clouds of about a billion or so ultra-cold atoms that form a fluid with basically zero viscosity. It’s as clean a system as it gets to see this effect. Handling and measuring the condensate is a big experimental challenge, but what wouldn’t you do to create a black hole in the lab?
Australian scientists have designed a 3D silicon chip architecture based on single atom quantum bits, which is compatible with atomic-scale fabrication techniques — providing a blueprint to build a large-scale quantum computer.
China has announced that it will begin construction of the world’s largest particle collider in 2020. According to officials, the subterranean facility will be at least twice the size of the Large Hadron Collider (LHC) in Switzerland, and will endeavour to find out more about the mysterious Higgs boson.
The final concept design won’t be completed until the end of next year, so we don’t have many details to go on, but the collider is expected to smash protons and electrons together at seven times the energy levels of the LHC, generating millions of Higgs bosons in the process. Best of all, the facility will reportedly be available to the entire global scientific community.
“This is a machine for the world and by the world: not a Chinese one,” Wang Yifang, director of the Institute of High Energy Physics at the China Academy of Sciences, told the government-controlled publication, China Daily, this week.
Researchers are getting ready to turn on the world’s biggest ‘Stellarator’ fusion reactor. Called Wendelstein 7-X (W7-X), the reactor can uninterruptedly contain super-hot plasma for more than 30 minutes at a time. Scientists claim the rare design, which is contained in a giant lab in Greifswald, Germany, can finally help make fusion power a reality. Comprising super-hot plasma for long durations has been the Holy Grail for nuclear reactor designs, and can help researchers to deliver an inexhaustible source of power. Fusion reactors, for instance the W7-X, work by using two isotopes of hydrogen atoms — deuterium and tritium — and inserting that gas into a restraint vessel. Researcher then add energy that eliminates the electrons from their host atoms, creating what is described as an ion plasma, which discharges enormous amounts of energy.
A Hall thruster is powering many of the satellites moving around Earth right now. It needs 100 million (yes, you read that right, 100 million) times less fuel than chemical thrusters. But it was never remotely sturdy enough to get anything to Mars—until now.
Typical chemical thrusters are pretty simple. Fuel combusts, gases shoot one way, and a rocket shoots the other way.
Ion thrusters are a little different. They contain charged electrodes, an anode and a cathode, and allow positively charged ions to shoot from the anode to the cathode. Thanks to momentum, the ions will “overshoot” the cathode. Under regular circumstances they’d be sucked back, but once they’ve cleared the cathode, they’re hit by a beam of electrons, neutralizing them and allowing them to go on their way without interference from the charged cathode. So the neutralized atoms shoot one way, and the rocket shoots another.
One of the oddest predictions of quantum theory – that a system can’t change while you’re watching it – has been confirmed in an experiment by Cornell physicists. Their work opens the door to a fundamentally new method to control and manipulate the quantum states of atoms and could lead to new kinds of sensors.
The experiments were performed in the Utracold Lab of Mukund Vengalattore, assistant professor of physics, who has established Cornell’s first program to study the physics of materials cooled to temperatures as low as .000000001 degree above absolute zero. The work is described in the Oct. 2 issue of the journal Physical Review Letters
Graduate students Yogesh Patil and Srivatsan K. Chakram created and cooled a gas of about a billion Rubidium atoms inside a vacuum chamber and suspended the mass between laser beams. In that state the atoms arrange in an orderly lattice just as they would in a crystalline solid.,But at such low temperatures, the atoms can “tunnel” from place to place in the lattice. The famous Heisenberg uncertainty principle says that the position and velocity of a particle interact. Temperature is a measure of a particle’s motion. Under extreme cold velocity is almost zero, so there is a lot of flexibility in position; when you observe them, atoms are as likely to be in one place in the lattice as another.
One of the oddest predictions of quantum theory — that a system can’t change while you’re watching it — has been confirmed in an experiment by physicists.
A low-cost, high-speed method for printing graphene inks using a conventional roll-to-roll printing process, like that used to print newspapers and crisp packets, could open up a wide range of practical applications, including inexpensive printed electronics, intelligent packaging and disposable sensors.
Developed by researchers at the University of Cambridge in collaboration with Cambridge-based technology company Novalia, the method allows graphene and other electrically conducting materials to be added to conventional water-based inks and printed using typical commercial equipment, the first time that graphene has been used for printing on a large-scale commercial printing press at high speed.
Graphene is a two-dimensional sheet of carbon atoms, just one atom thick. Its flexibility, optical transparency and electrical conductivity make it suitable for a wide range of applications, including printed electronics. Although numerous laboratory prototypes have been demonstrated around the world, widespread commercial use of graphene is yet to be realised.
Australian scientists created a computer simulation in which quantum particles can move back in time. This might confirm the possibility of time travel on a quantum level, suggested in 1991. At the same time, the study revealed a number of effects which are considered impossible according to the standard quantum mechanics.
Using photons, physicists from the University of Queensland in Australia simulated time-traveling quantum particles. In particular, they studied the behavior of a single photon traveling back in time through a wormhole in space-time and interacting with itself. This time-traveling loop is called a closed timelike curve, i.e. a path followed by a particle which returns to its initial space-time point.
The physicists studied two possible scenarios for a time-traveling photon. In the first, the particle passes through a wormhole, moving back in time, and interacts with its older self. In the second scenario, the photon passes through normal space-time and interacts with another photon which is stuck in a closed timelike curve.
