Spin doctors make something from nothing
26th July 2006
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| UNSW quantum electronic devices group |
Electronic devices are always shrinking in size but it’s hard to imagine anything beating what researchers at the University of New South Wales have created: a tiny wire that doesn’t even use electrons to carry a current.
Known as a hole quantum wire, it exploits the gaps – or holes - between electrons: unlike in a conventional electrical wire, the current flows in the absence of electrons.
The holes can be thought of as real quantum particles that have an electrical charge and a spin. They exhibit remarkable quantum properties and could lead to a new world of super-fast, low-powered transistors and powerful quantum computers.
Associate Professor Alex Hamilton and Dr Adam Micolich, who lead the UNSW Quantum Electronic Devices group say the discovery that the holes can carry an electrical current puts the team at the front of its field in the quantum electronics revolution.
"Research groups around the world have been trying to make these devices for more than a decade and we're the first to do so successfully," Professor Hamilton says. "We really do have a big lead now."
Quantum wires are microscopically small, in this case about 100 times narrower than a human hair. Manufacturers are keenly interested in them because they hold the potential for new high-speed electronics applications, known as spintronics, where semiconductor devices have both electric and magnetic properties.
"The idea that a hole can have such dynamic properties is a hard concept to grasp," says Hamilton. "It's a bit like when you tilt a builder's spirit level: you can either think of the liquid sinking downwards, or the bubble - an absence of liquid - rising upwards. Semiconductors that use holes, rather than electrons, would be good for spintronics and quantum information technologies that use spin to store and process data.
“What we’ve done is to make highly stable hole quantum wires, where the holes can travel without hitting anything else. As the holes pass along the wire, they line up like soldiers marching in single file and our experiments show that their magnetic dipoles (their little bar magnets) all want to point along the wire. Electrons don't do this.
"This means that we can manipulate the spin properties of the holes by forcing them into these narrow quantum wires, which is one of the pre-conditions for making spin-based transistors."
Media contacts: Associate Professor Alex Hamilton: + 61 425 281 636 or UNSW Media Unit, Dan Gaffney: +61 411 156 015
For a conceptual Flash animation see the website
Known as a hole quantum wire, it exploits the gaps – or holes - between electrons: unlike in a conventional electrical wire, the current flows in the absence of electrons.
The holes can be thought of as real quantum particles that have an electrical charge and a spin. They exhibit remarkable quantum properties and could lead to a new world of super-fast, low-powered transistors and powerful quantum computers.
Associate Professor Alex Hamilton and Dr Adam Micolich, who lead the UNSW Quantum Electronic Devices group say the discovery that the holes can carry an electrical current puts the team at the front of its field in the quantum electronics revolution.
"Research groups around the world have been trying to make these devices for more than a decade and we're the first to do so successfully," Professor Hamilton says. "We really do have a big lead now."
Quantum wires are microscopically small, in this case about 100 times narrower than a human hair. Manufacturers are keenly interested in them because they hold the potential for new high-speed electronics applications, known as spintronics, where semiconductor devices have both electric and magnetic properties.
"The idea that a hole can have such dynamic properties is a hard concept to grasp," says Hamilton. "It's a bit like when you tilt a builder's spirit level: you can either think of the liquid sinking downwards, or the bubble - an absence of liquid - rising upwards. Semiconductors that use holes, rather than electrons, would be good for spintronics and quantum information technologies that use spin to store and process data.
“What we’ve done is to make highly stable hole quantum wires, where the holes can travel without hitting anything else. As the holes pass along the wire, they line up like soldiers marching in single file and our experiments show that their magnetic dipoles (their little bar magnets) all want to point along the wire. Electrons don't do this.
"This means that we can manipulate the spin properties of the holes by forcing them into these narrow quantum wires, which is one of the pre-conditions for making spin-based transistors."
Media contacts: Associate Professor Alex Hamilton: + 61 425 281 636 or UNSW Media Unit, Dan Gaffney: +61 411 156 015
For a conceptual Flash animation see the website
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