One step closer to quantum computers

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Summary: Rice University physicists have created a tiny “electron superhighway” that could one day be useful for building a quantum computer.

The promise of quantum computing is largely predicated on whether or not physicists can keep quantum bits, or “qubits,” from slipping out of their two-state existence due to quantum fluctuations. This fundamental limitation has spawned research into different approaches to creating qubits.

Credit: Jeff Fitlow/Rice University

The latest comes from Rice University, where physicists have created a device called a “quantum spin Hall topological insulator” which acts as a tiny electron superhighway designed for increased fault-tolerance.

The researchers claim that the device is one of the building blocks needed to create quantum particles that store and manipulate data.

A quantum computer uses quantum particles in place of the digital transistors found in today’s microchips. These particles — atoms, electrons, or qubits — can be both ones and zeros at the same time, thanks to the quirks of quantum mechanics. This gives quantum computers a huge edge in performing intense computing tasks like code-breaking, climate modeling and biomedical simulation.

“In principle, we don’t need many qubits to create a powerful computer. In terms of information density, a silicon microprocessor with 1 billion transistors would be roughly equal to a quantum processor with 30 qubits,” said Rui-Rui Du, a Rice physicist behind the research.

Du and colleague Ivan Knez describe their approach to topological quantum computing in a recent paper published in Physical Review Letters.

According to Rice, “topological designs are expected to be more fault-tolerant than other types of quantum computers because each qubit in a topological quantum computer will be made from a pair of quantum particles that have a virtually immutable shared identity.”

But there is a catch to the topological approach. Physicists have yet to create or observe one of these stable pairs of particles, which are called “Majorana fermions” (pronounced MAH-yor-ah-na FUR-mee-ons).

Majorana fermions were first proposed in 1937 and the search for the elusive particles is becoming an obsession in the condensed-matter community. Physicists believe the particles can be made by marrying a two-dimensional topological insulator — like the one created by Du and Knez — to a superconductor.

According to Knez, if a small square of a topological insulator is attached to a superconductor then the elusive Majorana fermions are expected to appear precisely where the materials meet. If this proves true, the devices could potentially be used to generate qubits for quantum computing.

Knez spent more than a year refining the techniques to create Rice’s topological insulator. The device is made from a commercial-grade semiconductor that’s commonly used in making night-vision goggles.

Du said it is the first 2-D topological insulator made from a material that physicists already know how to attach to a superconductor.

“We are well-positioned for the next step,” Du said. “Meanwhile, only experiments can tell whether we can find Majorana fermions and whether they are good candidates for creating stable qubits.”

Related:

Breakthrough removes major hurdle for quantum computing
Scientists create a single-electron transistor: A big step for quantum computing?

Christopher Jablonski is a freelance technology writer.

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$1,000 house a step closer for world's poor

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Summary: MIT architects have produced the first prototype “Pinwheel House” in an effort to see if low-cost homes can be constructed for $1,000, total.

The brainpower at MIT has been harnessed to help improve housing conditions for the billions of people living in poor rural conditions on less than $1 per day.

The first prototype from the Institute’s “1K House” project–an effort launched in 2009 to see if low-cost homes can be constructed for $1,000–has been constructed in Mianyang, in Sichuan Province, China, an area ravaged by the 2008 earthquake.

Pinwheel House interior. Credit: Ying Chee Chui

Pinwheel House is modular dwelling consisting of two natural materials, earth block and bamboo, that can be easily assembled via interlocking rectangular room units that surround a central courtyard space.

It was designed by Ying Chee Chui, a graduate of MIT’s Department of Architecture and currently an architectural practitioner in New York City.

“The module can be duplicated and rotated, and then it becomes a house,” Chui says. “The construction is easy enough, because if you know how to build a single module, you can build the whole house.”

Drawing inspiration from One Laptop Per Child, the idea for a $1,000 homes was first conceived as a design challenge by Tony Ciochetti who chairs MIT’s Center for Real Estate.

Chui’s house is one of 13 plans that emerged from the first 1K House design studio. It features hollow brick walls with steel bars for reinforcement, wooden box beams, and is intended to withstand a magnitude 8.0 earthquake. The first prototype measured 800 square feet and turned out to be more costly, at $5,925, but still very inexpensive in relative terms.

A 500 square feet version of the house could be built for about $4,000, according to Chui, and still lower if a large number of the homes were built at once. Nonetheless, Yung Ho Chang, a professor of architectural design at MIT who helped oversee the 2009 1K House design studio, thinks the prototype has fulfilled the promise of Chui’s design. “The house Chee built has good ventilation and good light,” Chang says.

But plenty of hurdles remain before any home can be manufactured for $1,000 or less. “If it were easy, somebody would have done it,” Ciochetti says.

The house is made of modules 13.8 sqm. The assembly method is the same for each unit, thus, if you know how to build one module, you know how to build them all. Credit: MIT

At any rate, the project’s success has spawned a related effort for home designs intended for Japan, A new MIT design studio is working on a home that would cost $10,000 to build. It would provide housing for victims of natural disasters, such as the earthquake and tsunami that struck northern Japan last March.

Ultimately, convening further studios in the vein of the 1K House project will allow more designs to move from the drawing board and onto solid ground, according to Chang. “The inexpensive laptop got to be more than an idea, it became available for children. I hope one day we’ll be in the same position.”

Christopher Jablonski is a freelance technology writer.

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